More embryology Flashcards
Define pre-embryonic
A fertilized ovum up to 14 days old, before it becomes implanted in the uterus
Embryonic
- The fertilized egg of a vertebrate animal following cleavage before definite form arises. 3-8 weeks.
Fetal
In humans the fetal period extends from the first day of the ninth week of intrauterine life until birth. 9-38 weeks.
Discuss the changes taking place as the fertilised human ovum (zygote) travels down the Fallopian (uterine) tube to the uterus
- Oocyte is released from the ovary - Travels along the Fallopian (uterine) tube - Is fertilized by sperm in the ampulla - Fertilised oocyte is called the zygote - Ideal site for implantation is the posterior uterine wall
Zygote
A fertilised ovum/oocyte
Cleavage
The dividing of cells into two masses known as blastomeres. First cleavage happens ~30 hours after fertilisation (resting period)
Zona Pellucida
The glycoprotein ‘shell’ to prevent polyspermy
Morula
The result of cleavage of the fertilised oocyte, each cell is Totipotent
Ovary
The female reproductive organ producing oocytes/eggs for fertilisation
Fallopian tube
A tube the oocyte travels along to reach the uterus. The egg is fertilised at the ampulla of the fallopian tube.
Uterus
Female reproductive organ where implantation of the zygote and growth of the embryo occurs
Blastocyst
Formed from the compaction of cells that make up the morula
Trophoblast
(Outer cell mass) will later form support structures for the embryo (placenta)
Embryoblast
(Inner cell mass) will later become the bilaminar disk
Implantation
The attachment of the Blastocyst to the wall of the uterus at day 6 – 7