Refractoriness of the immature rat epididymis to the early cadmium lesion.

Ninety minutes after i.p. injection of 3 mumol of cadmium chloride/100 g body weight into immature, 15 day-old rats, the endothelial intercellular junctions of the caput epididymis capillaries showed none of the lesions such as loss of junctional associated ectoplasmic microfilaments, separation of interdigitated leaflets, disassembling of interendothelial tight junctions, passage of blood plasma and cells into the pericapillary space, platelet clumping and disintegration, and intracapillary clotting, which after the same dose are found in sexually mature rat epididymides. The resistance of the immature, physiologically intraabdominal epididymal capillary endothelium reminds one of the protection against cadmium that is brought about by surgical cryptorchidism in adult mature rats. We suggest that either local enzyme immaturity or the abdominal temperature (5 degrees C than scrotal temperature) may protect zinc enzymes against displacement by cadmium.