In male rats born to dams treated with 125 mg/kg-BW per day, 15.6% retained nipples, 18.75% showed incomplete PPS, 12.5% showed cleft phallus and hypospadias, 3.1% (one animal) had an exposed os penis, and 6.2% (two animals) had vaginal pouches. Weights of ventral prostate (P = 0.048) and epididymis (P = 0.011) were reduced. Unadjusted testis weights were reduced compared with those of controls (P = 0.0325; Table 3) but not when body weight adjustment was used (P = 0.0907).
At 62.5 mg/kg-BW per day, one male (2.2%) retained nipples and another showed incomplete preputial separation. Body weight-adjusted weight reductions were observed with the epididymis (P = 0.0105) and ventral prostate (P = 0.0478). One male (1.9%) at 31.25 mg/kg-BW per day retained nipples but no other reproductive malformations were observed in this group.
Treated animals showed testicular histopathology (Fig. 9) that included atrophy or vacuolization of the seminiferous epithelium (chi-square = 76.6, P < 0.01). Significant differences in percentages of affected animals compared with controls (P < 0.01) were observed in the three highest treatment groups (Table 3). Analysis of animals receiving a histopathology score of 2 or higher (chi-square = 36.5, P < 0.01) showed a dose-dependent increase in severity of the effect and percentages of animals in the 125 and 250 mg/kg-BW per day groups were significantly affected (P < 0.01) compared with that of controls. Testes were not always equally affected within individuals. At 250 mg/kgBW per day the most severe histopathologies were unilateral.
Necropsy of Mature Female Offspring
In females necropsied as adults, no differences were found between treatment groups in organ weights or in measurements of anogenital distance, anovaginal distance, phallus length (from anterior edge of vaginal orifice to phallus tip), kidney to ovary distance, or vertical kidney to ovary distance (Table 4). There was no indication of female masculinization at necropsy.
FIG. 8. Adult testicular and epididymal morphology from controls and a high-dose (250 mg/kg-BW per day) PZ-treated animal. Note that the testes of the treated animal are flaccid and the testicular artery appears malformed. Control vs. high-dose testis weights were 3.5 ± 0.08 vs. 3.0 ± 0.15 g (P < 0.05) and respective epididymal weights were 1.3 ± 0.02 vs. 0.99 ± 0.1 g (P < 0.05).
TABLE 3. Comparison (mean ± SEM) of organ weights (g) and testicular histopathology in male offspring of dams dosed with PZ from GD 14-18.a
a Significance of treatment effects on organ weights were determined using analysis of covariance with bodyweight as a covariate; percentages of animals showing histopathology were compared using Fisher’s Exact test. b LABC = combined weight of levator ani and bulbocavernosus muscles. c n = 3.
d NA = not applicable because deformities prevented objective measurement.
P < 0.05 compared to controls
P < 0.01 compared to controls.
FIG. 9. Seminiferous tubule histological sections. A) Normal testis. B) Testes from an adult rat receiving a 5-day 250 mg/kg-BW per day gestational PZ exposure. Seminiferous tubules show atrophy and vacuolization. Bar = 100 ^m.