Changes in the epididymal ultrastructure in hypothyroid rats

The purpose of this research was to investigate the effect of hypothyroidism on the ultrastructure of the rat cauda epididymis. Thyroidectomy was obtained by i.p. injection of 270 microCi of 131I per rat. One month later, several portions of cauda epididymis were examined in an electron microscope. Morphological and physiological differences were detected in the cauda epididymis of the hypothyroid animals when compared to the control normal rats. The hypothyroid condition was associated with a decrease in the height of the cells and diminution of the internal lumen, number of mitoses, and chromatin decondensation. Hypothyroidism produces a remarkable impairment of epididymal morphology that could be mainly responsible for the functional alterations that lead to the dramatic slowing of spermatozoa motility, commonly seen in severe thyroid insufficiency.