embryology Flashcards
1
Q
mosaicism
A
not all cells in embryo have same chromosomes
2
Q
gonocyte
A
name given to primordial germ cells when they are in the developing gonads
3
Q
which gene triggers male sex fetermination?
A
SRY gene - found only on Y chromosome
- triggers SOX9 transcription protein- which:
- inhibits development of ovaries
- contains genes to make testes
- instructs cells in genital ridge to become sertoli cells
4
Q
which protein regulates sex determination?
A
SOX9 protein - found in SRY gene
5
Q
stages of early embryogenesis
A
- day 2 - totipotency - 4 cells
- day 3 - pluripotency - 8 cells
- day 4 - compaction - morula forms
- day 5 - blastocyst forms
6
Q
what do embryonic stem cells develop from ?
A
embryoblast of blastocyst - they are pluripotent cells
7
Q
why do cells differentiate?
A
position in blastocyst
- eg. some trophoblast (outer) cells are in contact w/ embryoblast, some aren’t
- cells respond to local signals to develop + since their positions and signals are different, they become different
8
Q
prerequisite for implantation
A
hatching the blastocyst
- cells of blastocyst secrete proteases which break down zona pellucida - blastocyst escapes through digested zona
