Figure 1.

Morphology and chromosomal constitution of a normal spermatogonium, primary spermatocyte, or round spermatid. The three types of spermatogenic cells that were identified under a differential interference microscope were: A, their chromosome complements formed in the mouse oocytes; B, fluorescent signals of X and Y; and C, 18 chromosomes by fluorescent in situ hybridization analysis