BACKGROUND Companion studies using an experimental non-human primate paradigm known as a testicular clamp indicated that the behavior of undifferentiated type A spermatogonia did not conform fully to earlier classical models. This issue was therefore re-examined in normal monkeys. METHODS Adult male rhesus monkeys (n = 4) received an i.v. bolus of 5-bromo-2'-deoxyuridine (BrdU): one testis (f...

The purpose of the present study was to determine whether dark and pale type A spermatogonia (Ad and Ap, respectively) are mitotically active during prepubertal development and whether proliferation of these germ cells during this protracted phase of primate development occurs predominantly during infancy before gonadotropin secretion is arrested. Four neonate (1-2 days of age), four infant (4-...

The present study examines the existence of clonogenic patterns in the proliferation and differentiation of spermatogonial stem cells in two species of non-human primates, the marmoset and the rhesus monkey. We developed a novel approach to detect proliferating spermatogonial clones in whole mounts of seminiferous tubules. Dual fluorescence labeling of bromodeoxyuridine and acrosin in conjuncti...

The transition from mitosis to meiosis is unique to germ cells. In murine embryonic ovaries and juvenile testes, retinoic acid (RA) induces meiosis via the stimulated by retinoic acid gene 8 (Stra8), but its molecular pathway requires elucidation. We present genetic evidence in vivo and in vitro that neuregulins (NRGs) are essential for the proliferation of spermatogonia and the initiation of m...

Mice conceived 6 weeks after paternal exposure to ionizing radiation were fathered by sperm that were Type B spermatogonia at the time of irradiation. Previous studies of these offspring showed that this paternal F0 germ cell irradiation led to decreased embryonic cell proliferation rates, altered enzyme activities, protein levels and whole-body weights. In the present study, we examined four g...

Male rabbits, aged 4.5 months, were subjected to graded total gamma irradiations of 0.5 Gy, 1.5 Gy, 2.5 Gy and 3.0 Gy with a dose density of 24 Gy/min. The genetic effects in spermatogonia were assessed 3 months later using cytogenetic analysis of chromosomal preparations. The data showed a dose-dependent increase in the frequency of reciprocal translocations, induced in spermatogonia and detec...

The temporal expression of cell surface antigens during mammalian spermatogenesis has been investigated using isolated populations of mouse germ cells. Spermatogenic cells at advanced stages of differentiation, including pachytene primary spermatocytes, round spermatids, and residual bodies of Regaud and mature spermatozoa, contain common antigenic membrane components which are not detected bef...