Regional blood flow in the epididymis of the rat and rabbit : effect of efferent duct ligation and orchidectomy

Summary. Relative blood flow along the epididymis of the rat and rabbit has been measured using the isotope fractionation technique of Sapirstein (1958). In the rabbit, by simultaneously measuring cardiac output by the thermodilution technique, blood flow was expressed in absolute units. In both species, portions of the caput and corpus regions were nourished by capillaries with high blood flow whereas the cauda had the lowest blood flow in the epididymis. Blood flow values \m=+-\S.E.M.recorded in fourteen rabbit epididymides were: mean blood flow 23\m=.\8\m=+-\1\m=.\9ml/100 g/min; high blood flow regions were: segments 2 and 3, caput epididymidis (34\m=.\8\m=+-\2\m=.\3and 34\m=.\3\m=+-\2\m=.\2 ml/100 g/min), and the corpus epididymidis (36\m=.\0\m=+-\0\m=.\9ml/100 g/min). Cauda epididymidis blood flow was 19\m=.\7\m=+-\1\m=.\8ml/100 g/min. There was no bilateral variation in blood flow in the testis or epi-didymis of rat or rabbit. Removal ofone testis or unilateral ligation of the efferent ducts caused a marked reduction of capillary blood flow in the caput region of both rat and rabbit epididymides after 7 days compared with the control epi-didymis. The effect was less striking elsewhere in the epididymis. The region of rich capillary blood flow in the corpus epididymidis in the rabbit coincides with the portion of the duct in which spermatozoa acquire the ability to fertilize