Ovarian-Specific FOXL2 Protein Expression in Testes from Patients with Complete Androgen Insensitivity Syndrome and Undescended Testes

INTRODUCTION The transcription factors Forkhead Box L2 (FOXL2) and SRY-Box Transcription Factor 9 (SOX9), among others, are required for embryonic ovarian and testicular differentiation, respectively. In patients with complete androgen insensitivity syndrome (CAIS), the testes are usually undescended and may show histological changes similar to those sometimes seen in patients with undescended testes (UDT). The aim of this study was to explore the expression of FOXL2 and SOX9 in testes from patients with CAIS and UDT.

METHODS Immunohistochemical staining with FOXL2 and SOX9 was performed on samples from 13 patients with CAIS and 20 with UDT.

RESULTS In addition to nuclear SOX9 expression in intratubular Sertoli cells, FOXL2 expression was present in stromal cells in eight of nine patients with CAIS and in one of 20 with UDT. Moreover, FOXL2 expression was found in the rete testis in three of nine samples that included this region.

CONCLUSION Expression of the ovarian-specific marker FOXL2 in regions of the testes of patients with CAIS and UDT has not previously been documented and suggests partial activation of the female pathway within these testes. Further research is needed, including FOXL2 protein expression studies in larger series, and molecular studies, e.g. transcriptome analysis, to understand the pathophysiology and clinical significance of these novel findings.