Morphogenetic action of retinoids and estrogens

Retinoids and estrogens are small lipophilic compounds fulfilling important biological roles in vertebrate development, reproduction and homeostasis. Both types of ligands are regulators of gene transcription by binding to (n uclear) proteins acting as ligand-activatable transcription factors, member s of the nuclear receptor gene superfamily. Retinoids and their multiple re ceptors (RARs/RXRs) are particularly well-known for their role in early dev elopment and spermatogenesis, while much less is known about the two estrog en receptors (ER alpha/beta) during development. In this article we describ e some of our previous and present work in both areas of research.