Ultrasonographic findings in the epididymis of pediatric patients with testicular torsion.

INTRODUCTION: Although grayscale ultrasound and color Doppler ultrasound characteristics of the torsed testis are well established in the literature, less is known about its anatomic partner: the epididymis. OBJECTIVE: The purpose of this study was to describe the ultrasound characteristics of the epididymis in pediatric patients with testicular torsion, and to describe their potential role as prognostic criteria for testicular salvage outcomes. STUDY DESIGN: During a retrospective review of 217 pediatric patients with acute testicular torsion during 2009-2016, morphological features of the epididymis from scrotal ultrasounds (size, parenchymal characteristics, and vascular flow of both epididymis heads), as well as patient demographics, time duration, surgical outcomes, histopathology results, and follow-up periods were analyzed. RESULTS: Mean epididymis size and twisting degree were significantly higher in the torsed testes than in the contralateral epididymis (P < 0.001) (Summary table). Cystic structures in the epididymis were identified: a higher number of cysts was associated with testicular non-viability (P = 0.025) and higher twisting degree (P = 0.017). Histopathologic examination showed that these spaces were infiltrated connective tissue most likely formed by venous congestion and vessel rupture. DISCUSSION: Scrotal ultrasound can provide information on testicular morphology and viability, as well as morphological changes in the epididymis over time in pediatric patients with testicular torsion. These findings may provide potential prognostic information regarding testicular viability, as a higher number of cystic spaces in the epididymis was associated with a higher rate of testicular non-viability and a higher twisting degree. In addition, the epididymis size (volume) can change during the time course of the ischemic state. CONCLUSIONS: This was the first study to describe and analyze epididymis ultrasound findings in pediatric patients with testicular torsion and to correlate them with testicular salvage outcomes. Further prospective studies are needed to determine the role of epididymis ultrasound findings as a potential pre-operative prognostic tool.

Sohlh1 is essential for spermatogonial differentiation.

Spermatogonia are adult germline stem cells that can both self-renew and differentiate into spermatocytes. Little is known about factors necessary for spermatogonial differentiation. We identified a novel germ-cell-specific transcription factor that we named Sohlh1 (testis and ovary expressed basic helix-loop-helix (bHLH) transcription factor). In males, Sohlh1 is preferentially expressed in prespermatogonia and Type A spermatogonia. Loss of Sohlh1 causes infertility by disrupting spermatogonial differentiation into spermatocytes. Seven-day-old testes without Sohlh1 still express the testis-specific transcription factors Etv5, Taf4b, Zfp148, and Plzf, overexpress a novel Tohlh2 bHLH transcription factor, but lack LIM homeobox gene Lhx8 and show reduced expression of Ngn3. Sohlh1 represents the first testis-specific bHLH transcription factor that is essential for spermatogonial differentiation.