In situ localization of mRNAs coding for mouse testicular structural genes.

In situ hybridization histochemistry has been used to localize mRNA transcripts of five nuclear and cytoplasmic structural genes in the mouse testis. The mRNAs for three nuclear structural proteins involved in chromatin transformation during spermatogenesis (the two protamine variants of the mouse and one of the testis-specific proteins) are restricted solely to postmeiotic germ cells. In contrast, mRNAs for two other structural proteins, actin and alpha tubulin, are detected throughout spermatogenesis. Although present in premeiotic, meiotic, and postmeiotic cell types, the mRNA levels of actin and alpha tubulin differ considerably during spermiogenesis, the haploid phase of spermatogenesis. Actin mRNA levels decrease markedly as the male gamete differentiates during spermiogenesis whereas alpha-tubulin mRNAs are equally abundant in the haploid round and elongating spermatids.