Embryology Flashcards
The first stage in the development of a fetus
fertilisation the process by which the male sperm and female egg join together.
Approximately _______ hours after fertilizations, the fertilized oocyte (egg) splits into two cells of equal size; called _________.
thirty; blastomeres
After three more divisions, there are 16 cells. At this point, the group of cells is referred to as the ______.
morula
Within the first week, the cells of the morula reorganize to form a cavity, known as the ______.
blastocyst cavity (blastocoel).
the blastocyst is comprised of two different cell types:
Outer cell mass (trophoblast) Inner cell mass (embryoblast)
contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta
Outer cell mass (trophoblast)
responsible for the formation of the embryo itself
Inner cell mass (embryoblast)
The trophoblast divides into the _______ and ______
syncytiotrophoblast and cytotrophoblast.
The embryoblast divides into the ______ and ______.
epiblast and hypoblast , forming a two-layered structure; the bilaminar disk.
The amniotic cavity forms within
the epiblast
Initial Cellular Divisions
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After the initial rounds of cellular divisions, the embryo must implant into the __________
endometrium of the uterus
During this process, the syncytiotrophoblast becomes continuous with the uterus – such that maternal blood vessels (known as sinusoids) invade the spaces within the syncytiotrophoblast (known as lacunae).
Implantation
In___________, implantation of the embryo occurs in the lower uterine segment (instead of in the normal position of the upper posterior uterine wall).
placenta praevia
A low-lying placenta is more susceptible to
haemorrhage