Recent Advances in Male Infertility Research

Abstract

Recent developments in the following areas of andrology are highlighted: varicocele; biochemical markers of epididymal function; genitourinary tract infection; evaluation of sperm motility; capacity for sperm fertilization; and the immunologic consequences of vasectomy. Discussion of the varicocele effect focuses on detection of thesubclinical varicocele, spermatic venography, Leydig cell functon, experimental models, and percutaneous venous treatment modalities. The size of the varicocele bears no relationship to its subsequent effects on spermatogenesis. Consequently, the "subclinical" varicocele, which is not palpable, becomes an important entity in the infertile patient. Use of a Doppler ultrasonic stethoscope for the detection of the nonpalpable varicocele and use of scrotal thermography have been reported although caution is advised with these techniques. The stress pattern is a nonspecific response of the germinal epithelium to a stimulus or the lack of a stimulus. Genitourinary infection or endocrinopathy can also cause an increased number of ejaculated immature sperm. Spermatic vein ligation is not justified in an infertile patient with a seminal stress pattern but without clinial evidence of a varicocele. Varicocelectomy also is unjustified in a patient with a palpable asymptomatic varicocele in the absence of a stress pattern. Venography in patients with varicocele should be reserved for individuals in whom persistence of a palpable or subclinical varicocele and abnormal semen parameters are observed following spermatic vein legation. It is also a research tool and can prove helpful in providing more information about testicular venous drainage. It may provide a vehicle for percutaneous treatment of the varicocele. Recent attention has been directed to a possible correlation between the presence of varicocele, Leydig cell function, and testosterone synthesis. The seminal stress pattern has been successfully produced in monkeys by a 90% constriction of the left renal vein between the vena cava and spermatic vein. The results indicated a bilateral testicular effect based on testicular biopsies. The conventional treatment for varicoceles is surgery. Recently, there have been reports of percutaneous, fluoroscopic treatment of these lesions. Originally considered to be a passive conduit for sperm transport, it is now evident that the epididymis is actively involved in the maturation of spermatozoa. The applicability of epididymal markers will be based primarily on the relative ease of determination in a clinical laboratory. Several newer methods for determining sperm motility -- turbidimetric techniques, laser light scattering techniques, and photographic tracking of sperm movement -- have been reported in an effort to increase objectivity, provide accurate records of sperm motilit, and study patterns of sperm movement and the effects of various exogenous agents. Vasectomy results in sperm antibody production. The presence of circulating sperm antibodies after vasectomy raises the possibility of systemic effects.