Spermatids as male gametes.

Intracytoplasmic sperm injection (ICSI) is becoming increasingly popular in human infertility clinics as an efficient method for the treatment of male infertility. It is proposed that spermatids can be used as substitutes for spermatozoa if men are unable to produce sperm in their testes. At least in the hamster and mouse, the nuclei of round spermatids were capable of participating in syngamy when incorporated into homologous mature oocytes either by microsurgical ICSI or electrofusion. Normal mouse offspring were born after after electrofusion of oocytes with round spermatids. When culture in vitro of spermatogonia and spermatocytes is perfected, then spermatids, transforming spermatids and spermatozoa will all be able to be used as male gametes.