Endometrial Collagen in Woolly Monkey (Lagothrix l. poeppiggi) and the Uakari (Cacajao calvus)

Pereira T.H.D.S.; Monteiro F.O.B.; Júnior F.A.F.X.; de Carvalho I.O.; Evangelista J.S.A.M.; Lima A.K.F.; Mayor P. · Journal of Medical Primatology (2026) · DOI: 10.1111/jmp.70055

Resumen

Introduction: This study microscopically characterizes collagen changes and their relationship with endometrial architecture in two Neotropical primates. Methods: Uterine fragments from six Lagothrix l. poeppigii and six Cacajao calvus in different reproductive phases were histologically processed using Picrosirius Red staining. Results: In the functional layer, collagen was highest in the early proliferative phase (5.19% ± 2.53%; p < 0.001), whereas the basal layer had the lowest percentage (5.85% ± 4.69%; p < 0.01). Type I collagen predominated, while type III was less expressed. Type I collagen varied significantly between proliferative phases (p < 0.001). The basal layer exhibited more fibers in the secretory phase (14.03% ± 8.50%; p < 0.001). Type III collagen peaked in the functional layer (0.41% ± 0.17%; p < 0.001) and basal layer (0.69% ± 0.46%; p < 0.05). Conclusion: Picrosirius Red staining with polarized light effectively highlights collagen organization, aiding reproductive phase characterization in Neotropical primates.