Abstract
The purpose of this study was to describe the morphometric parameters of the ovary and corpus luteum (CL) of native mares in Colombia. Fifty ovaries from adult mares were used. All animals were clinically healthy. The tissues were collected after slaughter and immediately fixed in buffered formalin. The large and small diameters of the ovary were weighted and measured. A longitudinal incision was made in order to observe organ parenchyma. The CL was removed and its weight and diameter were recorded. Data were analyzed with descriptive statistics, and the degree of association between the variables was calculated through a simple regression model. When required, data were transformed with natural base logarithm. The large diameter of the ovary ranged from 2 to 6.2 cm. The diameter of the CL ranged from 1.1 to 3.6 cm. A linear relationship was found between the weight and diameter of the ovary (R<sup>2</sup> = 0.41; p < 0.01) and between the weight and diameter of the CL (R<sup>2</sup> = 0.48; p < 0.01). On the other hand, although the relationship between the weight of the ovary and corpus luteum is linear, the determination coefficient was very low. Luteal and ovarian morphology of native mares in Colombia has similar characteristics to those reported in literature for other light breed mares. The values reported herein could be the starting point to establish reference values for clinical utility.