Rattling the core of a well-established paradigm: is retinoic acid really necessary for meiosis entry?

Abstract

Independent studies from recent years have yielded a wealth of evidence supporting the model that retinoic acid (RA) triggers the expression of stimulated by retinoic acid 8 (Stra8) gene in germ cells thereby inducing their entry into meiosis (1, 2). Kumar et al.’s recent work published in 2011, however, boldly challenges this model, proposing that entry into meiosis, in fact, takes place independently of endogenous RA (3). This controversial claim has attracted intense interest in the field of developmental biology and has prompted several follow-up studies. one of these studies has proposed two homeobox genes, Msx1 and Msx2, to also be necessary for female meiosis initiation, and that their actions are likely mediated by the expression of Stra8 (4).