A cytochemical study of ribonucleic acid distribution in the spermatogenic cells of Drosophila virilis.

The primary spermatocytes of Drosophila virilis have been shown to undergo an approximate 300-fold increase in volume and to possess an abundance of ribo somes in the cytoplasm (Ito 1960). These ribosomes are probably involved in the biosynthesis of the various materials needed for this tremendous volumetric increase. Olivieri and Olivieri (1965) have demonstrated that RNA synthesis occurs in sper matogonia and spermatocytes of D. melanogaster but that no post-meiotic synthesis of RNA occurs. Thus, any RNA present in the spermatids must have been synthe sized earlier in the spermatogenic cycle and retained in the cytoplasm. Using pyronin to demonstrate RNA, Daoust and Clermont (1955) reported a gradual in crease in cytoplasmic RNA in the early primary spermatocytes of the rat. This was followed by a decrease in RNA in the late primary spermatocyte stages, secon dary spermatocytes, and spermatids. This study was undertaken to describe the distribution of RNA in the germ cells of D. virilis during the spermatogenic cycle.