Figure 2

Flow cytometric DNA content analysis of rodent testicular cell suspensions. Cell suspensions were prepared from adult rats (a), mice (b), guinea pigs (c), and from 21-day-old rat pups (d), and stained with the vital dye Hoechst 33342. Three main subpopulations of cells can be easily distinguished in the histograms obtained for adults of the three species (a, b, c), according to their DNA content (C, 2C, and 4C). The additional peak to the left of the C subpopulation corresponds to elongating spermatids and elongated condensed spermatozoa, as previously reported [9]. The immature nature of the 21-day-old rat testis (d) is evident, since the C subpopulation is absent.