BIOL303 Lecture Notes - Lecture 5: Cyclin-Dependent Kinase, Spindle Apparatus, Polarity In Embryogenesis

• School: University of Waterloo
• Department: Biology
• Course: BIOL303
• Professor: Bruce Reed

Document Summary

Topic 5: mid-blastula transition the transition from the early rapid biphasic (only m and s phases) mitoses of the embryo to a stage characterized by: Mitoses that i(cid:374)(cid:272)lude the (cid:862)gap(cid:863) stages (cid:894)g(cid:1005) a(cid:374)d g(cid:1006)(cid:895) of the (cid:272)ell (cid:272)(cid:455)(cid:272)le. Vegetal pole=side where all the yolk is; yolky pole. Animal pole=side where more activity going on further from the yolk; low yolk pole: eggs having little yolk that is equally distributed are isolecithal and generally undergo holoblastic cleavage. In mammals and birds this type of meroblastic cleavage is called discoidal cleavage: eggs have much yolk in interior and are centrolecithal and display superficial cleavage. Much like the indentation of a rubber ball when poked. Inward movement of expanding outer layer so that it spreads over the internal surface of the remaining external cells. Migratio(cid:374) of i(cid:374)di(cid:448)idual (cid:272)ells fro(cid:373) surfa(cid:272)e i(cid:374)to e(cid:373)(cid:271)r(cid:455)o"s i(cid:374)terior. Individual cells become mesenchymal (separate from one another) and migrate independently.