histophysiological study of vasectomized rats an histophysiological evaluation was performed of adult rat testes 30 days after vasectomy a higher frequency of stage viiviii of the tubular cycle was observed indicating sperm accumulation seminiferous tubules and tubular lumen having increased diameters were also observed but these results cannot be explained only in terms of increase in retrograde intratubular pressure the rise in basal gonadotrophin levels as well as in testosterone levels observed under basal conditions and 30 and 60 min after stimulation with human chorionic gonadotrophin hcg suggested hyperactivity of the leydig cells the observed increased frequency of leydig cells with smaller nuclear volumes may be correlated with higher luteinizing hormone levels the results are discussed in terms of the possible role of neuromotor components resected during vasectomy which may alter the spermatogenic and the secretory functions of the testis