Metamorphosis: an exquisite model for hormonal regulation of post-embryonic development.

Division of Developmental Biochemistry, National Institute for Medical Research, London, U.K.

Biochemical Society symposium 1996

Metamorphosis in invertebrates and vertebrates, a process highly conserved throughout evolution, is an ideal model for studying mechanisms of post-embryonic development regulated by external signals. Amphibian metamorphosis also shares many similarities with mammalian development in the perinatal period. The precocious induction in vivo and in culture of insect and amphibian metamorphosis by exogenous thyroid hormones, and its retardation or inhibition by prolactin (PRL), have allowed the analysis of such characteristic features of post-embryonic development as morphogenesis, tissue remodelling, gene reprogramming, and programmed cell death. Recent studies on metamorphosis have revealed the important role played by such processes as auto-and cross-regulation of thyroid hormone receptor (TR) genes and by cell death or apoptosis, as in the maturation of the central nervous system, tissue restructuring and organolysis.