ANAT 216 Lecture Notes - Lecture 21: Zona Pellucida, Primitive Streak, Amniotic Sac
28 Apr 2018
School
Department
Course
Professor
ANAT 216 week 8 lecture 1
Embryology
What?
Study of developmental events during prenatal
period
Pre-
embryonic
develop
Fert: sperm fuse w egg in ampulla of uterine
tube
Capacitation: initiated by oocyte signals,
removes cap of sperm made of glycoprotein
using hydrolytic enzymes in acrosome (break
down cement holding cells in corona radiate)
Sperm breaches corona radiate and zona
pellucida acrosomal rx so other sperm
cannot fert egg female and male pronuclei
form zygote (diploid)
Cleavage: blastomere cells in zygote divide, 1st
division w/n 24 hrs forming pre-embryo which
continue to divide
After 72 hrs morula forms w 16 cells, migrates
into uterine cavity, now has 100 cells
Blastocyst froms after 5 days, fluid filled hollow
sphere composed of layer of trophoblastic cells
and cluster of small round inner cell mass
(embryoblast), uterine milk penetrates zona
pellucida (breaks down and releases cells
inside- blastocyst) and rearranges cells of
blastomere to form fluid cavity (blastocoele)
Blastocyst: trophoblast cells= future placentra,
inner cell mass= future embryo
Implantation: in weeks 1-2, conceptus called
pre-embryo
Trophoblast adheres to and embeds into
endometrium, tropho divide into 2 layer
bilaminar disc (embryonic and blastodisc layer)
inner then splits into epiblast and hypoblast
layers adjacent ot embryonic cavity (amniotic
cavity formation)
Syncytiotrophoblast- multinuclear cytoplasmic
layer, cont to bury into wall of uterus
Embryonic
develop
(trilaminar
disc)
Gastrulation: 3rd week, embryonic disc
transforms into 3 germ layers
Primitive streak: narrow midline groove on
surface of epiblast, cells of epiblast pass thru
primitive streak creating inner endoderm,
middle mesoderm and outer epiblast become
ectoderm layer, mesodermal cells aggregate to
form notochord (1st axial support for 2mm
find more resources at oneclass.com
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Document Summary
Fert: sperm fuse w egg in ampulla of uterine tube. Capacitation: initiated by oocyte signals, removes cap of sperm made of glycoprotein using hydrolytic enzymes in acrosome (break down cement holding cells in corona radiate) Sperm breaches corona radiate and zona pellucida acrosomal rx so other sperm cannot fert egg female and male pronuclei form zygote (diploid) Cleavage: blastomere cells in zygote divide, 1st division w/n 24 hrs forming pre-embryo which continue to divide. After 72 hrs morula forms w 16 cells, migrates into uterine cavity, now has 100 cells. Blastocyst: trophoblast cells= future placentra, inner cell mass= future embryo. Trophoblast adheres to and embeds into endometrium, tropho divide into 2 layer bilaminar disc (embryonic and blastodisc layer) inner then splits into epiblast and hypoblast layers adjacent ot embryonic cavity (amniotic cavity formation) Syncytiotrophoblast- multinuclear cytoplasmic layer, cont to bury into wall of uterus. Gastrulation: 3rd week, embryonic disc transforms into 3 germ layers.
