AGE-RELATED-CHANGES IN BLOOD-CONCENTRATIONS OF FSH, LH AND TESTOSTERONE AND TESTICULAR MORPHOLOGY IN A NEW RAT STERILE MUTANT WITH HEREDITARY ASPERMIA

A new rat mutant showing aspermia was investigated. Groups of 4-7 muta nt male rats were killed at 3, 5, 10, 15 and 25 weeks of age. Examinat ion by microscope showed apparent abnormalities in the seminiferous ep ithelium from 3 weeks of age onward. Inclusion-like bodies were observ ed in the cytoplasm of pachytene spermatocytes from 3 weeks old and in stead of spermiation, polynuclear giant cells were formed within the s eminiferous epithelium after 5 weeks of age. Histological analysis of seminiferous epithelium of adult mutant rats also showed a marked decr ease in the number of preleptotene, leptotene and pachytene spermatocy tes and tubules containing only spermatogonia and Sertoli cells in the seminiferous epithelium increased with age. However, the combination of other cellular elements of germ cells in the seminiferous epitheliu m was similar to that in normal rats and the distribution rate of thes e seminiferous tubules was close to that of normal rats, indicating th at cyclicity of seminiferous epithelium was still maintained in the mu tant rats despite the lack of spermiation. Plasma concentrations of FS H and LH were significantly higher in the mutant male rats than in nor mal male rats at 5 and 10 weeks of age onward, respectively. Plasma co ncentrations of testosterone were lower in the mutant male rats than i n normal male rats. Silastic capsules containing testosterone were imp lanted into the unilateral testis of adult mutant male rats and animal s were autopsied 5 weeks later. However, intratesticular administratio n of testosterone did not affect restoration of spermatogenesis. These results indicate that the arrest of spermatogenesis had occurred from the first cycle of spermatogenesis and the primary defect in the muta nt is not gonadotrophin and testosterone deficiency.