Blastocyst formation following intracytoplasmic injection of in-vitro derived spermatids into bovine oocytes.

Various types of male gametes, such as spermatozoa, spermatids and spermatids obtained after the in-vitro division of secondary spermatocytes, were injected into the in-vitro matured bovine oocytes in order to examine the possibility of utilizing in-vitro derived spermatids for intracytoplasmic injection. There were no significant differences in the development of bovine oocytes injected with various types of male gametes (cleavage rate, 31.0-37.8%; morula rate, 11.1-18.2%; blastocyst rate, 4.4-1.4%). Similarly, 22.0% of sham-injected oocytes (injection of medium plus polyvinylpyrrolidone) cleaved parthenogenetically but none of them developed to morula stage. There were no significant differences in embryo quality (assessed by cell number) of blastocysts obtained by the injections of various types of male gametes (124.0 +/- 9.6-152.5 +/- 15.5). This study demonstrates that various types of spermatogenic cells can be used for intracytoplasmic injection of oocytes to produce viable embryos.