Thyroid gland and epididymal sperm motility in rats

The purpose of this research was to investigate the effect of hypofunction of the thyroid gland, caused by radioactive suppression of the gland, on the pattern of spermatozoa motility in different segments of the rat epididymis. Thyroidectomy was obtained by i.p. infection of 270 microCi of I-131. After about 30 days, the animal reached hypothyroidism as determined by serum level of T4. When the motility pattern of the sperm obtained from the epididymis of normal rats was compared to that of hypothyroid animals, a drop in the parameter of path velocity (VAP), progressive velocity (VSL), and track speed (VCL) were detected. Hypofunction was associated with decreasing sperm motility in the epididymis. In thyroidectomized rats injected with T4, no sperm motility changes were observed.