CMMB 403 Lecture Notes - Lecture 4: Cytoskeleton, Interphase, Gastrulation

• School: University of Calgary
• Department: Cellular, Molecular and Microbial Biology
• Course: CMMB 403
• Professor: John Cobb

Document Summary

Cells developed autonomously, and only make one type of cell. Cells separated from blastula do not go on to form embryos, they remain the cells they were destined to be. Driesch"s demonstration of conditional (regulative) specification in sea. First experimental demonstration of regulative development (another term for conditional specification) Thus, these cells were not yet determined to become a particular part of the embryo. An intact 4-cell sea urchin embryo generates a normal larva. When you remove the 4-cell embryo from its fertilization envelope and isolate each of the four cells, each cell can form a smaller, but normal larva. Note that the four larva derived in this way are not identical, despite their ability to generate all the necessary cell types. Conditional specification outcome: separated blastomeres become entirely new embryos because at this stage, cells are still not determined yet, and thus can re-write their fates according to the signals a cell gets from surrounding cells.