Early mammalian embryology Flashcards
What is the yolk and cleavage type?
Rotational holoblastic cleavage, isolecithal yolk
Define a morula
a solid ball of cells resulting from division of a fertilized ovum, and from which a blastula is formed.
In what portion of fertilization canal does the zygote undergo its first division?
In the ampula
What two types of cells appear at the 16 cell stage?
Trophoblast cells and ICM cells (Embryonic Stem Cells)
A note about polarity.
A variety of factors may need to be on one side in order to repress some factors and what not.
Define asymmetry
an uneven distribution of organelles, molecules, or functions within individual cells of the same type
Define polarity
a situation where the asymmetrically distributed entities have an invariable, noninterchangeable and irreplaceable position in all cells of the same type
Can the direction that a cell is divided cause assymetry?
yes. Just keep this in mind
Polarization of factors leads to…
…different determinants in progeny cells
Go over the videos! there will be questions
You can’t tell me what to do. But its good advice..
What are the first types of cells to flow through the primitive groove?
endoderm cells
What types of cells does the endoderm coming through the primitive groove push out?
hypoblast
What is the second kind of cell that comes through the primitive groove?
mesoderm
What is the fetal portion of the placenta called?
chorion
What is the maternal portion of the placenta called?
decidual cells
What are antagonists?
Factors that inhibit another factor
What are Wnt and BMP
patterning and cell progression signals that activate hox genes
Define hox genes
Hox genes are a group of related genes that control the body plan of an embryo along the head-tail axis.
If hox #4 is knocked out, will the area have charactersitics of #5 or #3?
3
There are three possibilities in twinning. what are they?
- two chorions, two aminions
- one chorion, two amnions
- one chorion, one amnion
Define chimera
a single organism composed of cells from different zygotes.
Define paralogue
pair of genes derived from the same ancestral gene
Define orthologue
Genes in different species that have a dubious ancestral gene they are both from
