Coding 13 Flashcards
Where does the egg in a chick undergo its first cleavage?
While it is in the hen
Where is the chick fertilized before the albumin and the shell are secreted to cover it?
The oviduct
What is the blastodisc?
A small disc of yolk free cytoplasm that sits on top of a large mass of yolky cytoplasm
When does MZT happen?
128 cell stage
In chicks what are the 3 steps of gastrulation?
- Formation of the lower hypoblast and the upper epiblast
- The epiblast makes the primary body structure, head, and neck
- Secondary body formation from the lower abdomen and tail
What is the koller’s sickle?
The posterior end of the area pellucida where the cells thicken and make the anterior-posterior region
What is the hypoblast?
The cells that lead the gut formation and the yolk sac
What part of the egg undergoes cleavage?
The blastodisc in the animal pole
What is the epiblast?
Cells that make the germ layer and the extraembryonic membrane
What is the posterior marginal zone?
A beltlike region between the area opaca and the koller’s sickle
How is the blastocoel cavity made?
By the epiblast and the hypoblast joining at the PMZ
How is the primitive streak made?
The clockwise and counterclockwise motion of thousands of epiblast cells
What is the primitive groove?
Cells that converge at the primitive streak and form a depression
What is the hensen’s node?
The anterior end of the primitive streak
How does the primitive streak play a role in body axes?
When cells ingress through the streak somite formation occurs
What is the PMZ analogous to?
The nieukwoop centre
How is PMZ similar to NC?
It secretes Vg1 (nodal protein) and it is localized to the side due to BMP4 inhibition and nodal proteins are needed for primitive streak formation
What happens once the primitive streak has completed its formation?
It secretes cerebrus to repress its own nodal proteins and formation
When is germ layer identity established?
Before gastrulation
What do the first cells that ingress through the hensen’s node make?
Pharyngeal endoderm
What do the second cells that ingress through the hensen’s node make?
Presumptive foregut endodermal cells
What do the third cells that ingress through the hensen’s node make?
Choramesoderm cells
What is the mammalian oocyte wrapped in?
Cumulus cells
What takes the oocyte from the ovary to the oviduct?
Fimbirae
Where does fertilization occur?
Near the ovary in the ampulla
What does the first cleavage depend on?
The location of sperm entry
What is compaction?
When adhering proteins such as E-cadherins are expressed and the blatomeres cluster into a ball
When does compaction occur?
In the third cleavage
At the 16-cell stage there is a division into internal and external cells that form?
The internal makes the ICM
The external makes the trophoblast
What are the inner cell mass cells?
Pluripotent embryonic cells