MCD BIO 138 Lecture Notes - Lecture 2: Embryonic Stem Cell, Blastomere, Spermatogonium
4 Jun 2019
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Lec 2 gametes & stem cells: oogenesis = formation of oocytes/eggs, spermatogenesis = formation of sperm, gametes arise from germ cells. Arise early in development & set aside. Want to set them aside & maintain their plural-potency; protect them from external signals origin of germ cells: germ cells set aside in early development stages true for flies, nematode, frogs. Germ cells inherit cytoplasmic determinants already present in fertilized egg (????????) cytoplasmic determinants: materials e. g. rna, protein present in egg"s cytoplasm. Can be asymmetrically localized in cell; after divides: one daughter cell inherits more than the other: p granules: stuff (tf, etc) that keep cells in undifferentiated states; Uniformly distributed in egg before fertilization; aggregates at one side of cell after fertilization fertilization triggers cytoskeletal rearrangement. Eventually all p granules end up in a single cell, which forms gametes. Stem cell: cell divides throughout life of organism, making more cells like itself and providing precursor cells for a pathway of differentiation.
