Mild experimental increase in testis and epididymis temperature in men: effects on sperm morphology according to spermatogenesis stages

Abstract

Background: A mild increase in testicular and epididymal temperatures in men, bulls and rams (pendulous scrotum) inhibits spermatogenesis and increases the percentage of sperm with an abnormal morphology.However, the stages of spermatogenesis that are most sensitive to a mild increase in testicular temperature in men are unknown. The aim of the present study was to explore the effects of a mild induced increase in testicular and epididymal temperature (i.e., testicular temperature maintained below the core body temperature) on sperm morphology in humans depending on the physiological time of spermatogenesis and epididymal transit.Methods: Five healthy volunteers were enrolled in an experimental study in which testicular and epididymal temperatures were increased by maintaining the testes in a supra-scrotal position with a specially designed underwear worn 15±1 h a day for 120 consecutive days. Semen collection was scheduled on specific days depending on spermatogenic stages and epididymal transit.Results: Sperm morphology and the multiple anomalies index (MAI) were analysed before, during and after heating. This mild induced increase in testicular and epididymal temperatures resulted in a significant rise in the percentage of morphologically abnormal spermatozoa on day 34 of heating, which remained elevated throughout the heating period and persisted until 45 days after cessation of heating. The MAI was significantly increased on day 20 throughout the heating period and persisted 45 days after cessation of heating. An increase in the percentage of anomalies in the sperm head, acrosome or tail occurred on days 34 and/or 45 of heating. Abnormal sperm morphology and MAI reverted to control values 73 days after cessation of heating.Conclusions: A mild sustained increase in testicular and epididymal temperature in man leads morphological abnormalities in spermatozoa mainly due to an impairment of spermiogenesis and meiosis.

Effect of Hesperetin Treatment on Blood Glucose Level, Spermatozoa Quality, and Spermatozoa Quantity in Alloxan-Induced Diabetic Mice

“…Increased spermatozoa abnormalities may also occur due to various disturbances, particularly during spermatogenesis at spermiogenesis (Abdelhamid et al, 2019). The shape of the spermatozoa changes based on decreased testosterone levels, on which the epididymis also depends.…”

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Comparative genomics reveals molecular mechanisms underlying health and reproduction in cryptorchid mammals

“…3 ), providing some new molecular insights into the cooling hypothesis and the training hypothesis. In scrotal mammals, the scrotum contributes to thermoregulation by the maintenance of a lower temperature than the body core, which is essential for spermatogenesis [ 41 ]. Although overheating harms normal spermatogenesis and male fertility [ 24 ] in mammals, this is not the case for natural cryptorchid mammals, especially for most ascrotal taxa with perfect homoiothermy and higher body core temperatures than the optimal condition for spermatogenesis [ 40 ], implying that an adaptive mechanism for spermatogenesis evolved in ascrotal mammals.…”