Background: The aim of this study was to assess the expression of estrogen receptors alpha and beta in paratesticular tissues in a group of boys with and without cryptorchidism, and evaluation of karyotypes, localization, morphology and the major length of the undescended testes.
Material/Methods: Fifty boys (1–4 years old) with unilateral cryptorchidism were evaluated. Fifty healthy boys within the same age range, with inguinal hernia, served as a control group. Measurements concerning expression of ERalpha ERbeta receptors were preformed using monoclonal mouse antibodies against human receptor alpha and beta.
Results: In the mesothelial layer, the expression of ERalpha was higher in the patients group with undescended testes and it was statistically significant (p=0.04). There was no difference in the expression of ERbeta in this layer between groups. In the stromal cell layer there was statistically significant higher expression of ERbeta (p<0.05) in the group of patients with undescended testes.
Conclusions: There was no difference between expressions of ERalpha in stromal cell layer. In the endothelial layer there was no difference in expression of ERalpha and ERbeta. In the smooth muscle layer there was no expression of ERalpha in either group. The expression of ERbeta in the smooth muscle layer was nearly identical in both groups. Undescended testes were generally found in the superficial inguinal pouch (n=46). The major lengths of the undescended testes were smaller in comparison to the testes positioned normally. In 9 of the cases the testes had different shape, and turgor deficit, and epididymides were smaller, dysplastic and separated from the testis.

Keywords: Estrogen Receptor beta - metabolism, Estrogen Receptor alpha - metabolism, Cryptorchidism - surgery, Child, Preschool, Testis - pathology