Modern concepts of the structural bases for the reparative regeneration of the mammalian and human testis

Abstract

Modern concepts of the structural bases of the reparative regeneration of the mammalian and human testis are discussed in this article, based on published data and our own findings. The significance of the rete testis as a regeneration zone is discussed as well as the use of its potentials in clinical andrology. Key Words: mammalian and human testis; rete testisThe dissertation of A. A. Maksimov was one of the first studies of regeneration of the testis [9]. Although some premises underlying this work proved to be controversial, this excellent investigation was the basis for many studies carried out by S. S. Raitsina. In 1985, summing up the studies of many years, this scientist, focusing on spermatogenesis as a biological phenomenon, introduced the concept of "reproductive strategy of spermatogenesis," which she interpreted as a set of adaptations or mechanisms providing for the greatest reproductive success under certain environmental condititions [16]. The totality of mechanisms underlying the protection of the genome in developing sex cells was In-st considered as one of the forms of reproductive strategy.Cytoplasmic determinants of primary sex cells (PSC), their early individuation and subsequent migration to the germinal gonads, symbiotic relationships with somatic ceils of the gonad, the blood-testis barrier (BTB), autoantigens of male sex cells and autoimmune processes resulting in the Research Institute of Human Morphology, Russian Academy of Medical Sciences,-International Institute of Biological Medicine, Moscow destruction of the seminiferous tubules, as well as their successive regeneration due to the rete testis epithelium and to the PSC preserved in it from the period of embryogeny form the structural basis of the adaptive reactions guaranteeing the participation of cells with an unchanged and completely sound genome in fertilization. Is the destruction of the seminiferous tubules the regular reaction of the testis affected by damaging factors? The destruction of the semirtiferous tubules was described for the ftrst time by Maksimov [9] after traumatic damage of the testis, namely after puncture with a hot needle or a small wedge-shaped resection of the tissue in rabbits. He found that the destructive processes were not restricted to the damaged region, but "rapidly occupied without any visible cause the entire organ," eventually resulting in atrophy of the testis. The damage to the seminiferous tubules and concomitant loss of the specitic structure of the testis were accompanied by a drop in the weight of the organ. These observations were further confirmed by the studies of numerous authorities [2][3][4]12,13,36].The autoimmune nature of the posttraumatic destruction of the seminiferous tubules is now considered as proven [4,15,48,49].

Responses of Spermatogenous Tissue and Mechanisms of Their Development Upon Cytostatic Exposure

“…In mature seminiferous tubules, these cells lose their ability to divide. It is assumed that reparative regeneration of structural components of the testis occurs only via formation of new immature tubules from the regenerative zone of the testis, rete testis [6], where Sertoli cells are able to divide, which, in turn, does not restrict SSC proliferation.…”