The testicular form of angiotensin converting enzyme as a marker for human sperm quality assessment

Abstract

Introduction: Spermatozoa are rapidly changing cellular structures that are highly dependent on their interaction with the environment. These interactions cause fundamental changes in the spermatozoa’s cells and membrane. All physiological changes that a spermatozoon goes through are required for fertilization. One of the proteins that are essential for the physiological processes in the spermatozoon membrane is the testicular angiotensin-converting enzyme (tACE). In human ejaculated spermatozoa, tACE is found on sperm plasma membrane in the head, neck, and midpiece of the tail having an active role in the capacitation and acrosome reaction. Aim: Immuno-histochemical and fluorescent testing of the testicular isoform of the angiotensin-converting enzyme during spermiogenesis and acrosome membrane of spermatozoa. Materials and methods: Testis biopsies from infertile males have used immunohistochemical testing and fixed spermatozoa for the immunofluorescence assay of tACE. Results: The immunohistochemical test showed tACE expression during spermiogenesis and its participation in the stages of spermatid differentiation in the testis. The immunofluorescent test follows the manifestation of tACE in untreated, capacitated, and acrosome-reacting spermatozoa. In the process of capacitation and acrosome reaction, we found considerable dynamics accompanied by a change in the expression of tACE on the sperm membrane. Conclusions: tACE expression during spermiogenesis and its visualization in the acrosome region confirms the active role of the enzyme in the processes of maturation, capacitation, and acrosome reaction, which determines the enzyme as a reliable marker for the selection of quality spermatozoa in assisted reproduction.