Background: In previous work, RNA transcripts for placental (P)-cadherin, a calcium-dependent cell adhesion molecule, were identified in the rat testis during the first 4 weeks of postnatal development. However, the cells in the testis responsible for P-cadherin expression have not yet been identified.
Methods: We used conventional epifluorescence microscopy to examine P-cadherin immunoreactivity in cryostat sections of mouse testis and scanning laser confocal microscopy to localize P-cadherin and beta-catenin in wholemount preparations of mouse seminiferous tubules. We used fluorescent phalloidin to identify actin filaments.
Results: Sertoli cells expressed P-cadherin on postnatal days 1, 3, and 8, but not on any day thereafter. In contrast, peritubular cells did not express P-cadherin on postnatal day 8 and continued expression in adulthood. beta-Catenin was localized near contact areas between peritubular cells on postnatal days 12 and 15. A mature pattern of actin filament organization in peritubular cells appeared on day 15 and coincided with the uniform appearance of P-cadherin and beta-catenin near areas of contact between adjacent peritubular cells.
Conclusions: During postnatal development of the testis, the earlier expression of P-cadherin by Sertoli cells is replaced by the subsequent expression of P-cadherin by peritubular cells. The expression of P-cadherin in peritubular cells is correlated temporally with the expression of beta-catenin and the development of a mature network of actin filaments and is consistent with a role in intercellular adhesion and junction formation.