BIOL303 Lecture Notes - Lecture 5: Polarity In Embryogenesis, Blastomere, Mesenchymal Stem Cell
5 Dec 2016
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Mitosis in early development: stripped down cell cycle, m and s phase only (cyclin degredation). No increase in cell mass, constant cytoplasmic volume. Rapid, synchronous cell divisions running off of maternal transcripts. Mitosis is late development: regular cell cycle with normal s, g and m phases. Mid blastula transition: the transition from early, rapid, bi-phasic mitoses to an embryo stage of mitoses: mitoses includes gap phases 2. loss of synchronicity of divisions 3. transition to zygotic mrna. Protostome: type of development where the blastopore becomes the mouth. Deutersotome: type of development where the blastopore becomes the anus. Diploblastic: organisms that develop 2 germ layers - lack a true mesoderm. Triplobalstic: organisms that develop 3 germ layers - endoderm, mesoderm and ectoderm. Holoblastic cleavage: entire blastomere divides evenly into smaller cells. Isolecithal: eggs have little yolk and it is evenly distributed. (radial, spiral, bilateral or rotational divisions)
