Embryology Flashcards
(12 cards)
When does the egg/conceptus take place?
Fertilisation to end of 3rd week
When does embryo take place?
Beginning of 4th week to end of 8th week
When does fetus formation take place?
3rd month to birth
What is step 1: Ovulation?
Secondary oocyte is released from the ovary and swept into the oviduct
What is step 2: Fertilisation?
Single sperm penetrates the secondary oocyte. Eventually, the sperm and eff nuclei fuse resulting in a zygote
What is step 3: cleavage?
Zygote soon undergoes rapid mitotic cell divisions as it moves along the oviduct toward the uterus, becoming a pre-embryo that consists of two cells then 4 then 8
What is step 4: Morula?
By day 4, successive divisions produce a morula, a sollid ball of cells that enters the uterus
What is step 5: blastocyst?
The pre-embryo becoomesa blastocyst, a hollow ball of cells with a fluid filled cavity. Blastocyst has freed itself from the zona pellucida and can increase in size.
What is step 6: Implantation?
Blastocyst attaches to the uterine lining (endometrium) and begins to digest its way inward. The ells of inner cell mass begin to form primary germ laters
The blastocyst has what 2 types of cells? When does it implant into uterine wall?
Inner cell mass and the outer epithelial layer (trophoblast).
Between 5 to 10 days, blastocyst implants into uterine wall
Gastrulation is what?
Formation of primitive streak which defines all major body axes.
what are the3 germ layers
Ectoderm, Mesoderm, Endoderm.
