PATH 3000 Lecture Notes - Lecture 26: Inner Cell Mass, Germ Layer, Primordium
19 Apr 2020
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Path 3000 lecture 26 march 18, 2020 genetic and developmental diseases part i. Outline: normal embryonic development, developmental malformations, genetic factors, exogenous teratogens, chromosomal abnormalities, single-gene disorders. At a 16 cells stage, the embryo is known as the morula. This stage is interesting because the cells have not been programmed yet, meaning if one cell is taken away, this has no consequences for the embryo. In the blastocyst stage, there are about 70-100 cells with a lumen inside with an inner cell mass, which is what the embryo develops from. The cells on the outside of the ball of cells are trophoblast, which gives rise to the placenta. A cell taken away from the inner cell mass would have consequence for the development of the embryo because those cells are programmed. After the preimplantation and embryonic stage, which occurs from day 1 to day 6, gastrulation occurs, forming the germ layers: ectoderm, mesoderm, and endoderm.
