Fertilization and Gastrulation Flashcards
What allows sperm to pass through the corona radiata?
hyaluronidase
mucosal proteins
mvmt of tail
What stage of development is only present during week 2?
hypoblast
What is the corona radiata?
layer of follicular cells from mom that surround the oocyte; the most superficial layer of ovum
What does primitive blood come from and where is it formed?
from extraembryonic splanchnic mesoderm
forms in wall of yolk sac
What is the prechordal plate?
part of hypoblast that eventually becomes the mouth and organizational center for the head
What are the basic steps of egg penetration?
capacitation
passage of sperm through corona radiata
penetration of zona pellucida
Where is the mitochondrial sheath on a sperm?
on middle piece of tail
What forms the male pronucleus?
What degrades from sperm?
cytoplasmic contents form pronucleus
tail and mitochondria degrade (mito dna only from mom)
In the obstetrical/gestational view, when does the calendar start?
Last menstrual period
What happens to the primary yolk sac?
splits into 2: secondary goes up against epiblast primary goes to opposite side (remnant of primary umbilical vesicle?)
What is the chorion?
3 layers:
extraembryonic somatic mesoderm
cytotrophoblast
syncytiotrophoblast
= one of the layers of placenta
What are the 3 parts of the sperm tail?
middle piece (with mitochondrial sheath)
principal piece
end piece
What is the extraembryonic somatic mesoderm?
cells that line the trophoblast and cover the amnion
produces the connecting stalk and chorion
What happens in week 1 of gestation?
Fertilization Cleavage Blastocyst Inner cell mass Implantation
What can hydatidiform moles turn into?
What percentage of them do this?
choriocarcinomas = malignant tumor
3-5%
When does the acrosomal reaction occur?
when the sperm touches the zona pellucida
What is a complete mole from?
fertilization of empty oocyte –> duplication of sperm
or: fertilization of empty oocyte by 2 sperm
What is the trophoblast? When does it occur?
Cells surrounding inner cell mass
day 5 –> degrades day 7
When does cleavage occur?
~30 hours after fertilization
What is the zona pellucida
meshwork of glycoproteins that surround the oocyte; just deep of corona radiata
What is the bilaminar disc and when does it form?
2 discs are of epiblast and primary yolk sac formed of hypoblast
forms in week 2
When is implantation?
day 6
What is a blastomere?
One of first few cells after fertilization
what are the 2 types of extraembryonic mesoderm?
somatic and splanchnic
What is the extraembryonic splanchnic mesoderm?
cells that line the yolk sac
produce primitive blood
What is a hydatidiform mole?
benign, giant thing of trophoblast that causes excessive amounts of hCG
can be partial or complete
Where do choriocarcinomas have a high likelihood to spread to? (6)
vagina lungs bone brain liver intestines
What is the very basic structure of a sperm?
head
neck
tail
What does the trophoblast differentiate into?
cytotrophoblast
syncytiotrophoblast
What is placenta previa?
When placenta implants over cervical os
can be marginal, partial, or total