Induction of Müllerian duct derivatives in testicular feminized (Tfm) mice by prenatal exposure to diethylstilbestrol

Androgenic regulation of ventral epithelial bud number and pattern in mouse urogenital sinus

The ventral urogenital sinus (UGS) of control male mice has two rows of 3-4 prostatic buds at birth, but how androgens regulate ventral bud (VB) number and patterning is unclear. VBs in both sexes appeared to be a mixture of prostatic and urethral buds. UGSs from Tfm male and antiandrogen (flutamide)-exposed mice had small VBs, suggesting that initiation of some VBs is androgen independent. Tfm male mice are widely considered completely androgen insensitive yet their UGSs were 5alpha-dihydrotestosterone (DHT)- responsive. VBs (6-8) were generally distributed bimodally on the left-right axis at both minimal and normal male androgen signaling. Yet control females and DHT-exposed Tfm males had 13-14 VBs, whose left-right distribution was fairly uniform. These results suggest that VB number and distribution respond biphasically as androgen signaling increases from minimal, and that androgens regulate bud specification. Complete VB agenesis by the selective budding inhibitor 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) required high androgen signaling.

Müllerian remnants of male mice exposed prenatally to diethylstilbestrol

Prenatal exposure of males to diethylstilbestrol (DES) results in reproductive tract teratogenesis, ie, retention of Müllerian duct remnants. The potential of these remnants to develop pathological changes has not been studied. Therefore, pregnant outbred CD-1 mice were subcutaneously injected with daily doses of DES (100 micrograms/kg) on days 9 through 16 of gestation. DES-exposed male offspring and age-matched control male mice were sacrificed at 10 to 18 mo of age and examined for reproductive tract abnormalities. Prominent Müllerian remnants were observed in 268 out of 277 (97%) of the DES-exposed male mice. These remnants differentiated into "femalelike structures" homologous to oviduct and uterus. The Müllerian remnants were often enlarged and cystic and shared supporting connective tissue with adjacent male structures. Previously reported lesions, termed "epididymal cysts," were determined histologically to be cystic "oviductlike" structures and were, therefore, considered a Müllerian duct abnormality. Pathological changes in these male oviductal and uterine homologs included benign and malignant lesions. In addition, epididymal structures were altered. Inflammation and sperm granulomas were prevalent in DES-treated mice as young as 10 mo old but were only observed in control mice at 18 mos. Cysts of epididymal duct origin, hyperplasia, and adenoma of the epididymal duct were also observed. No comparable abnormalities were noted in 122 control males of corresponding ages. The data presented in this report demonstrated that transplacental exposure to DES affected the differentiation and normal development of the male genital tract involving both the Müllerian (paramesonephric) and Wolffian (mesonephric) ducts. The long-term changes in these tissues include lesions, some of which resembled neoplasia although the natural history of the lesions is not known. Moreover, some previously described abnormalities referred to as "epididymal cysts" were associated with tissues derived from embryonic female origin.

Accelerated differentiation in seminiferous tubules of fetal mice prenatally exposed to ethinyl estradiol

Ethinyl estradiol (EE) in olive oil (0.02, 0.2, or 2.0 mg/kg) administered to pregnant mice on days 11 to 17 of pregnancy induced abnormal differentiation of gonocytes and fetal Sertoli cells in male fetuses on day 18 of gestation. Light and electron microscopic examination of the testes showed fewer darkly stained prospermatogonia and more lightly stained prospermatogonia in the experimental than in the control fetuses. Widespread degeneration and lysis of gonocytes were seen only in the experimental mice. No spermatogonia type A could be detected. In spite of comparable mitotic rates in the Sertoli cells of the experimental and control mice and more dark Sertoli cells with well developed smooth endoplasmic reticulum (SER) in the experimental mice, one of the functions of fetal Sertoli cells was suppressed: there were fewer dark slender Sertoli cells with long processes extending to the centers of tubules and more contact areas with gonocytes, phenomena which may play a role in the migration of gonocytes towards the periphery of the tubules. More Sertoli cells were detected in the undescended than the descended testes exposed to the highest dose of EE. These morphological findings indicate that prenatal exposure to EE induces acceleration of prespermatogenesis and disturbances in the initiation of spermatogenesis and in the mechanical function of Sertoli cells.

Gonadal dysgenesis induced by prenatal exposure to ethinyl estradiol in mice

Daily oral administration of ethinyl estradiol (0.02, 0.2, or 2.0 mg/kg of body weight) to pregnant Jc1:ICR mice resulted in ovotestis and intra-abdominal testis with persistent Müllerian duct and Wolffian duct in male fetuses and ovarian hypoplasia in female fetuses when it was given from day 11 through day 17 of gestation (before gonadal differentiation in the fetus). The ovotestis consisted of testicular and ovarian portions. In the testicular portion, a few solid seminiferous tubules containing spermatogonia, some with pachytene nuclei with Sertoli cells and compact interstitial tissue including Leydig cells, were seen. In the ovarian portion, pachytene nuclei were seen. The intra-abdominal testis was smaller and contained more spermatogonia per tubule in cross section than the control testis. These findings suggest that in male fetuses ethinyl estradiol affects Sertoli cell differentiation resulting in suppression of Müllerian inhibiting factor. On the other hand, in the ovarian hypoplasia, the primordial follicles and follicular cells in a primordial follicle were significantly decreased in number, and the number of the degenerated primordial follicles was significantly increased. It seems likely that ethinyl estradiol affects the intimate contact between follicular cells and oocytes to cause degeneration of primordial follicles.