HAPLOID TRANSCRIPTS PERSIST IN MATURE HUMAN SPERMATOZOA

Mammalian spermiogenesis is marked by the morphological and functional differentiation of round haploid spermatids into mature spermatozoa. A molecular restructuring of the chromatin accompanies this process fa cilitated by the transition proteins and protamines which compact and condense the genetic material within the developing spermatid. Previou s studies from this laboratory have demonstrated that human protamines PRM1, PRM2 and transition protein TNP2 transcripts are associated wit h round and elongating spermatids. Extending this investigation, we ex amined the occurrence of these transcripts in mature spermatozoa by in -situ hybridization analysis using [S-35]-labelled cRNA probes. These results demonstrate that PRM1, PRM2 and TNP2 haploid-specific transcri pts are present in mature spermatozoa. Quantitative analysis of the lo calized signal also indicates that the PRM1, PRM2 and TNP2 transcripts persist at a similar ratio to that previously described for these tra nscripts in human testes, i.e. PRM2>PRM1 approximate to TNP2. The pers istence of these transcripts in mature spermatozoa warrants further in vestigation.