Investigations of arterio-venous anastomoses in the spermatic cords and blood supply, oxygen consumption and testosterone production of scrotal and abdominal testes in the pig.

This study has investigated blood flow from the testicular artery to the pampiniform plexus in the spermatic cord of pigs. Testosterone levels, oxygen tension and the degree of acidity were measured in arterial and venous blood vessels of scrotally and abdominally located testes. Haemoglobin oxygen saturation was derived from the oxygen dissociation curve. Blood flow to abdominal and scrotal testes and epididymides was measured using the radioactive microsphere technique. Average blood flow to the scrotal testes and epididymides was 21 and 8 ml/min, respectively, in normal pigs. In unilaterally cryptorchid pigs average blood flow to the scrotal testis and epididymis was 23 and 6 ml/min, respectively, and to the abdominal testis and epididymis 4.2 and 1 ml/min. In pigs with bilateral scrotal testes oxygen consumption was 16 mumol O2/min/100 g. In unilaterally cryptorchid pigs oxygen consumption by the scrotal testis was 18 mumol O2/min/100 g, compared with 10 mumol O2/min/100 g by cryptorchid testes. From the percentage oxygen saturation in the various blood vessels it was calculated that 29-42% of testicular arterial blood was flowing through arteriovenous anastomoses between the testicular artery and the pampiniform plexus in the spermatic cord, thus bypassing the capillary net of the abdominal testes of unilaterally and bilaterally cryptorchid pigs. These results were supported by the testosterone measurements. In the spermatic cord of scrotal testes no blood bypassed the capillary net of the testes.