Mast cells, estrogens, and cryptorchidism: A histological based review

If untreated, cryptorchidism leads to age dependent decreases in germ cell number (GCN) and testicular fibrosis. The pathophysiology of this process and its long-term effects on fertility are unclear. Mast cells are intricately involved in inflammation and fibrosis in a variety of organ systems. Their secretory products have mitogenic effects on fibroblasts and promote collagen deposition. Mast cell activation and migration are under the influence of estrogens and this interaction has been demonstrated in the testes in several animal models. Models of cryptorchidism have shown increased estrogen levels and expression of estrogen receptors in undescended testes compared to controls. Mast cell numbers have positively correlated with testicular fibrosis in human studies and decreased spermatogenesis as well. We found no human studies of mast cells in cryptorchid testes. However several animal models have investigated the effect of estrogens on mast cells and spermatogenesis in undescended testes. In this review we examine the possible links between estrogens, mast cells, and testicular fibrosis in cryptorchidism, focusing on histological studies.