Origin of cranial placodes from a common primordium

Schlosser, Gerhard. (2021). Origin of cranial placodes from a common primordium. In Gerhard Schlosser, Development of sensory and neurosecretory cell types: Vertebrate cranial placodes, Volume 1. Boca Raton: CRC Press.

Abstract

Chapter 3 shows that, in spite of the distinct derivatives and functions of different placodes, all cranial placodes have a common origin in embryonic development. The chapter first highlights some important similarities between the development of different placodes, viz. the generation of neurons or sensory cells by most placodes and the importance of cell shape changes and morphogenetic movements during placode development. It then argues that these shared aspects of placode development are due to the origin of all placodes from a common primordium, the so-called pre-placodal ectoderm (PPE). The PPE is characterized by the expression of Six1/2 and Six4/5 transcription factors and their cofactors of the Eya family. The second part of the chapter reviews how the PPE originates in early vertebrate development in parallel to other ectodermal territories such as neural crest, neural plate and epidermis. This review focusses in particular on the role of transcription factors during this process (including the increasingly dorsally restricted TFAP2a, Msx1, Dlx3/5, Ventx2, an FoxI1-4, and the increasingly ventrally restricted Sox3, Sox11, Zic1/3, and Geminin), since these appear to play central roles for the cell fate decisions that step by step convert pluripotent cells into sensory and neurosecretory cell types.

Publisher

CRC Press

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Attribution-NonCommercial-NoDerivatives 4.0 International

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Zoology (Book Chapters)