Question

When and how does an autonomous specification of cell fate happen?

Answer 1

Autonomous specification of cell fate - occurs during embryonic development (mostly in invertebrates). Happens when a embryonic cell is differentiated to perform a specialized function with out any external cues or signals. This cell differentiation and specialisation is carried out by cytoplasmic determinants or factors formed in ovum during oogenesis. Most of these are maternal RNAs which carry information for cell specialisation. These cytoplasmic determinants are distribtued asymmetrically at various locations in the ovum, such that when the zygote (fertilized ovum) divides these determinants are unequally divided among the resulting daughter cells. Since these cells now have different amounts of materal regulatory factors or determinants in them they will differentiate into specific cell type.