Proliferative activity of the developing seminiferous epithelium during prespermatogenesis in the golden hamster testis measured by bromodeoxyuridine labeling

Abstract

Bromodeoxyuridine (BrdU)-labeling was used to study the cell kinetics of the developing seminiferous epithelium in the testes of golden hamsters aged 10.5 to 27.5 days post conception (dpc), i.e., during a period beginning one developmental day before testicular differentiation (11.5 dpc) and extending to the appearance of the first "mature" spermatogonia. Supporting (Sertoli) cells continuously proliferate throughout the period studied. Labeling indices amount to about 30% between the 10.5th and 16.5th dpc, and subsequently decrease to levels below 10% on the 26.5th and 27.5th dpc. Germ cells (prespermatogonia) proliferate between the 10.5th and 15.5th dpc and again, after a period of mitotic quiescence, from the 24.5th dpc onwards. This pattern of prespermatogonial proliferation substantiates and further specifies the successive appearance of M-prespermatogonia (10.5th to 15.5th dpc: proliferating), T1-prespermatogonia (16.5th to 23.5th dpc: quiescent), and T2-prespermatogonia (24.5th to 27.5th dpc: proliferating). Thus, the M-prespermatogonial phase of germ cell proliferation is shown to commence at least 24 h before testicular differentiation. Transitions from M- to T1-phase and from T1- to T2-phase are rather abrupt. Both the latter observation and the comparison with oogonial development in the female at the corresponding time (onset of meiosis) indicate the presence of an underlying control mechanism operative during prespermatogenic development. Due to different nuclear staining patterns, the BrdU-labeling method allows temporal subdivision of the S-phase, thus opening up prospects of more detailed cell-kinetic analyses of the seminiferous epithelium.

Mitoses of existing corticotrophs contribute to their proliferation in the rat pituitary during the late fetal period

“…Therefore, we used a dose of 50 mg/kg for the double administration of BrdU in this study. These results are essentially in accordance with those presented by Ikeda and Yoshimoto (1991), Miething (1993), and Carbajo et al (1995, although there is some discrepancy due to the experimental conditions employed.…”

Prespermatogenesis and spermatogoniogenesis in the bovine testis

“…Relatively large prespermatogonia, found mostly as single cells in the center of the testicular tubules, are the bovine equivalent to the resting T 1 -prospermatogonia described in rodents (B Hilscher et al 1972(B Hilscher et al , 1974Miething 1993). Different, however, from the pattern reported for the rat and golden hamster, and probably due to the long time span of their occurrence (from day 80 p.c.…”

“…As in the rat and golden hamster (B Hilscher et al 1972(B Hilscher et al , 1974W Hilscher and B Hilscher 1976;Miething 1993Miething , 1998, the bovine male germ cell population also shows periods of different proliferative activity in the time span between testicular cord formation in the embryo and the onset of spermatogenesis in the pubertal animal. A period of high proliferation rate is observed from day 50 p.c.…”

“…In a number of small rodents the prepubertal germ cells undergo clear-cut phases of proliferation or mitotic quiescence (B Hilscher et al 1972(B Hilscher et al , 1974W Hilscher and B Hilscher 1976;W Hilscher 1991;Miething 1993Miething , 1998: Two waves of enhanced proliferation (M-and T 2 -prospermatogonia) are described which are separated by a generation of non-proliferating cells (T 1 -prospermatogonia). This scheme of prespermatogenesis, found in the rat and golden hamster, could not be corroborated by studies of the human prenatal testis.…”

Effects of thymulin on in vitro incorporation of 3H-thymidine into gonocytes of newborn rat testes

“…Moreover, thymulin is efficient at the beginning of the postnatal period, in addition to its capacity for stimulating in vitro proliferation of germ cells in fetal ovaries and testes, as revealed by previous work (Pr6pin, 1991; (Beaumont and Mandl, 1963). In contrast, it is intriguing to observe 3 H-thymidine incorporation into 45% of germ cells, even without thymulin, between days 4 and 7, whereas about 70% of germ cells disappear during that same period (Beaumont and Mandl, 1963;Franchi and Mandl, 1964;Huckins and Clermont, 1968 (Franchi and Mandl, 1964) or only on day 7 (Huckins and Clermont, 1968 (Miething, 1993). Moreover, a recent study described prenatal germ-cell death occurring in the mouse as being apoptotic in nature based on flow cytometric and fluorescence microscopic investigations (Coucouvanis et al, 1993 (Rossi et al, 1993), which is involved in germ-cell proliferation.…”