The structure, morphometry and vascular perfusion of the testis in the rufous sengi (Elephantulus rufescens)

Abstract

Introduction and Materials and Methods: Sengis are testicondid, monogamous afrotherian mammals. The testes, pattern of testicular blood vessels and anatomical disposition of caudal vena cava were examined macroscopically in the rufous sengi (Elephantulus rufescens). Testicular structure was further studied microscopically and its components quantified using stereology. Results: The testes were cylindrical in shape and located caudolateral to the kidneys. The testicular arteries branched from renal arteries, ran to the respective testicles without close association with other vessels, while the veins ran straight to the caudal vena cava without pampiniform plexus or intimate association with cognate arteries. There were two caudal vena cavae that united after receiving the renal veins. The seminiferous tubules were bound by a peritubular boundary tissue with a single layer of myoid cells while the interstitial tissue had polyhedral or elongate Leydig cells and connective tissue elements. The testicular volume was estimated at 0.089 ± 0.0031 cm3 with the seminiferous tubules (mean diameter = 210 ± 5.7 µm) constituting 89.4 ± 0.8% of its volume and tubulosomatic index of 0.38%. The interstitial tissue and tunica albuginea constituted 8.9 ± 0.81% and 1.7 ± 0.1% of the testis volume respectively. Conclusion: The testis exhibited general mammalian features while its vascular pattern was simple without indications of a role in testicular thermoregulation as is the case for other afrotherians. The investment of body mass in seminiferous tubules suggests a spermatogenic activity higher than expected in monogamous animals. The double caudal vena cava could be a result of retention of the left supracardinal vein to adulthood.