Role of laminin and collagen chains in human spermatogenesis - Insights from studies in rodents and scRNA-Seq transcriptome profiling.

Studies have demonstrated that biologically active fragments are generated from the basement membrane and the Sertoli cell-spermatid adhesion site known as apical ectoplasmic specialization (apical ES, a testis-specific actin-based anchoring junction) in the rat testis. These bioactive fragments or peptides are produced locally across the seminiferous epithelium through proteolytic cleavage of constituent proteins at the basement membrane and the apical ES. Studies have shown that they are being used to modulate and coordinate cellular functions across the seminiferous epithelium during different stages of the epithelial cycle of spermatogenesis. In this review, we briefly summarize recent findings based on studies using rat testes as a study model regarding the role of these bioactive peptides that serve as a local regulatory network to support spermatogenesis. We also used scRNA-Seq transcriptome datasets in the public domain for OA (obstructive azoospermia) and NAO (non-obstructive azoospermia) human testes versus testes from normal men for analysis in this review. It was shown that there are differential expression of different collagen chains and laminin chains in these testes, suggesting the possibility of a similar local regulatory network in the human testis to support spermatogenesis, and the possible disruption of such network in men is associated with OA and/or NOA.