ROLE OF THE HYPOGASTRIC NERVES IN SEMINAL EMISSION IN THE RABBIT

Abstract

The chronic effects of removal of the posterior mesenteric ganglion and the hypogastric nerves on the semen and reproductive organs were studied in male rabbits for periods varying from 3 days to 1 year. In all rabbits, initially, spermatozoa and gel were absent from the ejaculates, which were grossly contaminated with urine. In one rabbit, in which the neck of the bladder was ligated, nothing was collected in an artificial vagina after orgasm. Libido was normal in all cases. Spermatozoa usually reappeared in the ejaculates in 20 to 40 days; sperm counts were then normal or greater than normal although large numbers of spermatozoa caused a permanent distension of the distal part of the ductus deferens and epididymis. This suggested a failure of the normal absorption mechanism in the epididymis. The seminal vesicles were distended with secretion until 14 to 16 weeks after operation. At that time gel reappeared in the ejaculate and the seminal vesicle and prostates regained normal size. In no animal was there recovery of the bladder sphincter. The sympathetic nervous pathways via the hypogastric nerves are responsible for seminal emission into the pelvic urethra and possibly for absorption of spermatozoa from the epididymis. No evidence was found that these sympathetic pathways influenced secretion in the seminal vesicle and prostate glands, ejaculation from the penile urethra, or subsidence of erection. Its effect on the testes was possibly mainly vasomotor. Alternative nervous pathways were apparently established for the seminal vesicle, prostate gland and the proximal part of the ductus deferens but not for the bladder sphincter, the distal part of the ductus deferens, or the epididymis.