/anterior neuropore: closed by 25th days /posterior neuropore: closed by 27th days ---neural crest(mesoectoderm): two lines of cell cords→ganglion
---significance of fertilization: 1) a new life begin(initiation of cleavage) 2)restoration of the diploid number of
chromosomes: cross-over 3) determination of the sex of the new individual:
---decidual response of endometrium /stroma cell→predecidual cell→decidual cell(cell become larger and rich in glycogen and lipid droplet)
/endometrium →decidua: -decidua basalis -decidua capsularis -decidua parietalis
---processes of fertilization: 1) acrosome reaction: /hyaluronic acidase: dissolve corona radiate * interact with ZP3(receptor glycoprotein, exist in zona pellucide) molecules, release /acrosin: dissolve zona pellucide /enter perivitelline space
---conditions: 1) maturation of oocyte 2) maturation of spermatozoon: /ductus epididymus: 2-3 weeks, motility protein
forward
3) capacitation of spermatozoa:
decapacitation factor: exist in epididymus, to inhibit the release of acrosome enzymes
capacitation factor: secreted by epi. cells of oviduct, capacity of releasing acrosome enzymes
组织胚胎学课件
七年制英文医学班专用
中国医科大学
基础医学院
组胚—英文教学组
Chapter 21
General Embryology
---a science which study the processes and regulations of development of human fetus.(from 1 cell(zygote) to (5-7)X1012 cells )
1) cleavage and blastocyst formation ①cleavage ---blastomere: cells formed by cleavage /30h: 2 /40h: 4 /72h: 12-16- morula
②formation of blastocyst: by 5th day, blastomere reach to 107, small space appear between them
1.Fertilization
---definition: the process by which the male and female gametes(sperm and ovum) unite to give rise to zygote
---place: in the ampullary region of the fallopian tube
---blastocoele: filled with liquid
---trophoblast
---inner cell mass
---polar trophoblast
2) Implantation
---definition: the process by which the blastocyst is embedded in endometrium
4) quality and quantity of spermatozoa: 2-6 ml, 100,000,000/ml, <1.5 ml; or <10,000,000; abnormal sperm >30%; or capacity for mobile< 70%
5) meeting of sperm and ovum sperm: 20-24h ovum: 15-18h(1-3ds)
ova(22+X) + X-bearing spermatozoon = girl ova(22+X) + Y-bearing spermatozoon = boy *klinefelter’s syndrome: 47XXY, 48XXXY
2. Blastocyst formation and implantation
---mesoderm: intraembryonic mesoderm
---endoderm: hypoblast cells are replaced by epiblast cells
---ectoderm: epiblast changed the name into ectoderm
* trilaminar germ disc: endoderm + mesoderm + ectoderm
---epiblast: primary ectoderm /amniotic membrane: amnioblast /amniotic cavity /amniotic fluid /amnion
---hypoblast: primary endoderm
/extraembryonic endoderm→exocoelomic membrane→primary yolk sac → exocoelomic vesicle
2) formation of mesoderm: early of 3 weeks ---primitive streak: cells of epiblast proliferate to
form a longitudinal arranged cell cord ---primitive groove ---primitive node ---primitive pit
zona reaction: change of ZP3 molecules in zona pellucide
4) formation of zygote(fertilized ovum)
secondary meiosis complete: form second polar body
male pronucleus fuse with female pronucleus, to restore the 2n chromasome
2) spermatozoa fuse with the membrane of ovum: nucleus enter cytoplasm of ovum
3) monospermy:
cortical reaction: cortical granules(located in cytoplasm of ovum) are released into perivitelline space, and cause
① differentiation of ectoderm: from 18th –19th days ---neural plate: neuro-epithelium(neural ectoderm):
pseudostratified columnar epi. ---neural fold ---neural groove ---neural tube: →CNS
---time: 5th –6th day begin; 11th –12th day complete
---processes: zona pellucide disappear → polar trophoblast touch the endometrium→secrete proteolytase →dissolve the endometrium → embedded into endometrium→coagulation plug seal the come into two layers when blastocyst is embedding into endometrium syncytiotrophoblast cytotrophoblast
---place: /posterior wall of fundus and body of uterus placenta praevia ectopic pregnancy
---differentiation: same cells which are primordial and inmuture differentiate into different cells which have specific structure and function
---induction: some tissues effect the differentiation, and determine the differentiating orientation of another tissue