Although many validated techniques for oocyte maturation in vitro have been developed and eggs with normal development competence can be produced by these methods, the mechnism triggering oocyte maturation in vivo is still poorly understood. Little doubt exists that meiosis is reinitiated in pre-ovlulatory follicles by peak levels of gonadotrophins and that follicle somatic cells are directly involved since no receptors for gonadotrophins have been found on the oolemma.