THE RÔLE OF CUMULUS CELLS AND SERUM IN MOUSE OOCYTE MATURATION <i>IN VITRO</i>

Abstract

Summary. Mouse oocytes were matured in vitro with or without cumulus cells and in medium containing non-dialysable or dialysable serum fractions. The criterion for successful maturation of the oocytes was the formation of two-cell embryos after fertilization in vitro. The data demonstrated that (1) cumulus cells do not improve oocyte maturation and subsequent fertilization in vitro and (2) the large molecular weight fraction of serum is the critical component of the system involving maturation in vitro.