Species: Cynomolgus monkey Strain/breeder: Guangxi (China) Sex: Male Age: Approx 3.5 years Study type: Systemic daily intragastric (gavage) application, 13 weeks Treatment: 100 mg/kg/day synthetic compound with estrogenic activity Animal status: Testicular biopsy 3 weeks before first treatment. Final sacrifice after 13 weeks of treatment. Clinical findings: Edema, reddening of the prepuce and the scrotum. Prepuce not retractable. Testes not palpable in the scrotum after some week of treatment. Swelling of the mammary gland. Organ(s): Testes Gross finding(s): Testes reduced in size, gray/white discoloration. Testes close to inguinal region, can't be moved into the scrotum. Staining: H&E Literature: -

Fig. 1: Biopsy, control before study (136k) Fig. 2: Biopsy, treated animal before study (93k) Fig. 3: Control testis after 13 weeks (147k) Fig. 4: Treated testis after 13 weeks (95k)

Abstract

R. Ernst

Schering AG, Experimentelle Toxikologie, Berlin, Germany

Key words: Cynomolgus monkey, estrogen, testes

This report describes the effect of systemic treatment with a synthetic estrogen on the genital organs of male cynomolgus monkeys. To assess the state of testicular maturation of the animals, biopsies from the testes were taken prior to the treatment. Effects of treatment with estrogen encompassed testicular atrophy, preputial and scrotal edema and reddening of the skin, resembling the sex-skin formation in female cynomolgus monkeys during estrus. The use of testicular biopsies in toxicological studies involving hormonal active substances is discussed.