Changes in the epididymal ultrastructure in hypothyroid rats

The purpose of this research was to investigate the effect of hypothyroidis m on the ultrastructure of the rat cauda epididymis. Thyroidectomy was obta ined by ip injection of 270 mu Ci of I-131 per rat. One month later, severa l portions of cauda epididymis were examined in an electron microscope. Mor phological and physiological differences were detected in the cauda epididy mis of the hypothyroid animals when compared to the control normal rats. Th e hypothyroid condition was associated with a decrease in the height of the cells and diminution of the internal lumen, number of mitoses, and chromat in decondensation. Hypothyroidism produces a remarkable impairment of epidi dymal morphology that could be mainly responsible for the functional altera tions that lead to the dramatic slowing of spermatozoa motility, commonly s een in severe thyroid insufficiency.