Acquisition of Competence to Enter Meiotic Metaphase During Mammalian Spermatogenesis

Abstract

Little is known about factors that control the exit of the spermatocyte from meiosis I prophase to metaphase I (the G₂/M transition). Before negotiating this critical cell-cycle transition, the spermatocyte must acquire competence to condense and segregate homologous chromosomes and must receive the appropriate signal(s) for entry into metaphase; these two requirements do not necessarily coincide temporally. The work of Wolgemuth and co-workers (see Chapter 6, this volume, for review) has provided ample evidence that a number of important and highly conserved cell-cycle proteins are in the right place at the right time, but it is not known how these proteins relate in either a mechanistic or regulatory sense to acquisition of meiotic competence and the G₂/M cell-cycle transition in spermatocytes.