Chapter 314 - Cell–Cell Signaling in the Testis and Ovary

Michael K. Skinner; Eric E. Nilsson; Ramji K. Bhandari

doi:10.1016/B978-0-12-374145-5.00314-4

This chapter focuses on the regulatory signals that mediate cellcell interactions in the testis and ovary. Transforming growth factor-α (TGFα) is an epidermal growth factor (EGF) superfamily member, and is produced by Sertoli, peritubular, and Leydig cells. TGFα can act as a growth stimulator on all the major cell types in the testis. Platelet-derived growth factor (PDGF) is produced by Sertoli cells and influences peritubular cells and Leydig cells. Although PDGF in the adult may also be produced by the Leydig cell, it appears to be a factor produced within the seminiferous tubules that acts on adjacent peritubular and Leydig cells. Another factor that is only produced by Sertoli cells is stem cell factor (SCF)/kit ligand (KL), which has a direct role in regulating spermatogonial cell proliferation. Granulosa cells are the primary cell type in the ovary that provides the physical support and microenvironment required for the developing oocyte. Granulosa cells are actively differentiating cells with several distinct populations. Alteration and progression of cellular differentiation is required during folliculogenesis from the arrested primordial stage of development through ovulation to the luteal stage of development. Estrogen biosynthesis is controlled by the enzyme aromatase, which requires androgen produced by the theca cells as a substrate. The granulosa cells differentiate and estrogen biosynthesis increases with the follicle development. Another important cell type in the ovary is the ovarian theca cell. These are differentiated stromal cells that surround the follicle and are termed as theca interstitial cells. The inner layer of cells, the theca interna, has a basement membrane separating it from the outermost layer of mural granulosa cells. One of the major functions of theca cells in species such as cattle, humans, and rodents is the secretion of androgens, which are used by granulosa cells to produce estrogen.

Chapter 314 - Cell–Cell Signaling in the Testis and Ovary

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