Biochemical aspects of early differentiation in vertebrates.

Abstract

Publisher Summary This chapter reviews the information about changes in DNA, RNA, and protein during successive phases of embryonic development in vertebrates. It discusses cleavage and pregastrulation stages. Mammal embryos have been studied in toto until the blastocyst stage when two cell types can begin to be distinguishable based on their grouping and shape. In avian and reptilian embryos, little is known of the stages prior to primitive streak formation because the streak is the first visible landmark of differentiation. In contrast, in amphibians, much more is known of events during cleavage because there are visible differences between the cells such as the size, yolk content, and pigmentation that make them distinguishable for comparative studies. The chapter presents findings on amphibians; these findings have formed the basis of most of the recent thinking about differentiation in vertebrate embryos. Every developing tissue in vertebrate embryos depends to some extent on neighboring tissues for its normal differentiation. The chapter reviews recent work on neural induction and the interactions in the early embryonic axis.