Differential expression of placental (P)‐cadherin in sertoli cells and peritubular myoid cells during postnatal development of the mouse testis

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 β‐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 during the first week of development, but began to express P‐cadherin on postnatal day 8 and continued expression in adulthood. β‐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 β‐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 β‐catenin and the development of a mature network of actin filaments and is consistent with a role in intercellular adhesion and junction formation. © 1996 Wiley‐Liss, Inc.