Italiano Inhibin is a heterodimeric protein hormone secreted by Sertoli cells in the testis that inhibits the production of follicle-stimulating hormone (or FSH) that indirectly affects the development of male gametes. In granular ovarian cells, however, it participates in the regulation of the menstrual cycle.
Inhibin-A consists of an alpha subunit and a beta-A subunit while Inibina-B consists of an alpha subunit and a beta-B subunit.
In the circle, both dimeric molecules of Inibin A and B and their free subunits can be found: only the first are biologically active ones.
Inhibin A, found only in woman with the arrival of menarca, is secreted by the luteum body, and has 
negative feedback on pituitary production of FSH: inhibin A is therefore measurable in the late luteal phase of the menstrual cycle; inhibin B, secreted in both man and woman, has maturative action on the gonade produced by the Sertoli cells (man) and the cells of the granulosa (woman): man controls spermatogenesis with negative feedback on the FSH , while in women the ability to mature a follicle in the ovary.In both cases, inhibin B is considered as follicular reserve marker (in woman) and spermatogenicity in humans: in fact, if 
Inhibins B did not take feedback-negative action on pituitary FSH production, neither maturation of follicles nor spermatogenesis would be properly controlled because the FSH itself has a positive feedback.
The production of inibin B occurs from 18 to 24 months of age, following the “mini puberty”, a typical event of the first months of life with spikes of sex-like sex hormones such as puberty that guarantee the maturation of fetal gametes in post-natal gametes, with ripening and selection of female gametes and amplification of male ones.
Inibina A Ref. BXE0615A 96 test
Inibina B Ref. BXE0618A 96 test