Update on human sperm anatomy:new perspectives in the treatment of human male fertilità

Mammalian ejaculated spermatozoa have been studied always with great interestbecause their function in fertilization and their peculiarities as unique cellular type.Significant strides have been made, but the signalling pathways that govern theirphysiology as well as their ultrastructural molecular set up is at the beginning of theknowledge. Recently, it has been shown that sperm expresses some nuclearreceptors and their classical ligands, discovering that sperm has the ability tomodulate its functionalities according to the physiological status, independently bysystemic regulation. The spermatozoon leaves the testis, moves through the femalegenital tract in the host body of the opposite gender, so it needs to be autonomous.Sperm resembles a b-pancreatic cell as it secretes insulin, an adipocyte cell as itsecretes leptin and expresses the PPARgamma, showing an autocrine regulation onglucose and lipid metabolism. Sperm contains the aromatase, the estrogen and theandrogen receptors regulating through an autocrine short loop both its acquisition offertilizing ability and survival. Intriguingly, it also possesses the VD3/VDR systemthat in turn is able to modulate estrogen biosynthesis, linking different steps in spermphysiology. The main line of this review is a reflection about the current researchesin the human sperm molecular status that highlights a new system of the response tohormones as well as regulatory pathways controlling sperm cell fate and its basicfunctions.