Abstract
Cells were labeled by intratesticular injection of [35S]methionine. After 14-16 h the relative rates of incorporation of label in spermatocytes, early spermatids and late spermatids were 10:2:1 respectively. Approximately 15% of the soluble (100,000 g supernatant) and 20% of the particulate proteins solubilized by NP-40 (from the 100 000 g pellet) that were detectable on 2-dimensional gels showed stage-specific synthesis. A large number of proteins were detectable only in post-meiotic cells and may be valuable for studying the control of gene expression in haploid cells.