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General embryology (I). Jun Zhou (周俊) zhjjwm300@zju.edu.cn School of Medicine, Zhejiang University. 20180612. Histology & Embryology: Final score: Attendence (Lab , Lecture): 10% Quiz: 15% Lab test: 25% Final written exam.: 50%. Final written exam: Histology: 70-80%,
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General embryology (I) Jun Zhou(周俊) zhjjwm300@zju.edu.cn School of Medicine, Zhejiang University 20180612
Histology & Embryology: • Final score: • Attendence (Lab , Lecture): 10% • Quiz: 15% • Lab test: 25% • Final written exam.: 50% • Final written exam: • Histology: 70-80%, • Embryology: 20-30% • Item type: • Single choice: 50, 1 point/per (50%) • Filling the blank: 50, 0.5 point/per (25%) • Brief question: 5, 5 points/per (25%)
1. Langman’s Medical Embryology,13 th Edition 2.高英茂主编,《组织胚胎学》,全国八年制教材,人民卫生出版社,2010 3.课程网站:m-learning.zju.edu.cn, 2018组织胚胎学
OBJECTIVES • 1.说明受精的过程和意义。 • 2.试述胚胎植入的定义、过程、部位以及植入后的子宫蜕膜分部。 • 3.试述两胚层胚盘的形成过程和组成。 • 4.三胚层胚盘的形成和初步分化。 • 5.胎膜、蜕膜及胎盘的结构与功能。 • 6.先天性畸形。
末次月经的第一天 受精 受精龄, 266天 分娩 月经龄, 280天 • a science which study the processes and regulations of development of human fetus.(from 1 cell (zygote合子) to (5-7) x1012 cells) • total 38 weeks: 280 /266 days
preembryonic period(胚前期): before 2 weeks • embryonic period(胚期): 3-8 weeks • fetal period(胎儿期): after 9 weeks
Fertilization(受精) • Definition: the process by which the male and female gametes(sperm and ovum) unite to give rise to zygote • site: in the ampullary region(壶腹部)of the oviduct
conditions: 1) maturation of oocyte 2) maturation of spermatozoa
3) capacitation(获能)and acrosome reaction(顶体反应)of spermatozoa • capacitation factor: secreted by epi. cells of oviduct, capacity • of releasing acrosome enzymes • 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 within 24 hrs
Processes of fertilization: • Phase I • Penetration of the corona radiata(放射冠), acrosomal release • Phase II • Penetration of the zona pellucide(透明带) • ZP with receptors – zona pellucida spongy – the release of local enzymes • Phase III • Entrance, formation of zygote
Entry – response • Cortical or zona reactions -Compaction - impermeable to more sperm • Oocyte finishes 2nd meiotic division • Female /Male pronucleus • Metabolic activationof the egg • Results of fertilization • Diploid • Genetic sex • Cleavage
Cleavage (卵裂) • Mitosis • Two cell stage (30h) • Morula(桑椹胚) (72h) • inner cell mass • embryoblast • outer cell rim • trophoblasts • Blastocyst (胚泡)(5d) • Blastocoele • The cells of morula secrete fluid • Zona pellucide disappears
Blastocyst (胚泡) trophoblasts (滋养层) • blastocoele (胚泡腔) inner cell mass (内细胞群)
Uterus at Time of Implantation • Puberty – menstruation (28 days) • Hormonal regulation • GnRH • FSH • LH • Granulosa/theca cells • Estrogens • Progesterones • The endometrium of the uterus is • in the secretory phase
Implantation(植入) • -Passage through the uterine tube • Day 5 –Day 11 Uterus • Orientation of implantation • Location - ant or post, fundus • Trophoblasts overlying the embryoblast pole attach to the endometrium and begin to invade.
Processes • zona pellucide disappear → polar trophoblast touch the endometrium→secrete enzymes →dissolve the endometrium → embedded into endometrium → coagulation plug seal the space
Implantation site • Normal:ant or post wall of the uterus, fundus • Abnormal: • Internal os of the cervix (placenta previa) • Ovarian • Abdominal • Tubal(most common) Ectopic pregnancy (宫外孕)
endometrium →decidua: • -decidua basalis (底蜕膜) • -decidua capsularis(包蜕膜) • -decidua parietalis(壁蜕膜) • conditions: • -endometrium is in secretory phase • -morula reach the cavity of uterus on time • -zona pellucide disappears in time
Invitro fertilisation • 体外受精联合胚胎移植技术(IVF):又称试管婴儿,是指分别将卵子与精子取出后,置于试管内使其受精,再将胚胎前体---受精卵移植回母体子宫内发育成胎儿的过程。 Preimplantation Genetic Diagnosis • 植入前遗传学诊断(PGD) • 从发育到4-8细胞的胚胎中,取出一个细胞进行细胞遗传学或分子遗传学检查,再将检查结果正常的胚胎放入子宫内,以达到优生优育目的。 • 目前主要用于已知患有遗传性疾患夫妇或高风 险遗传疾患携带者(如高龄妇女)。
Bilaminar Germ Disc (二胚层胚盘) (Second week of development) • Implantation - sinks deeper • The outer cell layer • Trophoblasts • Cytotrophoblasts • 细胞滋养层 • Syncytiotrophoblasts • 合体滋养层 • Inner cell mass (embryoblast) • Fluid collection – amnion • Epiblasts & hypoblasts
Week two – Day 9-12 • Implantation • Covered the endometrium- fibrin plug • Complete – slight bulge • Trophoblasts • Vacuoles within syncytiotrophoblasts- fuse and form lacunar networks • Uteroplacental circ • Extra-Embryonic Mesoderm • btwn troph & cavity • Somatic/splanchnic
Week 2 – Day 13-14 • Trophoblasts • Primary villi • Yolk sac • Primary to seconday • Chorionic plate • Connecting stalk
The Bilaminar Embryo • Disc btwn • Amnion(羊膜腔) • Yolk sac(卵黄囊) • Bilaminar disc • Epiblasts(上胚层) • Hypoblasts(下胚层)
End of the Week of Twos • 2 major cell masses • Trophoblasts • Inner cell mass • Trophoblasts • Cytotrophoblasts • Syncytiotrophoblasts • Embryonic Cavities • Amniotic cavity • Yolk sac • Germ Disc • Epiblasts • Hypoblasts