Early embryonic development Flashcards
When and where does fertilisation occur?
in the ampulla of the uterine tube within 12 hours of ovulation
What is capacitation?
maturation of sperm
What happens in fertilisation?
the diploid number of chromosomes (46) is restored in the sperm and ovum (from haploid - 23)
When is the initiation of cleavage?
within 36 hours of fertilisation
What is cleavage?
repeated mitotic division of a zygote into blastomeres that cluster into a compact mass called a morula
What is compaction?
when the central cells are linked by gap junctions
What is the structure of a morula?
solid ball of 16+ cells with inner and outer layers
Until when are cells totipotent?
up to the blastocyst stage
When should cells be removed for genetic testing?
at 5-6 days
What happens at 5.5-6 days?
binding to the uterus epithelium occurs
What happens at 6-7 days?
implantations of blastocyst begins
What happens on the 8th day?
- trophoblast divides
- two layers form in the embryo
- the amniotic cavity begins to form
What happens on the 9th day?
amniotic cavity has formed
What happens at 11-12 days?
embryonic disc has formed with two layers bilayered
What happens at the end of week 2?
- 2 layers develop in the trophoblast
- 2 layers develop in the inner cell mass
- 2 cavities form
What is preeclampsia?
maternal hypertension and proteinuria
What is the most common site of ectopic implantation?
the ampulla
What are congenital malformations?
conditions that are present at birth
How are axes determined in the embryo?
- dorsal and ventral are determined in the oocyte
- left and right are determined by cilia movement in the node
