Hum/111 Week 8 Assignment Appendix Digestive System

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Table of Contents

  • THE EMBRYONIC PERIOD (THE FIRST 8 WEEKS)
  • THE FETAL PERIOD (8 WEEKS THROUGH BIRTH)
    • Chapter 37 – 9 Weeks: Swallows, Sighs, and Stretches
    • Chapter 38 – 10 Weeks: Rolls Eyes and Yawns, Fingernails & Fingerprints
    • Chapter 39 – 11 Weeks: Absorbs Glucose and Water
    • Chapter 40 – 3 to 4 Months (12 to 16 Weeks): Taste Buds, Jaw Motion, Rooting Reflex, Quickening
    • Chapter 41 – 4 to 5 Months (16 to 20 Weeks): Stress Response, Vernix Caseosa, Circadian Rhythms
    • Chapter 42 – 5 to 6 Months (20 to 24 Weeks): Responds to Sound; Hair and Skin; Age of Viability
    • Chapter 43 – 6 to 7 Months (24 to 28 Weeks): Blink-Startle; Pupils Respond to Light; Smell and Taste
    • Chapter 44 – 7 to 8 Months (28 to 32 Weeks): Sound Discrimination, Behavioral States
    • Chapter 45 – 8 to 9 Months (32 to 36 Weeks): Alveoli Formation, Firm Grasp, Taste Preferences
    • Chapter 46 – 9 Months to Birth (36 Weeks through Birth)
    •  
  • APPENDIX A − CALCULATIONS
  • APPENDIX B − RELATING EMBRYONIC AGE & STAGE
  • Bibliography
  • Full Names of Journals Cited
  • Program Index


All embryonic and fetal ages in this program refer to the time since fertilization.
Ages from 4 through 8 weeks are estimated to ±3 days.
Ages from 8 through 12 weeks are estimated to ±5 days.
Ages from 12 weeks through birth are generally estimated to ±1 week.
To simplify age calculations, the term “month“ assumes a 4-week period.
Age and stage conventions adopted during the embryonic period are listed in Appendix B.



Chapter 1   Introduction

The dynamic process by which the single-cell human zygote(zī΄gōt)[1] becomes a 100 trillion (1014) cell adult[2] is perhaps the most remarkable phenomenon in all of nature.

Researchers now know that many of the routine functions performed by the adult body become established during pregnancy – often long before birth.[3]

The developmental period before birth is increasingly understood as a time of preparation during which the developing human acquires the many structures, and practices the many skills, needed for survival after birth.

Chapter 1   Introduction

एकपेशीय मानवी बिजांड ज्या गतिमान प्रक्रियेद्वारा100 खरबपेशींचे विकसीत शरीर होते ही कदाचित निसर्गाची सर्वाधिक वैशिष्ट्यपूर्ण प्रक्रिया आहे.

संशोधकांना आता माहित आहे की पूर्ण विकसीत शरीराद्वारा केल्या जाणाया नित्याच्या अनेक क्रियाबहुतेक वेळा जन्माच्या खूप आधी,गर्भावस्थेच्या दरम्यान स्थापित होतात.

जन्मपूर्व विकासाचा कालावधीपूर्वतयारीया काळ मानला जातोज्याचे दरम्यान विकसनशील मनुष्यजन्मानंतरच्या अस्तित्वाकरीताअनेक संस्था प्राप्त करतो आणि आवश्यक कौशल्यांचा सराव करतो.

Chapter 2   Terminology

Pregnancy in humans normally lasts approximately 38 weeks[4] as measured from the time of fertilization,[5] or conception,[6] until birth.

During the first 8 weeks following fertilization, the developing human is called an embryo,[7] which means "growing within."[8] This time, called the embryonic period,[9] is characterized by the formation of most major body systems.[10]

From the completion of 8 weeks until the end of pregnancy, "the developing human is called a fetus," which means "unborn offspring." During this time, called the fetal period, the body grows larger and its systems begin to function.[11]

All embryonic and fetal ages in this program refer to the time since fertilization.[12]

Chapter 2   Terminology

गर्भधानापासून अथवा लैंगीक संबंधा पासून मोजली असता जन्मापर्यन्तमनुष्याची गर्भावस्था ढोबळमानाने ३८ आठवडयाची असते.

गर्भधानानंतरच्या प्रथम ८ आठवडयाचे दरम्यानविकसनशील मानवी शरीरास भ्रुण म्हणतात ज्याचा अर्थ 'आंत वाढणारा' असा होतो.भ्रुण अवस्थेचा काल म्हटला जाणार्याह्या, कालावधीत शरीरातील अधिकतर मुख्य संस्था निर्माण होतात.

८ आठवडयांच्या पूर्तीपासून गर्भावस्थेच्या शेवटापर्यन्तविकसनशील मानवी शरीरास गर्भस्थ शिशु म्हणतात ज्याचा अर्थ न जन्मलेले तान्हुले असा आहे.गर्भावस्थेच्या या कालवधीत,शरीर विकसीत होते आणि त्यातील संस्था काम करण्यास सुरवात करतात.

सर्व गर्भावस्थीय व भ्रुणाच्या अवस्थांचे वर्णन या कार्यक्रमातगर्भधानानंतरच्या कालावधीच्या संदर्भात केले आहे.

 

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[1]Gasser, 1975, 1.
[2]Guyton and Hall, 2000, 2; Lodish et al., 2000, 12.
[3]Vindla and James, 1995, 598.
[4]Cunningham et al., 2001, 226; O’Rahilly and Müller, 2001, 92.
[5]O’Rahilly and Müller, 1987, 9.
[6]Spraycar, 1995, 377 & 637.
[7]O’Rahilly and Müller, 2001, 87.
[8] Quote from Ayto, 1990, 199.
[9] Human development during the 8-week embryonic period has been divided into a series of 23 stages called Carnegie Stages. These stages are well described in O’Rahilly and Müller, 1987. Because human growth is unique and dependent on multiple factors, different embryos may reach a certain developmental milestone or a certain size at slightly different ages. This internationally-accepted staging system provides a way to describe development independent of age and size. Each of the 23 Carnegie Stages has specific structural features. As we describe various milestones of development, the Carnegie Stage at which they occur will be noted by a designation such as: [Carnegie Stage 2]. See Appendix B for additional information relating embryonic staging and age assignments.
[10]Moore and Persaud, 2003, 3.
[11] Quotes from Moore and Persaud, 2003, 3: “After the embryonic period (eight weeks), the developing human is called a fetus.“ Also see O’Rahilly and Müller, 2001, 87.
[12] This convention, termed “postfertilization age“ by O’Rahilly, has been long preferred by embryologists. [see Mall, 1918, 400; O’Rahilly and Müller, 1999b, 39; O’Rahilly and Müller, 2001, 88 & 91.] Obstetricians and radiologists typically assign age based on the time elapsed since the first day of the last menstrual period prior to fertilization. This is correctly termed “postmenstrual age“ and begins 2 weeks before fertilization occurs. To summarize: postmenstrual age = postfertilization age + 2 weeks. Therefore, postmenstrual age equals approximately 2 weeks at the time of fertilization. The commonly used term “gestational age“ has been used with both age conventions and is best either avoided or carefully defined with each use.

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The Embryonic Period (The First 8 Weeks)

Embryonic Development: The First 4 Weeks

Chapter 3   Fertilization

Biologically speaking, "human development begins at fertilization,"[13] when a woman and a man each combine 23 of their own chromosomes through the union of their reproductive cells.

A woman's reproductive cell is commonly called an "egg" but the correct term is oocyte (ō´ō-sīt).[14]

Likewise, a man's reproductive cell is widely known as a "sperm," but the preferred term is spermatozoon (sper´mă-tō-zō´on).[15]

Following the release of an oocyte from a woman's ovary in a process called ovulation (ov´yū-lā´shŭn),[16] the oocyte and spermatozoon join within one of the uterine tubes,[17] which are often referred to as Fallopian tubes.

The uterine tubes link a woman's ovaries to her uterus or womb.

The resulting single-celled embryo is called a zygote,[18] meaning "yoked or joined together."[19]

The Embryonic Period (The First 8 Weeks)

Embryonic Development: The First 4 Weeks

Chapter 3   Fertilization

जीवशास्त्राच्या दृष्टिकोनातूनमनुष्याचा विकास गर्भधानापासून सुक होतोजेंव्हा एक स्त्री व एक पुरुष पुनरूत्पादक पेशींच्या संयोगातुनआपल्या २३ गुणसुत्रांचे मिलन करतो.

स्त्रीच्या पुनरुत्पादक पेशींन्या सामान्यतः अंडे म्हणतातपरंतु योग्य शब्द जनकाणु आहे.

त्याचप्रमाणे पुरुषाच्या पुनरुत्पादक पेशींनासर्वत्र "विर्य" म्हणतात जातेपरंतु अधिक उचित शब्द शुक्राणु आहे.

स्त्रीच्या अंडकोषातून जनकाणु सोडण्याच्या डिम्बोत्सर्ग नावाच्या प्रक्रीयेनंतरगर्भाशयाच्या फॉलोपिअन टयूब नावाच्या नलिकेतशुक्राणु व जनकाणु एकत्र होतातज्यांना सामान्यतः म्हणतात.

गर्भाशयाच्या नलिका स्त्रीच्या अंडकोषाला तीच्या गर्भाशयाशी जोडतात

निष्पादित एकपेशीय गर्भास बीजांड म्हणतातयाचाअर्थ ''संयुक्त वा एक साथ जोडलेले'' असा होतो.

Chapter 4   DNA, Cell Division, and Early Pregnancy Factor (EPF)

DNA

The zygote's 46 chromosomes[20] represent the unique first edition of a new individual's complete genetic blueprint. This master plan resides in tightly coiled molecules called DNA. They contain the instructions for the development of the entire body.

DNA molecules resemble a twisted ladder known as a double helix.[21] The rungs of the ladder are made up of paired molecules, or bases, called guanine, cytosine, adenine, and thymine.

Guanine pairs only with cytosine, and adenine with thymine.[22] Each human cell contains approximately 3 billion (3×109) base pairs.[23]

The DNA of a single cell contains so much information that if it were represented in printed words, simply listing the first letter of each base would require over 1.5 million (1.5×106) pages of text![24]

If laid end-to-end, the DNA in a single human cell measures 3⅓ feet or 1 meter.[25]

If we could uncoil all of the DNA within an adult's 100 trillion (1014) cells, it would extend over 63 billion (6.3×1010) miles. This distance reaches from the earth to the sun and back 340 times.[26]

Cell Division

Approximately 24 to 30 hours after fertilization, the zygote completes its first cell division.[27] Through the process of mitosis, one cell splits into two, two into four, and so on.[28]

Early Pregnancy Factor (EPF)

As early as 24 to 48 hours after fertilization begins, pregnancy can be confirmed by detecting a hormone called "early pregnancy factor" in the mother's blood.[29]

Chapter 4   DNA, Cell Division, and Early Pregnancy Factor (EPF)

DNA

बीजांडाचे ४६ गुणसुत्र नवजाताच्या पूर्ण अनुवांशिक नकाशाच्या अद्वितीयप्रथम संस्करणाचे प्रतिनिधित्व करतात.ही श्रेष्ठ योजना डि.एन.ए.नावाच्या घट्ट वक्र परमाणुत असते.त्यांच्यात संपूर्ण शरीराच्या विकासाच्या सुचना असतात.

डि.एन.ए. परमाणु पिळदार शिडीप्रमाणे असतात ज्यांना डबल हेलिक्स म्हटले जाते.शिडीचे दांडे संयुक्त परमाणुंनी बनलेले असतातज्यांना गुनाइन सायटोसीन, अडेनीन आणि थायमाइन म्हणतात.

गुनाइन फक्त सायटोसीन बरोबरआणि अडेनीन थायमाइन बरोबर संयुक्तहोते.प्रत्येक मानवीपेशीत ठोबळमानाने अशा ३० अरब मूल जोड्यां असतात.

एका पेशीच्या डि.एन.ए. मधे भरपूर माहिती असतेकेवल प्रत्येक मूल तत्वाचे प्रथम अक्षराची सूची करतजर ती छापील शब्दात लिहिली तरपुस्तकाच्या १५ लाख पानांची गरज पडेल !

जर एका टोकापासून दुसया टोकापर्यन्त मांडली तरएका मानवी पेशीतील डि.एन.ए. ची लांबी ३ १/३ फूट किंवा १ मिटर असते.

जर आपण प्रौढ़ व्यक्तिच्या १०० खरब पेशीतीलसर्व डि.एन.ए. उलगडू शकलो तरते ६३ अरब मैल लांब पसरेल.ही लांबी पृथ्वीपासून सूर्यापर्यन्त आणि परतीच्या एकूण अंतराच्या ३४० पट आहे.

Cell Division

ढोबळ मानाने गर्भधानानंतर २४ ते ३० तासांनंतरबिजांडातील प्रथम पेशी विभाजन पूर्ण होते.मायटोसीनच्या प्रक्रियेद्वारा एक पेशी दोन पेशीत आणि या प्रमाणे दोन पेशी चारपेशीत विभाजित होतात.

Early Pregnancy Factor (EPF)

गर्भधानानंतर २४ ते ४८ तासांनी आईच्या रक्तात ''प्रारंभिक गर्भावस्थेचे घटक'' असलेलया हारमोनच्या उपस्थिती द्वारागर्भावस्थेचे निदान करता येते.

 

 


[13] Quote from Moore and Persaud, 2003, 16; From O’Rahilly and Müller, 1987, 9: “Fertilization is the procession of events that begins when a spermatozoon makes contact with an oocyte or its investments and ends with the intermingling of maternal and paternal chromosomes at metaphase of the first mitotic division of the zygote.“ See Carlson, 2004, 3; O’Rahilly and Müller, 2001, 8. [Carnegie Stage 1]
[14]O’Rahilly and Müller, 2001, 25: “The term ‘egg’ should be discarded from human embryology.“ From O’Rahilly and Müller, 1987, 9: “The term ‘egg’ is best reserved for a nutritive object frequently seen on the breakfast table.“
[15]O’Rahilly and Müller, 2001, 23-24.
[16]O’Rahilly and Müller, 2001, 30.
[17]Dorland and Bartelmez, 1922, 372; Gasser, 1975, 1; Mall, 1918, 421; O’Rahilly and Müller, 2001, 31.
[18]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 33.
[19] Quote from Saunders, 1970, 1; Spraycar, 1995, 1976.
[20]Guyton and Hall, 2000, 34.
[21]Guyton and Hall, 2000, 24; Watson and Crick, 1953, 737.
[22]Guyton and Hall, 2000, 24; Lodish et al., 2000, 103; Watson and Crick, 1953, 737.
[23]Lodish et al., 2000, 456.
[24] See Appendix A.
[25] See Appendix A; Alberts et al., 1998, 189.
[26] See Appendix A.
[27]Hertig, 1968, 26; Hertig and Rock, 1973, 130; (cited by O’Rahilly and Müller, 1987, 12); Shettles, 1958, 400.
[28]Guyton and Hall, 2000, 34.
[29]Moore and Persaud, 2003, 33 & 60; Morton et al., 1992, 72; Nahhas and Barnea, 1990, 105.

Page 4


Chapter 5   Early Stages (Morula and Blastocyst) and Stem Cells

By 3 to 4 days after fertilization, the dividing cells of the embryo assume a spherical shape and the embryo is called a morula (mōr´ū-lă).[30]

By 4 to 5 days, a cavity forms within this ball of cells and the embryo is then called a blastocyst.[31]

The cells inside the blastocyst are called the inner cell mass and give rise to the head, body, and other structures vital to the developing human.[32]

Cells within the inner cell mass are called embryonic stem cells because they have the ability to form each of the more than 200 cell types contained in the human body.[33]

Chapter 5   Early Stages (Morula and Blastocyst) and Stem Cells

गर्भधानानंतर ३ ते ४ दिवसातगर्भाच्या विभाजित पेशी वर्तुळाकार धारण करतातआणि मग गर्भाला मोरुला (भ्रुण) म्हणतात.

४ ते ५ दिवसात या पेशींच्या गोळयात एक पोकळी निर्माण होतेआणि यानंतर गर्भास वलास्टोसीस्ट म्हणतात.

क्लास्टोसीस्ट मधील पेशींनाअंतस्थ पेशी द्रव्य म्हटले जाते ज्या पासून मस्तक, धड़ व विकसनशील मानवाकरिता महत्वाचे अन्य अवयव निर्माण होतात.

अंतस्थ पेशी द्रव्यामधील पेशींनागर्भीय स्टेम पेशी म्हटले जाते कारण मानवी देहात असणार्या २०० पेक्षा जास्त प्रकारच्या पेशी निर्माणकरण्याची त्यांच्यात क्षमता असते.

Chapter 6   1 to 1½ Weeks: Implantation and Human Chorionic Gonadotropin (hCG)

After traveling down the uterine tube, the early embryo embeds itself into the inner wall of the mother's uterus. This process, called implantation, begins 6 days and ends 10 to 12 days after fertilization.[34]

Cells from the growing embryo begin to produce a hormone called human chorionic gonadotropin (human kō-rē-on'ik gō'nad-ō-trō'pin), or hCG, the substance detected by most pregnancy tests.[35]

HCG directs maternal hormones to interrupt the normal menstrual cycle, allowing pregnancy to continue.[36]

Chapter 6   1 to 1½ Weeks: Implantation and Human Chorionic Gonadotropin (hCG)

गर्भाशयाच्या नलिकांत सरकल्यानंतरप्रारंभिक गर्भ आईच्या गर्भाशयाच्या आतील बाजुवर स्वतः स्थापित होतो.ही गर्भारोपण प्रक्रिया ६ दिवसात शुरू होतेआणि गर्भाधानानंतर १० ते १२ दिवसांत पूर्ण होते.

वाढत्या गर्भाच्या पेशी सुमन कोरीओनीक गोन्डोट्रोपिन नावाच्या हरमोनची अथवा बहुतेक गर्भावस्था परिक्षणात आढळणारा पदार्थएचसीजी निर्मिती करण्यास सुरवात करतात.

गर्भावस्था जारी राखण्याकरीता आईच्या हारमोनसना एचसीजी सामान्य मासिक पाळी थांबवण्या साठी प्रेरित करते.

Chapter 7   The Placenta and Umbilical Cord

Following implantation, cells on the periphery of the blastocyst give rise to part of a structure called the placenta (plă-sen'tă), which serves as an interface between the maternal and embryonic circulatory systems.

The placenta delivers maternal oxygen, nutrients, hormones, and medications to the developing human; removes all waste products; and prevents maternal blood from mixing with the blood of the embryo and fetus.[37]

The placenta also produces hormones and maintains embryonic and fetal body temperature slightly above that of the mother's.[38]

The placenta communicates with the developing human through the vessels of the umbilical (ŭm-bil'i-kăl) cord.[39]

The life support capabilities of the placenta rival those of intensive care units found in modern hospitals.

Chapter 7   The Placenta and Umbilical Cord

गर्भारोपणानंतरब्लास्टोसीस्टच्या परिधाच्या पेशीनाळेच्या निर्मितीस प्रारंभ करतात जीआईच्या आणि गर्भाच्या रक्ताभिसरण संस्थेमधे मध्यस्थ म्हणून कार्य करते.

नाळ मातृक प्राणवायु, पोषकतत्वे अंतर्स्त्राव आणि औषधी वाढत्या गर्भाला पोहचविते, सर्व मलमूत्र दूर करतेआणि आईच्या रक्ताला भ्रुण व गर्भाच्या रक्तात मिसळण्यापासून रोखते.

नाल हारमोनस सुद्धा निर्माण करतेआणि भ्रुण व गर्भाचे शारीरिक तापमानआईच्या शारीरिक तापमानापेक्षा किंचित जास्त राखते.

नाळ विकसनशील गर्भाशी गर्भनलीके द्वारा संपर्क राखते.

नाळेच्या जीवन संरक्षक क्षमता आधुनिक हॉस्पीटलमधील सघन चिकित्सा कक्षाच्या क्षमतेशी प्रतिस्पर्धा करतात.

 

 


[30]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 37; Spraycar, 1995, 1130: “Morula“ is derived from the Latin word morus meaning “mulberry.“ [Carnegie Stage 2]
[31]O’Rahilly and Müller, 2001, 39. [Carnegie Stage 3]
[32]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 39; Sadler, 2005, 6.
[33]Alberts et al., 1998, 32. For a discussion and definition of embryonic stem cells see the website of the National Institutes of Health: http://stemcells.nih.gov/infoCenter/stemCellBasics.asp#3
[34]O’Rahilly and Müller, 2001, 40; Implantation begins with attachment of the blastocyst at about 6 days after fertilization. [Attachment of the blastocyst to the inner wall of the uterus is a transient event and is the hallmark of Carnegie Stage 4.] See also Adams, 1960, 13-14; Cunningham et al., 2001, 20; Hamilton, 1949, 285-286; Hertig, 1968, 41; Hertig and Rock, 1944, 182; Hertig and Rock, 1945, 81 & 83; Hertig and Rock, 1949, 183; Hertig et al., 1956, 444. [Carnegie Stage 5]
[35]Chartier et al., 1979, 134; Cunningham et al., 2001, 27; O’Rahilly and Müller, 2001, 43.
[36]Cunningham et al., 2001, 20 & 26-27; O’Rahilly and Müller, 2001, 31.
[37]Hertig, 1968, 16; Cunningham et al., 2001, 86 & 136; For a detailed description of the placenta see Hamilton and Boyd, 1960. For a detailed description of the placenta vasculature see Harris and Ramsey, 1966. This separation of maternal and fetal blood is almost but not quite perfect as a small number of fetal cells may be found in the maternal circulation and vice-versa. See Cunningham et al., 2001, 96 & 136.
[38]Liley, 1972, 101; O’Rahilly and Müller, 2001, 78-79.
[39] For a detailed description of umbilical cord formation see Florian, 1930.

Page 5


Chapter 8   Nutrition and Protection

By 1 week, cells of the inner cell mass form two layers called the hypoblast and epiblast.[40]

The hypoblast gives rise to the yolk sac,[41] which is one of the structures through which the mother supplies nutrients to the early embryo.[42]

Cells from the epiblast form a membrane called the amnion (am-nē-on),[43] within which the embryo and later the fetus develop until birth.

Chapter 8   Nutrition and Protection

एक आठवडयानंतर, अंतस्थ पेशी पिंडाच्या पेशी हाईपोब्लास्ट आणि एपीब्लास्टनावांचे दोन आवरण-स्तरनिर्माण करतात.

हाईपोब्लास्ट चर्बीयुक्त आवरणनिर्माण करतो आई प्रारंभिक गर्भालापोषकतत्वांच्या पुरवठाज्या संरचनाद्वारा करतेत्यापैकी ते एक आहे.

एपीब्लास्टच्या पेशी अम्नीऑननावाचे गर्भावरण निर्माणकरतात, ज्यामधे भ्रुण व नंतर गर्भस्थ शिशुजन्मापर्यंत वाढतात.

Chapter 9   2 to 4 Weeks: Germ Layers and Organ Formation

By approximately 2½ weeks, the epiblast has formed 3 specialized tissues, or germ layers, called ectoderm, endoderm, and mesoderm.[44]

Ectoderm gives rise to numerous structures including the brain, spinal cord, nerves, skin, nails, and hair.

Endoderm produces the lining of the respiratory system and digestive tract and generates portions of major organs such as the liver and pancreas.

Mesoderm forms the heart, kidneys, bones, cartilage, muscles, blood cells, and other structures.[45]

By 3 weeks the brain is dividing into 3 primary sections called the forebrain, midbrain, and hindbrain.[46]

Development of the respiratory and digestive systems is also underway.[47]

As the first blood cells appear in the yolk sac,[48] blood vessels form throughout the embryo, and the tubular heart emerges.[49]

Almost immediately, the rapidly growing heart folds in upon itself as separate chambers begin to develop.[50]

The heart begins beating 3 weeks and 1 day following fertilization.[51]

The circulatory system is the first body system, or group of related organs, to achieve a functional state.[52]

Chapter 9   2 to 4 Weeks: Germ Layers and Organ Formation

ढोबळमानाने 2 1/2 आठवड्यापर्यन्तएपीब्लास्ट तीन विशेष पेशी-आवरण, निर्माण करतोज्यास एक्टोडर्म,एंडोडर्म,आणि मेसोडर्म म्हणतात.

एक्टोडर्मपासून अगणित संरचनानिर्माण होतातज्यात मेंदू,मज्जारज्जु, मज्जातंतु,त्वचा,नखे,आणि केसांचा समावेश आहे.

एन्डोडर्म श्वसनसंस्थेच्या आतील मृदू त्वचापचनसंस्थेचा मार्ग आणि यकृत व स्वादुपिंडासारख्या प्रमुख अवयवांच्या संरचनांची निर्मीती करते

मेसोडर्म हृदयाची किडनीहाडे,मृदूअस्थिस्नायुरक्तपेशीआणि अन्य संरचनांची निर्मिती करते.

तीन आठवडयानंतर मेन्दू तीन प्राथमिक हिश्शयात विभाजित होतोज्यांना अग्रमेंदू मध्यमेन्दू आणिमागीलमेन्दू म्हणतात.

श्वसन आणि पचनसंस्थेचा विकाससुरू असतो.

प्रथम रक्तपेशी चर्बीयुक्त आवरणत प्रकट होतातगर्भाच्या संपूर्ण शरीरातरक्तवाहिन्या स्थापित होतातआणि जवळजवळ लगेचच.

नलिकेच्या आकाराचे हृदय उभरतेभराभर वाढणारे हृदयआंत मुडपतेआणि त्यांत स्वतंत्र कप्पेविकसीत होण्यास सुरवात होते.

फलिती करणाचे पाठोपाठतीन आठवडे आणि एक दिवसानंतरहृदयाचे स्पंदन होण्यास सुरवात होते.

रक्ताभिसरण संस्था क्रियाशील होणारीप्रथम शारीरिक संस्था किंवा संबंधित अवयवांचा समूच्चय आहे.

Chapter 10   3 to 4 Weeks: The Folding of the Embryo

Between 3 and 4 weeks, the body plan emerges as the brain, spinal cord, and heart of the embryo are easily identified alongside the yolk sac.

Rapid growth causes folding of the relatively flat embryo.[53] This process incorporates part of the yolk sac into the lining of the digestive system and forms the chest and abdominal cavities of the developing human.[54]

Chapter 10   3 to 4 Weeks: The Folding of the Embryo

तीन ते चार आठवडयांचे मधेशरीराची रचना सुस्पष्ट होते कारण,मेंदू, मज्जारज्जू,आणि चर्बीच्या आवरणांच्या बाजूलागर्भाचे हृदयसहजपजे ओळखू येते.

गतीमान विकासामुळे सापेक्षतः सपाट गर्भ गोलाकार होतो. ह्या प्रक्रियेत चर्बीच्या पिशवीचा हिस्सापाचनसंस्थेच्या अंतस्थ आवरणांतरूपांतरीत होतो आणि वाढणाया गर्भाचीछाती व पोटातील पोकळीतयार होते.

 

 


[40]O’Rahilly and Müller, 2001, 39.
[41]Moore and Persaud, 2003, 50; O’Rahilly and Müller, 2001, 82. [Carnegie Stages 5 & 6]; In humans, the term “yolk sac“ has fallen out of favor among some embryologists (including O’Rahilly and Müller) because it is not a nutrient reservoir and does not contain yolk. The technically preferred term is umbilical vesicle. This structure plays a vital role in the transfer of nutrients from mother to embryo before placental circulation becomes fully functional.
[42]Campbell et al., 1993, 756; Kurjak et al., 1994, 437; O’Rahilly and Müller, 2001, 82.
[43]O’Rahilly and Müller, 1987, 29; O’Rahilly and Müller, 2001, 43. [Carnegie Stages 4-5]
[44]O’Rahilly and Müller, 2001, 14 & 135. [Carnegie Stage 7]; It should be noted there are many examples of organs derived from multiple germ layers. For instance, the liver is largely derived from endoderm but contains blood vessels and blood cells derived from mesoderm and nerves of ectodermal origin.
[45]Moore and Persaud, 2003, 80 & 83; Sadler, 2005, 9.
[46]Bartelmez, 1923, 236; Müller and O’Rahilly, 1983, 419-420 & 429; O’Rahilly and Gardner, 1979, 123 & 129; O’Rahilly and Müller, 1984, 422; O’Rahilly and Müller, 1987, 90; O’Rahilly and Müller, 1999a, 47 & 52. [Carnegie Stage 9]
[47]DiFiore and Wilson, 1994, 221; Fowler et al., 1988, 793; Grand et al., 1976, 793-794 & 796 & 798; O’Rahilly, 1978, 125; O’Rahilly and Boyden, 1973, 238-239; O’Rahilly and Müller, 1984, 421; O’Rahilly and Tucker, 1973, 6 & 8 & 23; Streeter, 1942, 232 & 235.
[48]Carlson, 2004, 117.
[49]Gilmour, 1941, 28; O’Rahilly and Müller, 1987, 86. [Carnegie Stage 9]
[50]Campbell, 2004, 14; Carlson, 2004, 116 & 446; Navaratnam, 1991, 147-148; O’Rahilly and Müller, 1987, 99. [Carnegie Stage 10]
[51]Campbell, 2004, 14; Carlson, 2004, 430; De Vries and Saunders, 1962, 96; Gardner and O’Rahilly, 1976, 583; Gilbert-Barness and Debich-Spicer, 1997, 650; Gittenger-de Groot et al., 2000, 17; van Heeswijk et al., 1990, 151; Kurjak and Chervenak, 1994, 439; Navaratnam, 1991, 147-148; O’Rahilly and Müller, 1987, 99; Wisser and Dirschedl, 1994, 108. [Carnegie Stage 10, possibly late Stage 9]
[52]Moore and Persaud, 2003, 70: “The cardiovascular system is the first organ system to reach a functional state.“
[53]Moore and Persaud, 2003, 78.
[54]Gasser, 1975, 26; Moore and Persaud, 2003, 78.

Page 6


प्रसूतिपूर्व विकासाचे जीवशास्त्र

The Biology of Prenatal Development
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Embryonic Development: 4 to 6 Weeks

Chapter 11   4 Weeks: Amniotic Fluid

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Table of Contents

  • THE EMBRYONIC PERIOD (THE FIRST 8 WEEKS)
  • THE FETAL PERIOD (8 WEEKS THROUGH BIRTH)
    • Chapter 37 – 9 Weeks: Swallows, Sighs, and Stretches
    • Chapter 38 – 10 Weeks: Rolls Eyes and Yawns, Fingernails & Fingerprints
    • Chapter 39 – 11 Weeks: Absorbs Glucose and Water
    • Chapter 40 – 3 to 4 Months (12 to 16 Weeks): Taste Buds, Jaw Motion, Rooting Reflex, Quickening
    • Chapter 41 – 4 to 5 Months (16 to 20 Weeks): Stress Response, Vernix Caseosa, Circadian Rhythms
    • Chapter 42 – 5 to 6 Months (20 to 24 Weeks): Responds to Sound; Hair and Skin; Age of Viability
    • Chapter 43 – 6 to 7 Months (24 to 28 Weeks): Blink-Startle; Pupils Respond to Light; Smell and Taste
    • Chapter 44 – 7 to 8 Months (28 to 32 Weeks): Sound Discrimination, Behavioral States
    • Chapter 45 – 8 to 9 Months (32 to 36 Weeks): Alveoli Formation, Firm Grasp, Taste Preferences
    • Chapter 46 – 9 Months to Birth (36 Weeks through Birth)
    •  
  • APPENDIX A − CALCULATIONS
  • APPENDIX B − RELATING EMBRYONIC AGE & STAGE
  • Bibliography
  • Full Names of Journals Cited
  • Program Index


All embryonic and fetal ages in this program refer to the time since fertilization.
Ages from 4 through 8 weeks are estimated to ±3 days.
Ages from 8 through 12 weeks are estimated to ±5 days.
Ages from 12 weeks through birth are generally estimated to ±1 week.
To simplify age calculations, the term “month“ assumes a 4-week period.
Age and stage conventions adopted during the embryonic period are listed in Appendix B.


English / ગુજરા [Gujarati]



Chapter 1   Introduction

The dynamic process by which the single-cell human zygote(zī΄gōt)[1] becomes a 100 trillion (1014) cell adult[2] is perhaps the most remarkable phenomenon in all of nature.

Researchers now know that many of the routine functions performed by the adult body become established during pregnancy – often long before birth.[3]

The developmental period before birth is increasingly understood as a time of preparation during which the developing human acquires the many structures, and practices the many skills, needed for survival after birth.

Chapter 1   Introduction

એક ગતિશીલ પ્રક્રિયામાં જેના અન્વયે એક કોષી માનવ ઝાયગોટ૧૦૦-ટ્રિલિયન કોષ વયસ્ક બને છે, જે કદાચસમગ્ર કુદરતનું સૌથી વધુ નોંધપાત્ર લક્ષણ છે.

સંશોધકો હવે જાણે છે કે ધણાં રોજિંદા કાર્યોવયસ્ક શરીર દ્વારા બજાવાતાંસગર્ભાવસ્થા દરમિયાન સ્થિર બને છેઆવું ઘણીવાર જન્મના ઘણા વખત પહેલાં થાય છે.

જન્મ પહેલાંનો વિકાસલક્ષી ગાળોતૈયારીના સમયે વધુને વધુ સમજાય છે,જે દરમિયાન વિકાસ પામતો મનુષ્યઘણી સંરચનાઓ પ્રાપ્ત કરે છે,અને ઘણી કુશળતાઓ વ્યવહારમાં મૂકે છે,જે જન્મ પછીના અનુજીવન માટે જરૂરી બને છે

Chapter 2   Terminology

Pregnancy in humans normally lasts approximately 38 weeks[4] as measured from the time of fertilization,[5] or conception,[6] until birth.

During the first 8 weeks following fertilization, the developing human is called an embryo,[7] which means "growing within."[8] This time, called the embryonic period,[9] is characterized by the formation of most major body systems.[10]

From the completion of 8 weeks until the end of pregnancy, "the developing human is called a fetus," which means "unborn offspring." During this time, called the fetal period, the body grows larger and its systems begin to function.[11]

All embryonic and fetal ages in this program refer to the time since fertilization.[12]

Chapter 2   Terminology

મનુષ્યમાં ગર્ભાવસ્થા સામાન્ય રીતે ૩૮ અઠવાડિયા રહે છેજેની ગણતરી ગર્ભાધાનના સમયથી,અથવા ગર્ભધારણના સમયથી, જન્મ સુધી હોય છે

ગર્ભાધાન પછીના પ્રથમ ૮ અઠવાડિયા દરમિયાન,વિકસતા મનુષ્ય ને 'ગર્ભ' કહેવામાં આવે છે,જેનો અર્થ "અંદર થતી વૃઘ્ધિ" થાય છે.આ સમય, જેને ગર્ભકાળ કહેવાય છેજેનું વર્ણન, રચના ઘ્વારા થતાંસૌથી મહત્વપૂર્ણ શરીર વ્યવસ્થાની રચનાથી કરાય છે.

આઠ અઠવાડિયાથી શરૂ કરીને ગર્ભાવસ્થા પૂરી ન થાય ત્યાં સુધી,"માણસનો વિકાસ થતો રહે છે, જેને 'ગર્ભ' કહે છે",જેનો અર્થ "વણજન્મેલ બાળક" થાય છે.આ સમય, જેને 'ગર્ભાવસ્થા' કહે છેતયારે શરીર મોટું થાય છે અને તેની સિસ્ટમ કામ કરવાનું શરૂ કરે છે.

ગર્ભાધાન અને ગર્ભાવસ્થાના વયકાળના આ કાર્યક્રમમાંગર્ભાધાનના સમયથી ઉલ્લેખ કરાય છે.

 

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[1]Gasser, 1975, 1.
[2]Guyton and Hall, 2000, 2; Lodish et al., 2000, 12.
[3]Vindla and James, 1995, 598.
[4]Cunningham et al., 2001, 226; O’Rahilly and Müller, 2001, 92.
[5]O’Rahilly and Müller, 1987, 9.
[6]Spraycar, 1995, 377 & 637.
[7]O’Rahilly and Müller, 2001, 87.
[8] Quote from Ayto, 1990, 199.
[9] Human development during the 8-week embryonic period has been divided into a series of 23 stages called Carnegie Stages. These stages are well described in O’Rahilly and Müller, 1987. Because human growth is unique and dependent on multiple factors, different embryos may reach a certain developmental milestone or a certain size at slightly different ages. This internationally-accepted staging system provides a way to describe development independent of age and size. Each of the 23 Carnegie Stages has specific structural features. As we describe various milestones of development, the Carnegie Stage at which they occur will be noted by a designation such as: [Carnegie Stage 2]. See Appendix B for additional information relating embryonic staging and age assignments.
[10]Moore and Persaud, 2003, 3.
[11] Quotes from Moore and Persaud, 2003, 3: “After the embryonic period (eight weeks), the developing human is called a fetus.“ Also see O’Rahilly and Müller, 2001, 87.
[12] This convention, termed “postfertilization age“ by O’Rahilly, has been long preferred by embryologists. [see Mall, 1918, 400; O’Rahilly and Müller, 1999b, 39; O’Rahilly and Müller, 2001, 88 & 91.] Obstetricians and radiologists typically assign age based on the time elapsed since the first day of the last menstrual period prior to fertilization. This is correctly termed “postmenstrual age“ and begins 2 weeks before fertilization occurs. To summarize: postmenstrual age = postfertilization age + 2 weeks. Therefore, postmenstrual age equals approximately 2 weeks at the time of fertilization. The commonly used term “gestational age“ has been used with both age conventions and is best either avoided or carefully defined with each use.

Page 3


The Embryonic Period (The First 8 Weeks)

Embryonic Development: The First 4 Weeks

Chapter 3   Fertilization

Biologically speaking, "human development begins at fertilization,"[13] when a woman and a man each combine 23 of their own chromosomes through the union of their reproductive cells.

A woman's reproductive cell is commonly called an "egg" but the correct term is oocyte (ō´ō-sīt).[14]

Likewise, a man's reproductive cell is widely known as a "sperm," but the preferred term is spermatozoon (sper´mă-tō-zō´on).[15]

Following the release of an oocyte from a woman's ovary in a process called ovulation (ov´yū-lā´shŭn),[16] the oocyte and spermatozoon join within one of the uterine tubes,[17] which are often referred to as Fallopian tubes.

The uterine tubes link a woman's ovaries to her uterus or womb.

The resulting single-celled embryo is called a zygote,[18] meaning "yoked or joined together."[19]

The Embryonic Period (The First 8 Weeks)

Embryonic Development: The First 4 Weeks

Chapter 3   Fertilization

જીવશાસ્ત્રના ધોરણે કહીએ તો,"મનુષ્યનો વિકાસ ગર્ભાધાનકાળથી શરૂ થાય છે",જયારે સ્ત્રી અને પુરૂષદરેકના તેમના પોતાના ૨૩ રંગસૂત્રોનું સંયોજનપુનર્રચનાત્મક કોશોના એકીકરણ ઘ્વારા થાય છે.

સ્ત્રીના પુનર્રચનાત્મક કોશને સામાન્ય રીતે "અંડબીજ" કહે છેપરંતુ સાચો શબ્દ 'ઓકાઈટ/બીજાંડ' છે.

તે જ પ્રમાણે, પુરૂષનો પુનર્રચનાત્મક કોષવ્યાપકપણે 'શુક્રાણુ' તરીકે જાણીતો છેપરંતુ પસંદગીપાત્ર શબ્દ 'સ્પર્મેટૉઝૉન / શુક્રજંતુ' છે.

સ્ત્રીના ગર્ભાશયમાંથી ઓકાઈટ છુટા પડે છેજે પ્રક્રિયાને (ઓવ્યુલેશન) અંડમોચન કહેવાય છે,જેમાં બીજાંડ અને શુક્રાણુગર્ભાશયની એક નળીની અંદર જોડાય છે,જે નળીને ઘણીવાર ફેલોપિન ટયુબ કહે છે.

ગર્ભાશયની નળી સ્ત્રીના અંડાશયનેતેના ગર્ભાશય સાથે જોડે છે

તેના પરિણામે નીપજતા એક કોશવાળા ગર્ભને ઝાયગોટ કહે છે,જેનો અર્થ 'જોડાયેલ' અથવા 'એકસાથે જોડાયેલ' એમ થાય છે.

Chapter 4   DNA, Cell Division, and Early Pregnancy Factor (EPF)

DNA

The zygote's 46 chromosomes[20] represent the unique first edition of a new individual's complete genetic blueprint. This master plan resides in tightly coiled molecules called DNA. They contain the instructions for the development of the entire body.

DNA molecules resemble a twisted ladder known as a double helix.[21] The rungs of the ladder are made up of paired molecules, or bases, called guanine, cytosine, adenine, and thymine.

Guanine pairs only with cytosine, and adenine with thymine.[22] Each human cell contains approximately 3 billion (3×109) base pairs.[23]

The DNA of a single cell contains so much information that if it were represented in printed words, simply listing the first letter of each base would require over 1.5 million (1.5×106) pages of text![24]

If laid end-to-end, the DNA in a single human cell measures 3⅓ feet or 1 meter.[25]

If we could uncoil all of the DNA within an adult's 100 trillion (1014) cells, it would extend over 63 billion (6.3×1010) miles. This distance reaches from the earth to the sun and back 340 times.[26]

Cell Division

Approximately 24 to 30 hours after fertilization, the zygote completes its first cell division.[27] Through the process of mitosis, one cell splits into two, two into four, and so on.[28]

Early Pregnancy Factor (EPF)

As early as 24 to 48 hours after fertilization begins, pregnancy can be confirmed by detecting a hormone called "early pregnancy factor" in the mother's blood.[29]

Chapter 4   DNA, Cell Division, and Early Pregnancy Factor (EPF)

DNA

જનીન તત્વોના 'ઝાયગોટ' 46 રંગસૂત્રો,અદ્વિતિય પ્રથમ આવૃતિ દર્શાવે છે.જે નવી વ્યકિતની સંપૂર્ણ પ્રજનની બ્લ્યુપ્રિન્ટ હોય છેઆ બૃહદ યોજનાસખ્ત રીતે વિંટળાયેલ ડીએનએ કહેવાતા અણુમાં રહે છેતેમાં સમાવિષ્ટ હોય છેસમગ્ર શરીરની વિકાસની સૂચનાઓ

ડીએનએ અણુઓ વળ ચઢાવેલ નિસરણી જેવા હોય છે,જે બેવડા ગૂંચળા તરીકે ઓળખાય છે.નિસરણીમાં પગથિયાં જોડીબંધ અણુઓથી,અથવા મિશ્ર તત્વમાંથી બને છે, જે ગ્યુઆનિન,સાયટોસિન, એડેનિન અને થાયમીન તરીકે ઓળખાય છે

ગ્યુઆનિન માત્ર સાયટોસિન સાથે જોડી કરે છે,અને એડેનિન થાયમીન સાથે જોડાય છે.દરેક માનવ-કોષોમાં અંદાજે 3 અબજઆવા બેઝ કોષો હોય છે.

એક કોષના ડીએનએમાં એટલી બધી માહિતી હોય છે કે,તેને મુદ્રિત શબ્દોમાં રજુ કરવામાં આવે તો,ખાલી દરેક બેઝનાં માત્ર પ્રથમ અક્ષર વર્ણવીએ તો,તેને માટે પુસ્તકના ૧પ લાખ પૃષ્ઠો જરુરી બને!

તેને છેડાથી છેડા સુધી મુકવામાં આવે તો,એક મનુષ્ય કોષમાં ડીએનએ નું માપ ૩ ૧/૩ ફુટઅથવા ૧ મીટર થાય.

આપણે તમામ ડીએનએ ઉકેલીએ તોએક વયસ્કના ૧૦૦ ટ્રિલિયન કોષોમાં,તે ૬૩ અબજ માઈલ સુધી વિસ્તરે.આ અંતર પૃથ્વી થી સૂર્ય અને ત્યાંથી પાછા ફરતાં,૩૪૦ ગણું થાય.

Cell Division

ફલન થયા પછી અંદાજે ૨૪ થી ૩૦ કલાકે,ઝાયગોટ જનીન તેનું પ્રથમ કોષ વિભાજન પુરૂ કરે છે.સાલ્વિક વિભાજન (માઇટોસીસ) પ્રક્રિયા ધ્વારા,એક કોષનું બે માં, બે નું ચારમાં, એમ આગળ વિભાજન થતું રહે છે.

Early Pregnancy Factor (EPF)

ગર્ભાધાન શરૂ થયા પછી ૨૪ થી ૪૮ કલાકમાં બને તેટલું જલદી,હોમોર્નની શોધતપાસ ધ્વારા ગર્ભાવસ્થા નક્કી કરી શકાય છે,જેને માતાના લોહીમાં 'પ્રારંભિક ગર્ભાવસ્થા પરિબળ' કહે છે.

 

 


[13] Quote from Moore and Persaud, 2003, 16; From O’Rahilly and Müller, 1987, 9: “Fertilization is the procession of events that begins when a spermatozoon makes contact with an oocyte or its investments and ends with the intermingling of maternal and paternal chromosomes at metaphase of the first mitotic division of the zygote.“ See Carlson, 2004, 3; O’Rahilly and Müller, 2001, 8. [Carnegie Stage 1]
[14]O’Rahilly and Müller, 2001, 25: “The term ‘egg’ should be discarded from human embryology.“ From O’Rahilly and Müller, 1987, 9: “The term ‘egg’ is best reserved for a nutritive object frequently seen on the breakfast table.“
[15]O’Rahilly and Müller, 2001, 23-24.
[16]O’Rahilly and Müller, 2001, 30.
[17]Dorland and Bartelmez, 1922, 372; Gasser, 1975, 1; Mall, 1918, 421; O’Rahilly and Müller, 2001, 31.
[18]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 33.
[19] Quote from Saunders, 1970, 1; Spraycar, 1995, 1976.
[20]Guyton and Hall, 2000, 34.
[21]Guyton and Hall, 2000, 24; Watson and Crick, 1953, 737.
[22]Guyton and Hall, 2000, 24; Lodish et al., 2000, 103; Watson and Crick, 1953, 737.
[23]Lodish et al., 2000, 456.
[24] See Appendix A.
[25] See Appendix A; Alberts et al., 1998, 189.
[26] See Appendix A.
[27]Hertig, 1968, 26; Hertig and Rock, 1973, 130; (cited by O’Rahilly and Müller, 1987, 12); Shettles, 1958, 400.
[28]Guyton and Hall, 2000, 34.
[29]Moore and Persaud, 2003, 33 & 60; Morton et al., 1992, 72; Nahhas and Barnea, 1990, 105.

Page 4


Chapter 5   Early Stages (Morula and Blastocyst) and Stem Cells

By 3 to 4 days after fertilization, the dividing cells of the embryo assume a spherical shape and the embryo is called a morula (mōr´ū-lă).[30]

By 4 to 5 days, a cavity forms within this ball of cells and the embryo is then called a blastocyst.[31]

The cells inside the blastocyst are called the inner cell mass and give rise to the head, body, and other structures vital to the developing human.[32]

Cells within the inner cell mass are called embryonic stem cells because they have the ability to form each of the more than 200 cell types contained in the human body.[33]

Chapter 5   Early Stages (Morula and Blastocyst) and Stem Cells

ગર્ભાધાનના ૩ થી ૪ દિવસ બાદ,ગર્ભના વિભાજક કોષો ગોળ આકાર ધારણ કરે છેઅને ગર્ભને "મોરૂલા" કહે છે.

૪ થી ૫ દિવસમાં, કોષોના આ ગોળ આકારમાં પોલાણ બને છે.અને ગર્ભ ત્યારપછી બ્લાસ્ટોસિસ્ટ કહેવાય છે.

બ્લાસ્ટોસિસ્ટના કોષોને,આંતરિક કોષ દ્રવ્ય કહેવાય છે,અને માથું, શરીર તથા બીજા ભાગોની રચના કરે છે,જે મનુષ્યને વિકસાવવામાં મહત્વપૂર્ણ છે.

આંતરિક કોષ દ્રવ્યની અંદરના કોષોનેગર્ભાવસ્થાના સ્ટેમ-સેલ કહે છે, કારણકે તેઓદરેકમાં ૨૦૦ કરતાં વધુ કોષ પ્રકારો પેદા કરવાની શક્તિ હોય છે,જે મનુષ્યના શરીરમાં રહેલાં છે.

Chapter 6   1 to 1½ Weeks: Implantation and Human Chorionic Gonadotropin (hCG)

After traveling down the uterine tube, the early embryo embeds itself into the inner wall of the mother's uterus. This process, called implantation, begins 6 days and ends 10 to 12 days after fertilization.[34]

Cells from the growing embryo begin to produce a hormone called human chorionic gonadotropin (human kō-rē-on'ik gō'nad-ō-trō'pin), or hCG, the substance detected by most pregnancy tests.[35]

HCG directs maternal hormones to interrupt the normal menstrual cycle, allowing pregnancy to continue.[36]

Chapter 6   1 to 1½ Weeks: Implantation and Human Chorionic Gonadotropin (hCG)

નીચે ગર્ભ નળી સુધી મુસાફરી કર્યા પછી,પ્રારંભિક ગર્ભ પોતાનેમાતાના ગર્ભની અંદરની દિવાલમાં સ્થિર કરે છેઆ પ્રક્રિયાને, રોપણ ક્રિયા કહે છે, જે છ દિવસમાં શરૂ થાયઅને ગર્ભાધાન પછી ૧૦ થી ૧૨ દિવસમાં પૂરી થાય.

વૃધ્ધિ પામતાં ગર્ભમાંથી કોષો હાર્મોન પેદા કરવાનું શરૂ કરે છેજેને કોરિયોનીક ગોનાડોટ્રોપિન, અથવા એચસીજી કહે છે,જે દ્રવ્ય, મોટાભાગના ગર્ભાવસ્થા પરીક્ષણમાં શોધાયું હતું.

એચસીજી માતૃત્વ હાર્મોનનેરાબેતા મુજબ માસિક સત્રમાં, અવરોધ ઉભો કરવાનો આદેશ આપીગર્ભાવસ્થા ચાલુ રાખવા દે છે.

Chapter 7   The Placenta and Umbilical Cord

Following implantation, cells on the periphery of the blastocyst give rise to part of a structure called the placenta (plă-sen'tă), which serves as an interface between the maternal and embryonic circulatory systems.

The placenta delivers maternal oxygen, nutrients, hormones, and medications to the developing human; removes all waste products; and prevents maternal blood from mixing with the blood of the embryo and fetus.[37]

The placenta also produces hormones and maintains embryonic and fetal body temperature slightly above that of the mother's.[38]

The placenta communicates with the developing human through the vessels of the umbilical (ŭm-bil'i-kăl) cord.[39]

The life support capabilities of the placenta rival those of intensive care units found in modern hospitals.

Chapter 7   The Placenta and Umbilical Cord

રોપણ પ્રક્રિયા બાદ,બ્લાસ્ટોસિસ્ટના પરિધ પરના કોષોએક સંરચના ના ભાગ નો ઉદભવ કરે છે જે પ્લેસેન્ટા તરીકે ઓળખાય છે,જે આંતર સપાટી તરીકે,માતાની અને ગર્ભની ચક્રાકાર વ્યવસ્થા વચ્ચે કામ આપે છે.

ગર્ભનું વેષ્ટન (ઓર) માતાના ઓકિસજન, પોષક તત્વોહોમોર્ન અને ઉપચાચારાત્મક તત્વો વિકસતાં માનવ શરીરને પહોચાડે છે;તમામ નકામી પેદાશો દૂર કરે છે;અને માતાને લોહીને મિશ્ર થતુ અટકાવે છે,ગર્ભ અને ભૃણના લોહીની સાથે.

ગર્ભનું વેષ્ટન હાર્મોન પણ પેદા કરે છે, અનેગર્ભ તથા ભૃણના શરીરને,માતા કરતાં સહેજ ઉંચા ઉષ્ણતામાને જાળવે છે.

વેષ્ટન, વિકસતા મનુષ્ય સાથે સંચાર કરે છે,નાળની લોહી વગેરે લઈ જતી નળી મારફત.

ગર્ભ વેષ્ટનની જીવન આધાર ક્ષમતાઓ,આધુનિક હોસ્પિટલોમાં મળતાં સધન સંભાળ સાથે ર્સ્પધા કરે છે.

 

 


[30]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 37; Spraycar, 1995, 1130: “Morula“ is derived from the Latin word morus meaning “mulberry.“ [Carnegie Stage 2]
[31]O’Rahilly and Müller, 2001, 39. [Carnegie Stage 3]
[32]Gasser, 1975, 1; O’Rahilly and Müller, 2001, 39; Sadler, 2005, 6.
[33]Alberts et al., 1998, 32. For a discussion and definition of embryonic stem cells see the website of the National Institutes of Health: http://stemcells.nih.gov/infoCenter/stemCellBasics.asp#3
[34]O’Rahilly and Müller, 2001, 40; Implantation begins with attachment of the blastocyst at about 6 days after fertilization. [Attachment of the blastocyst to the inner wall of the uterus is a transient event and is the hallmark of Carnegie Stage 4.] See also Adams, 1960, 13-14; Cunningham et al., 2001, 20; Hamilton, 1949, 285-286; Hertig, 1968, 41; Hertig and Rock, 1944, 182; Hertig and Rock, 1945, 81 & 83; Hertig and Rock, 1949, 183; Hertig et al., 1956, 444. [Carnegie Stage 5]
[35]Chartier et al., 1979, 134; Cunningham et al., 2001, 27; O’Rahilly and Müller, 2001, 43.
[36]Cunningham et al., 2001, 20 & 26-27; O’Rahilly and Müller, 2001, 31.
[37]Hertig, 1968, 16; Cunningham et al., 2001, 86 & 136; For a detailed description of the placenta see Hamilton and Boyd, 1960. For a detailed description of the placenta vasculature see Harris and Ramsey, 1966. This separation of maternal and fetal blood is almost but not quite perfect as a small number of fetal cells may be found in the maternal circulation and vice-versa. See Cunningham et al., 2001, 96 & 136.
[38]Liley, 1972, 101; O’Rahilly and Müller, 2001, 78-79.
[39] For a detailed description of umbilical cord formation see Florian, 1930.

Page 5


Chapter 8   Nutrition and Protection

By 1 week, cells of the inner cell mass form two layers called the hypoblast and epiblast.[40]

The hypoblast gives rise to the yolk sac,[41] which is one of the structures through which the mother supplies nutrients to the early embryo.[42]

Cells from the epiblast form a membrane called the amnion (am-nē-on),[43] within which the embryo and later the fetus develop until birth.

Chapter 8   Nutrition and Protection

એક અઠવાડીયા સુધીમાં,આંતરિક દ્રવ્ય કોષના કોષો,બે સ્તરોની રચના કરે છે,જેને હાઈપોબ્લાસ્ટ અનેઅને એપીબ્લાસ્ટ કહે છે.

હાયપોબ્લાસ્ટ'યોક સેક' પેદા કરે છેજે એક સરંચના છે જેના મારફતમાતા, પોષક તત્વોપ્રારંભિક ગર્ભને પહોચાડે છે.

એપિબ્લાસ્ટમાંથી નીકળતા કોષોઅંતસ્ત્રાવ (મેમ્બ્રેન) બનાવે છે, જેને આંતર ત્વચાનું આવરણ કહે છે,જેની અંદર ગર્ભઅને છેલ્લે ભૃણજન્મ સુધી વિકસે છે.

Chapter 9   2 to 4 Weeks: Germ Layers and Organ Formation

By approximately 2½ weeks, the epiblast has formed 3 specialized tissues, or germ layers, called ectoderm, endoderm, and mesoderm.[44]

Ectoderm gives rise to numerous structures including the brain, spinal cord, nerves, skin, nails, and hair.

Endoderm produces the lining of the respiratory system and digestive tract and generates portions of major organs such as the liver and pancreas.

Mesoderm forms the heart, kidneys, bones, cartilage, muscles, blood cells, and other structures.[45]

By 3 weeks the brain is dividing into 3 primary sections called the forebrain, midbrain, and hindbrain.[46]

Development of the respiratory and digestive systems is also underway.[47]

As the first blood cells appear in the yolk sac,[48] blood vessels form throughout the embryo, and the tubular heart emerges.[49]

Almost immediately, the rapidly growing heart folds in upon itself as separate chambers begin to develop.[50]

The heart begins beating 3 weeks and 1 day following fertilization.[51]

The circulatory system is the first body system, or group of related organs, to achieve a functional state.[52]

Chapter 9   2 to 4 Weeks: Germ Layers and Organ Formation

અંદાજે ૨૧/ર અઠવાડીયા પછીએપીબ્લાસ્ટે,ત્રણ ખાસ પેશીઓ બનાવેલ છે,અથવા જીવાંશ /સૂક્ષ્મ જીવના થર,જેને એકટોડર્મ,એન્ડોડર્મ અનેમીસોડર્મ કહે છે.

એકટોડર્મશરીરના અનેક ભાગોની રચના રે છેજેમકે મગજ,કરોડરજજુ,જ્ઞાનતંતુઓ,ચામડી,નખ,અને વાળની.

એન્ડોડર્મ શ્વસન તંત્રની અંદરનો ભાગતથા પાચનતંત્રનો માર્ગ બનાવે છે,અને મહત્વના અવયવોના ભાગ બનાવે છે,જેમ કે, પિત્તાશય,અને સ્વાદુપિંડ.

મેસોડર્મ, હૃદય, કિડની,હાડકાં,કોમલાસ્થિ,સ્નાયુઓ,લોહીના કોષો,અને બીજી સરંચના બનાવે છે.

3 અઠવાડીયામાં સુધીમાંમગજનું ત્રણ મુખ્ય વિભાગોમાં વિભાજન થાય છેતેને આગલું મગજ,મઘ્ય મગજ,અને પાછલું મગજ.

શ્વસનતંત્ર અને પાચનતંત્રનો વિકાસપણ ચાલુ રહે છે.

જ્યારે પ્રથમ લોહીના કોષો,'યોક સેક'માં દેખાતા થતા,લોહીની નળીઓની રચનાસમગ્ર ગર્ભ માં થાય છે,અને નળીઓવાળું હૃદય ઉદભવે છે.

લગભગ એકદમ ઝડપથીવિકસતું હૃદયતેના પર ગડી કરે છે,જ્યારે અલગ અલગ ચેમ્બરવિકસવાનું શરૂ થાય છે.

હૃદયના ધબકારા ગર્ભધાનથી૩ અઠવાડીયા અને ૧ દિવસપછી શરૂ થાય છે.

ચક્રાકાર વ્યવસ્થા તંત્ર એ શરીરનું,અથવા સંબંધિત અંગોના જૂથનું પ્રથમ વ્યવસ્થા તંત્ર છે,જે કાર્યલક્ષી સ્થિતિ પ્રાપ્ત કરે છે.

Chapter 10   3 to 4 Weeks: The Folding of the Embryo

Between 3 and 4 weeks, the body plan emerges as the brain, spinal cord, and heart of the embryo are easily identified alongside the yolk sac.

Rapid growth causes folding of the relatively flat embryo.[53] This process incorporates part of the yolk sac into the lining of the digestive system and forms the chest and abdominal cavities of the developing human.[54]

Chapter 10   3 to 4 Weeks: The Folding of the Embryo

3 અને 4 અઠવાડીયાની વચ્ચેશરીરની યોજના દેખાવા માંડે છેજ્યારે મગજ,કરોડરજજુ,અને ગર્ભના હદયયોક સેકની સાથોસાથસહેલાઈથી ઓળખી શકાય છે.

ઝડપી વિકાસને કારણેપ્રમાણમાં સપાટ ગર્ભમાં ગડી વળે છે.આ પ્રક્રિયામાં બને છે,યોક સેકનો એક ભાગ,અસ્તરપાચન તંત્રનું,અને તે વિકાસપામી રહેલ મનુષ્યનાં શરીરમાં છાતીઅને પેટનું પોલાણબનાવે છે.

 

 


[40]O’Rahilly and Müller, 2001, 39.
[41]Moore and Persaud, 2003, 50; O’Rahilly and Müller, 2001, 82. [Carnegie Stages 5 & 6]; In humans, the term “yolk sac“ has fallen out of favor among some embryologists (including O’Rahilly and Müller) because it is not a nutrient reservoir and does not contain yolk. The technically preferred term is umbilical vesicle. This structure plays a vital role in the transfer of nutrients from mother to embryo before placental circulation becomes fully functional.
[42]Campbell et al., 1993, 756; Kurjak et al., 1994, 437; O’Rahilly and Müller, 2001, 82.
[43]O’Rahilly and Müller, 1987, 29; O’Rahilly and Müller, 2001, 43. [Carnegie Stages 4-5]
[44]O’Rahilly and Müller, 2001, 14 & 135. [Carnegie Stage 7]; It should be noted there are many examples of organs derived from multiple germ layers. For instance, the liver is largely derived from endoderm but contains blood vessels and blood cells derived from mesoderm and nerves of ectodermal origin.
[45]Moore and Persaud, 2003, 80 & 83; Sadler, 2005, 9.
[46]Bartelmez, 1923, 236; Müller and O’Rahilly, 1983, 419-420 & 429; O’Rahilly and Gardner, 1979, 123 & 129; O’Rahilly and Müller, 1984, 422; O’Rahilly and Müller, 1987, 90; O’Rahilly and Müller, 1999a, 47 & 52. [Carnegie Stage 9]
[47]DiFiore and Wilson, 1994, 221; Fowler et al., 1988, 793; Grand et al., 1976, 793-794 & 796 & 798; O’Rahilly, 1978, 125; O’Rahilly and Boyden, 1973, 238-239; O’Rahilly and Müller, 1984, 421; O’Rahilly and Tucker, 1973, 6 & 8 & 23; Streeter, 1942, 232 & 235.
[48]Carlson, 2004, 117.
[49]Gilmour, 1941, 28; O’Rahilly and Müller, 1987, 86. [Carnegie Stage 9]
[50]Campbell, 2004, 14; Carlson, 2004, 116 & 446; Navaratnam, 1991, 147-148; O’Rahilly and Müller, 1987, 99. [Carnegie Stage 10]
[51]Campbell, 2004, 14; Carlson, 2004, 430; De Vries and Saunders, 1962, 96; Gardner and O’Rahilly, 1976, 583; Gilbert-Barness and Debich-Spicer, 1997, 650; Gittenger-de Groot et al., 2000, 17; van Heeswijk et al., 1990, 151; Kurjak and Chervenak, 1994, 439; Navaratnam, 1991, 147-148; O’Rahilly and Müller, 1987, 99; Wisser and Dirschedl, 1994, 108. [Carnegie Stage 10, possibly late Stage 9]
[52]Moore and Persaud, 2003, 70: “The cardiovascular system is the first organ system to reach a functional state.“
[53]Moore and Persaud, 2003, 78.
[54]Gasser, 1975, 26; Moore and Persaud, 2003, 78.

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પૂર્વ પ્રસૂતિ વિકાસનું જીવ વિજ્ઞાન

The Biology of Prenatal Development
DVD Documentation

[Features] [Tutorial]

English / .ગુજરા [Gujarati]

Embryonic Development: 4 to 6 Weeks

Chapter 11   4 Weeks: Amniotic Fluid

By 4 weeks the clear amnion surrounds the embryo in a fluid-filled sac.[55] This sterile liquid, called amniotic (am-nē-ot'ik) fluid

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