Negative feedback in spermatogenesis is by

Inhibin is One of several proteins that paicipate in differentiation and growth. Two glycoproteins, inhibin A and inhibin B, are secreted by Seoli cells in the testis and granulosa cells in the ovary, inhibiting FSH secretion by direct action on the pituitary.Ref: Ganong&;s review of medical physiology;24th edition; page no:-427