DDB1 Regulates Sertoli Cell Proliferation and Testis Cord Remodeling by TGFß Pathway.

Testis cords are the embryonic precursors of the seminiferous tubules. Development of testis cords is a key event during embryonic testicular morphogenesis and is regulated by multiple signaling molecules produced by Sertoli cells. However, the exact nature and the cascade of molecular events underlying testis cord development remain to be uncovered. In the current study, we explored the role of DNA damage binding protein 1 (DDB1) in Sertoli cells during mouse testis cord development. The genetic ablation of Ddb1 specifically in Sertoli cells resulted in the compromised Sertoli cell proliferation and disruption of testis cord remodeling in neonatal mice. This testicular dysgenesis persisted through adulthood, resulting in smaller testis and low sperm production. Mechanistically, we observed that the DDB1 degradation can stabilize SET domain-containing lysine methyltransferase 8 (SET8), which subsequently decreases the phosphorylation of SMAD2, an essential intracellular component of transforming growth factor beta (TGFß) signaling. Taken together, our results suggest an essential role of Ddb1 in Sertoli cell proliferation and normal remodeling of testis cords via TGFß pathway. To our knowledge, this is the first upstream regulators of TGFß pathway in Sertoli cells, and therefore it furthers our understanding of testis cord development.

Dilemma of adolescent varicocele: long-term outcome in patients managed surgically and in patients managed expectantly.

OBJECTIVE: To evaluate outcomes of adolescent varicocele in the case of surgical versus conservative management. METHODS: 173 adolescent patients presenting with varicocele were evaluated clinically and sonographically to define varicocele grade and testicular volume. The patients were divided into 2 groups: A (53) with testicular size discrepancy >20% and bilateral varicoceles; B (120) unilaterally affected patients with testicular size discrepancy <20%, who were randomly allocated into 2 equal sub-groups (B1 & B2) of 60 patients. Group A & B1 patients underwent 3× loupe magnified inguinal varicocelectomy while B2 patients were conservatively managed. RESULTS: Mean patient age was 14.3 years with mean testicular volume of 11.75 mL and 10.15 mL for right and left testicles, respectively. There were no significant differences between sub-groups B1 & B2 for age, mean testicular volume, size discrepancy and varicocele grade. Mean follow-up of group A & B1 patients was 78 months showing grade I varicocele recurrence (4 cases), catch-up growth in 70% of cases and normal semen analysis in all cases. Mean follow-up of group B2 patients was 79 months showing catch-up growth in 50% of cases and normal semen analysis in all but 1 case. Four cases were shifted to surgical treatment due to reduction of testicular size (2 cases), varicocele upgrade (1 case) and oligoasthenospermia (1 case). At the last follow-up, the mean testicular volume for groups A, B1 & B2 was 16.2, 16.45 & 16.3 mL for right testes and 14.7, 15.6 & 15.2 mL for left testes, respectively. There was significantly better catch-up growth in sub-group B1 compared to B2 but the testicular volume was not statistically different. CONCLUSIONS: Although adolescent varicocelectomy was associated with a higher percentage of patients showing testicular catch-up growth, the mean testicular volume was not significantly different. Further studies are needed to report on paternity among those patients.

The anatomy of the cremaster muscle during inguinoscrotal testicular descent in the rat.

BACKGROUND: Extrapolation of rat testicular descent studies to humans has been criticized because of anatomical differences of the cremaster muscle. Human cremaster is described as a thin strip rather than a large, complete sac as in rats, which is proposed to be more important in propelling the testis during descent. This study investigated cremaster muscle anatomy and ontogeny in both normal and cryptorchid rat models. METHODS: Gubernacula from 4 groups of neonatal rats were sectioned longitudinally and transversely: normal Sprague-Dawley, capsaicin pretreated, flutamide pretreated, and congenital cryptorchid rats. Gubernacula were stained with hematoxylin-eosin, Masson trichrome, and desmin immunohistochemistry to study muscle development. RESULTS: Myoblasts are more numerous at the gubernacular tip, whereas the most differentiated muscle is proximal. Rat cremaster develops as an elongated strip rather than a complete sac derived from abdominal wall muscles. Flutamide and capsaicin pretreatment disrupts development. CONCLUSION: Rat cremaster muscle develops as a strip, bearing close resemblance to human cremaster muscle, permitting extrapolation of cremaster function to human testicular descent. The cremaster muscle appears to differentiate from the gubernacular tip during elongation to the scrotum, and requires intact sensory innervation and androgen.

Sex difference in target seeking behavior of developing cremaster muscles and the resulting first visible sign of somatic sexual differentiation in marsupial mammals.

Cremaster muscles are present in both male and female developing and adult marsupial mammals. They are complex structures and composed of several distinct bundles of striated muscle fibers provided with: (1) a distinct and extensive innervation; (2) a distinct blood vascular supply; (3) a distinct tendineous origin on the anterosuperior iliac spine; and (4) distinct target structures. The muscles thus seem to be separate anatomical entities and not a part of one or more of the layers of the ventral abdominal wall musculature. Cremaster muscles in males are elongated, are larger than in females, and for the most part are a component of the funiculus spermaticus. They insert on the distal part of the tunica vaginalis. The distal parts of the muscles in females are flattened ("fan shaped") and insert over a broad area on the dorsal borders of the mammary glands. Muscles in males have no relation whatsoever to the male mammary glandular rudiments. Muscles in females are attached at the base of the uterine round ligament. The remarkable sex difference in target structures of marsupial cremaster muscles becomes noticeable during perinatal life when outgrowing muscles take a different path in males and females. The initial appearance of this sexually dimorphic trait precedes the sexual differentiation of the genital ducts and external genitalia. In fetal males, the cremaster muscles grow in the direction of the site where scrotal bulges initially appear in the subcutaneous layers and later on the inguinal skin surface. They also take the gubernacular core of the ventral abdominal wall and the attached peritoneal epithelium with them during this outgrowth process. Consequently, this results in the development of a slitlike evagination of the abdominal lumen as the primary step to development of the processus vaginalis, while the testis and adjacent mesonephros and its duct are still attached to the posterior abdominal wall. In fetal females, the outgrowing cremaster muscles pass along the gubernacular core and, subsequently, this structure develops further as the tip (attached to the tubo-uterine junction) of the intra-abdominally protruding and further developing uterine round ligament. The female cremaster muscles grow further into caudal direction to shape a dorsal border of the developing mammary glands. The early onset of this sexually dimorphic outgrowth of cremaster muscles indicates that the "classical hormones" of sexual differentiation (anti-Müllerian hormone [AMH] and steroidal androgens) are not involved in this process. It could thus depend on primary genetic control with male development associated with the male-limited activity of genes on the Y-chromosomes and female development as the default process. Alternatively, the process in males could be under the control of an as yet unidentified third fetal testicular hormone involved in sexual differentiation processes which must then show an unexpectely early (i.e., perinatal) onset of its secretion.