Histomorphometric comparison of left and right oviduct structure from alpaca (Vicugna pacos).

Alpacas are species of induced ovulation and with foetal development only in the left uterine horn (98%). The histoarchitecture of the oviductal regions determine a spatio-temporal interaction between the gametes/embryos and the oviduct. This study compares the morphometric changes of the left and right oviducts in alpaca during the follicular phase. Five oviducts (n = 05), from adult alpacas with dominant follicle in the right ovary were recovered, dissected, and processed by histological technique with H&E and PAS stain for measurement of morphometric parameters and cell characteristics, respectively. Also, a 3D image reconstruction was performed (by reconstruct software). Resin moulds (polyurethane PU4ii) were applied for visualization of oviductal lumen. The multivariable data of parameters were analysed with ANOVA and principal component analysis (PCA). The histomorphometric parameters of left and right oviducts did not show statistically significant differences (p ≥ 0.05), although PCA showed morphometric differences between regions of the oviduct. No differences were observed between the 3D reconstruction of the left and right oviducts, as well as in the luminal spaces examined in the resin moulds. In conclusion, the histomorphometry of the oviduct is not affected by its location on either the left or right side; therefore, it cannot explain why 98% of foetuses implant in the left uterus.