Gestational Exposure to Ethane Dimethanesulfonate: DISCUSSION(2)

It was possible that the elevated ex vivo T production in the adult merely resulted from an increase in number of LCs rather than an increase in LH stimulation per LC. Although it appeared that there was indeed an increase in LC numbers in the EDS-exposed males, it was necessary to perform stereologic analysis to discriminate an actual increase in LC numbers versus the appearances of LC hyperplasia because of seminiferous tubule damage, a historic controversy. Accordingly, LCs were immuno-stained for P450scc enzyme and enumerated. The observed increase in the interstitial area resulted from diminished tubule volume, and the apparent increase in the number of LCs was a consequence of this tubular alteration. It was surprising to observe not only a decrease in the overall number of LCs but also a decrease in the volume of an individual LC. This alone indicates a permanent lesion in LC development; a defect that is presumably compensated by the observed increase in serum LH and the resulting increase in T production by these adult LCs.

An evaluation of testicular histology in neonatal, prepubertal, and adult testes from EDS-exposed mice demonstrated that EDS exposure of the male fetus results in a persistent deficit in spermatogenesis. The maturation of the testis, i.e., the onset of spermatogenesis, was delayed as evidenced by the predominance of Sertoli cell only tubules throughout the development of the testes in EDS-exposed offspring. The fetal testes of EDS-exposed mice contained large LC aggregates within the interstitium; these aggregates were juxtaposed to tubules with disorganized seminiferous epithelium. A similar phenomenon has been observed in the fetal testes of rats exposed gestationally to DEHP, an antiandrogenic chemical that does not bind to the androgen receptor but does decrease fetal T production. In the prepubertal mouse, seminiferous tubules in EDS-exposed offspring contained Sertoli cell only profiles. It is likely that the appearance of intraepithelial vacuoles is due partly to the absence of germ cells. Because the accumulation of vacuoles in conjunction with chemical disruption of spermatogenesis is a common, nonspecific response to a variety of insults on the testis, this may or may not be a direct consequence of EDS exposure.

Category: Dimethanesulfonate

Tags: Leydig cells, testis, testosterone, toxicology