Degeneration Of Spermatogenic Cells Research Articles

Comparative toxicities of dietary caffeine and theobromine in the rat

Caffeine, incorporated into pulverized Purina Rat Chow at a concentration of 0.5%, was fed to male Sprague-Dawley rats for 7 or 8 wk and the effects were compared with those of 0.8% dietary theobromine, fed to male rats for 7 wk. Both dietary methylated xanthines produced significant decreases in food consumption and body-weight gain when compared to their respective control groups. Food consumption of caffeine-fed rat was 57.2% of controls and for theobromine-fed rats it was 77.9% of the respective controls. Theobromine produced significant decreases in thymus weights, with caffeine producing smaller decreases. The theobromine-fed rats showed severe testicular atrophy with extensive spermatogenic cell degeneration and necrosis, while the testes of rats fed caffeine for 7 or 8 wk showed only scattered vacuolar degeneration of spermatogenic cells. Caffeine appears to be more potent than theobromine as an anorexic agent in rats, but to be equivalent to theobromine in its potential for inducing thymic atrophy and spermatogenic cell with testicular atrophy.

Dietary influences on theobromine-induced toxicity in rats

Theobromine-induced toxicity was compared at 8, 16, 21, and/or 28 days in rats given either a semisynthetic diet or a pulverized commercial diet in each of which 0.6 or 0.8% theobromine was incorporated. Rats given the pulverized commercial diet containing theobromine consumed more food and therefore, more theobromine over a 28-day period, and gained more weight than did rats given theobromine incorporated into the semisynthetic diet. Serum theobromine concentrations were significantly higher in rats given 0.8% theobromine in the semisynthetic diet than in rats given 0.8% theobromine in the pulverized commercial diet. Spermatogenic cell degeneration and necrosis in the testes of rats fed 0.8% theobromine in the semisynthetic diet for 16 days seemed to be limited to seminiferous tubular cross sections containing stages X to XIV of spermatogenesis, but after 28 days all tubular cross sections showed extensive spermatogenic cell destruction. No significant pathological changes were observed in the testes of rats fed 0.8% theobromine in the pulverized commercial diet for 21 days; spermatogenic cell degeneration and necrosis and multinucleate cell formation were seen after 28 days in seminiferous tubular cross sections containing the early stages of spermatogenesis, but sections containing stages X to XIV were spared or were much less involved. Atrophy of the thymus gland occurred earlier than testicular damage on each respective dietary regimen containing theobromine and was more severe in rats given theobromine in the semisynthetic diet.

Observations on autoimmune orchitis in sterile mice carrying a recessive lethal mutation at the T/t complex exhibiting spontaneous allergic orchitis.

Electron microscopic observations of testes of sterile, backcross T/tw18 mice which spontaneously develop allergic orchitis have demonstrated accumulations of lymphocytes and occasional plasma cells between seminiferous tubules in affected mice. Many lymphocytes appeared to be insinuated amongst cytoplasmic processes of the peritubular adventitial cells which, in most samples, provided a barrier to direct infiltration of the germinal epithelium by lymphocytes. Although lymphocytes were rarely observed within the seminiferous epithelium, extensive degeneration of spermatogenic cells was observed within affected tubules. Sertoli cells phagocytosed degenerating germ cells at all stages of differentiation. In-vitro co-cultivation of syngeneic T/tw18 spleen and testicular cells revealed that testicular cells from sterile T/tw18 mice failed to activate suppressor T lymphocytes; consequently, the syngeneic splenocytes displayed a vigorous proliferative response to testicular autoantigens. Testicular cells from younger, fertile T/tw18 males, on the other hand, behaved like testicular cells from normal mice, triggering suppressor T cell activity and, thereby, abrogating proliferation of splenocytes. These results suggest genetic factors, introduced in the course of inbreeding and associated with chromosome 17, are responsible for the failure of spermatogenic cells from sterile T/tw18 males to maintain normal tolerance to their own antigens in vivo; allergic orchitis is an extreme manifestation of the inability of the defective germ cells to initiate normal T lymphocyte mediated suppression of an immune response.

TOXICITY OF CHEMOSTERILANTS

The toxicity of a chemosterilant, metepa, tris [1-(2-methyl) aziridinyl] phosphine oxide, to rats and mice was studied.1) The acute oral LD50 value of metepa was 277 mg/kg for rats, compared with 292 mg/kg for mice. The dermal toxicity was 375 mg/kg for mice.2) In the subacute toxicity test on male rats, given orally metepa totalling 480 mg/kg in 8 days, metepa showed the typical properties as an alkylating agent. It caus-ed the profound effects against the proliferating tissues such as the testes and the bone marrow. The spleen was also affected. Further, the growth suppression and the reduction of blood cell counts were noticed.3) Daily oral administration (2.5-20 mg/kg/day) of metepa to rats for 84 days caused the growth suppression, the reduction of white blood cell counts and the testi-cular atrophy at higher levels. Severe degeneration of spermatogenic cells and occasio-nally multinucleated giant cells were observed microscopically. Although female rats appeared in general less sensitive to metepa than males, the histopathologic examination revealed the lesions in the ovaries even at a level of 5 mg/kg/day. No-effect level for three-month test appeared to be 2.5 mg/kg/day for male rats and was not fixed for females by the present experiment.

Cytology and kinetics of spermatogenesis in the rabbit.

Summary. The cycle of the seminiferous epithelium of the rabbit was divided into eight stages, using as criteria the shape of the spermatid nucleus, the location of the spermatids and spermatozoa in regard to the basement membrane, the presence of meiotic figures and the release of spermatozoa from the lumen. The relative duration (frequency) of Stages 1 to 8 were 27·7, 13·4, 7·3, 11·0, 4·1, 15·7, 12·2 and 8·6%, respectively. Each stem cell (Type A spermatogonium) divided to produce two Type A spermatogonia. One of these was the starting cell for the next generation, while the other gave rise to two intermediate-type spermatogonia. Three more spermatogonial divisions followed, producing sixteen primary spermatocytes from one Type A spermatogonium, as is characteristic for the bull and the ram, but unlike the rat, mouse and hamster. It was estimated that only 3·1 spermatids were generated from one primary spermatocyte, suggesting that in the rabbit there is considerable degeneration of spermatogenic cells during the two maturation divisions.

Sensitivity and Time of Degeneration of Spermatogenic Cells Irradiated in Various Stages of Maturation in the Mouse

Soon after the discovery of X-rays it was realized that these penetrating radiations induced striking alterations in living tissue, and in 1903 Albers-Sch6nberg (1) described radiation damage to the testis. Numerous investigations followed his initial report, and a voluminous literature has accumulated (for reviews, see refs. 2-4). Regaud and Blanc (5) were the first to realize the changes in sensitivity that accompany development of the different cell types, a subject which has received various interpretations (2, 6-13). The weight of experimental evidence indicates that spermatagonia are more sensitive than spermatocytes, spermatids, and sperm. Depletion of spermatogonia results in disappearance of cells in the order of their developmental sequence and eventually results in loss of sperm (2, 5, 8, 10, 11). However, a few type A (dusty) spermatogonia survive and eventually repopulate the germinal epithelium (8, 11-15). Therefore, both initial depletion and subsequent regeneration of spermatogenic elements depend on the response of spermatogonia. Paradoxically, it is the effect of radiation on spermatogonia that is the least understood. Regaud and Blanc (5) recognized the extreme sensitivity of spermatogonia, and Schinz and Slotopolsky (2) observed necrotic changes in spermatogonia as early as 2 hours after irradiation, with cessation of spermatogonial degeneration by 4 days. Regaud and Lacassagne (16), von Wattenwyl and JoMl (17, 18), and HIertwig (8) also considered necrosis of spermatogonia to be important. However, more recent reports have claimed that degenerative cells are rare (4, 11-13, 19, 20). On the basis of failure to observe degeneration, Eschenbrenner et al. (19) suggested that depletion of the germinal epithelium after irradiation was due to inhibition of mitosis of the most primitive cells, namely, the type A spermatogonia. A subsequent experiment with acute doses of X-rays was interpreted as supporting evidence for the hypothesis of mitotic inhibition (11). However, this hypothesis is in disagreement with the data of Langendorff (21), who observed a return to normal mitotic