EXPRESSION OF PROTAMINE P2 IN THE TESTIS OF THE COMMON MARMOSET AND MAN VISUALIZED USING NONRADIOACTIVE IN-SITU HYBRIDIZATION

Information on the organization of the spermatogenic cycle of the comm on marmoset (Callithrix jacchus), a small New World primate, is limite d to a single histological report on the differentiation of spermatids . In the present study we have used non-radioactive in-situ hybridizat ion with a cRNA probe directed against marmoset protamine 2, on fixed sections of marmoset and human testis to elucidate the organization of mature germ cells within the seminiferous epithelium. Specificity of the probe was checked on Northern blots; mP2 hybridized exclusively to mRNA in samples extracted from marmoset and human testis. In sections from human and marmoset testis, positive staining for mRNA was confin ed to round and elongating spermatids and in the human was reduced in samples from patients with incomplete spermatogenesis. In the human, P 2 mRNA was present in groups of cells consistent with the presence of more than one stage of the spermatogenic cycle in transverse sections of individual tubules. In the marmoset, P2-positive cells were detecte d as a continuous ring of staining in the majority of sections of tubu les whilst in others only a group(s) of cells was positive. We conclud e that the arrangement of the spermatogenic wave in this New World pri mate may be intermediate between that seen in rodents (segmental) and in the human (helical).