reproduction > testis > histopathology > estrogen antagonist effects

see also: estrogenic effects - androgenic effects - androgen antagonist effects
estrogen antagonist effects in the testis - spermatogenesis
320 µg/L (3w)

uniform leptotene

mixed leptotene / zygotene
After exposure to tamoxifen, there is dissynchrony of spermatogenesis, i.e. spermatogenic cells of subsequent stages occur within a single spermatogenic cyst (right, compare to control, left). This change appears to be dose-dependent.

All images were taken from adult male zebrafish; H&E staining.

uniform zygotene

mixed leptotene / zygotene / pachytene


various pachytene

uniform spermatid

mixed leptotene / spermatid
effects of tamoxifen on the testicular interstitium

adult male zebrafish exposed to 320 µg tamoxifen /L for 3 weeks (lower image); reference in upper image. H&E staining.
After exposure to tamoxifen (bottom), the interstitium of the testis has a distended, edematous appearance, compared to the control testis (top). This feature is associated with the presence of dilated capillaries.
This distended interstitium contains large clusters of interstitial Leydig cells, in contrast to the control animal, where these Leydig cells mostly occur singly or in small clusters.

Similar large clusters of Leydig cells were found after exposure to the anti-androgen flutamide.