Neonatally administered diethylstilbestrol retards the development of the blood-testis barrier in the rat

Newborn rats were treated with 10 mug of diethylstilbestrol (DES) on altern ate days from the 2nd to the 12th postnatal day, and the testes were sequen tially examined up to 105 days of age by light, electron, and confocal lase r microscopy. In control rats, spermatozoa and step 19 spermatids were obse rved in stage VIII seminiferous tubules at 56 days of age. Spermatogenic ce lls in DES-treated rats differentiated normally from birth until 21 days or age, after which differentiation continued only to the pachytene-spermatoc yte stage. From this age onward, spermatogenic cells older than pachytene s permatocytes were not found until 56 days of age. After this point, the cel ls resumed differentiation and finally became spermatozoa by 91 days of age ; that is, 35 days later than control rats. Electron and confocal laser mic roscopy showed that in the normal rat, the formation of the ectoplasmic spe cialization between adjoining Sertoli cells was observed as early as 20 day s of age. In contrast, the specialization was not formed until 56 days of a ge in DES-treated rats. Furthermore, the delay in functional maturation of this structure as the blood-testis barrier was confirmed by intercellular t racer experiments. It is clear that neonatal administration of DES delayed the establishment of the blood-testis barrier for 4 weeks. Consequently, du ring this period, pachytene spermatocytes were exfoliated from the seminife rous epithelium without completion of meiosis.