Induced Varicoceles in Rhesus Monkeys*†*Publication No. 993 from the Oregon Regional Primate Research Center. Supported in part by National Institutes of Health Grants HD05969 and RR00163.†Presented at the Thirty-Fourth Annual Meeting of The American Fertility Society, March 29 to April 1, 1978, New Orleans, La. ACMI Prize Paper

Varicocele and left renal vein compression

Several current theories concerning the possible etiology of varicocele are critically reviewed. The possibility of arterial compression of the left renal vein, probably by the superior mesenteric artery is elaborated upon. Since direct experimentation is impossible because of the exclusively human character of this disease, a "triple indirect approach" is adopted. Three differently directed studies are conducted: intraoperative antegrade spermatic phlebography visualizing the left renal vein, anatomic dissection of the left renal vascular pedicle, and intraoperative marking of the superior mesenteric artery and the left renal vein for in vivo studies of their relationships. Because the outcomes of these three pathways converge and focus on the superior mesenteric artery compression of the left renal vein, it is concluded that this is a probable contributing mechanism in the etiology of varicocele.

Surgical induction of varicocele in the rabbit

Surgically induced varicoceles were created in male rabbits of proven fertility by partially occluding the left lumbotesticular trunk, which receives the left testicular vein before draining into the left renal vein. Semen was collected every 2 weeks following surgery and left testicular biopsy was performed at 2, 4, 8 and 13 postoperative weeks. Tissue was processed for light and electron microscopy. Animals were sacrificed at 20 postoperative weeks. Left testicular vein dilatation was observed at autopsy (20 weeks postoperative), as were changes in semen quality. These included an increase in the number of round germ cells and abnormal spermatozoa, as well as a decrease in sperm numeric density and motility. Seminiferous tubule pathology was variable and germ cell sloughing was observed as soon as 8 weeks following surgery. Spermatids were maloriented relative to Sertoli cells and Sertoli-germ cell junctional complexes were structurally abnormal. Results indicate that surgical induction of varicocele in the rabbit leads to altered spermatogenic function and decreased semen quality similar to that described in humans. Epithelial disruption appears to be a phenomenon of the adluminal testicular compartment and apical Sertoli cell cytoplasmic degeneration may account for the poor semen quality associated with varicocele.

Testis temperature, infertility, and the varicocele paradox

The author presents arguments which favor elevated temperature of the testis and adnexae as an important factor in patients with poor semen seen in varicocele and "idiopathic" infertility. This appears to be primarily the result of disturbed thermoregulation due to internal spermatic vein retrograde blood flow. Elevated testis temperature without varicocele may be present in as high as 54% of all patients with "idiopathic" infertility. The prevailing theory in the United States is that the varicocele's bilateral effect is due to a substance noxious to spermatogeneis which is carried to both testes by retrograde internal spermatic vein blood flow and via crossover to the contralateral testis. A review of the published evidence for the crossover does not confirm its presence in the deep circulation of the contralateral testis, but rather its restriction to the superficial contralateral scrotal venous drainage. A simpler explanation for the bilateral effect of varicocele on spermatogenesis and sperm maturation by the epididymis is a gradient to the contralateral testis from the affected testis which results in demonstrable elevated temperature in both.