The macro-anatomical organization of the mare ovary differs from other mammalians since the parenchymal zone is positioned inside the ovary. The parenchymal zone is bell-shaped and it is surrounded by the vascular zone. Regarding body size, the ovary of mares is bigger compared to that of other species, such as cows. The objective of this study was to verify the special structure of a mare ovary by obtaining transparent slices using the E12 method. A number of 14 mare ovaries were collected and 2 of them were selected through palpation based on the presence of functional structures (follicles and a corpus luteum). These specimens were plastinated using the E12 method and cut into 2-mm transparent slices. A mature follicle was found in one of the ovaries, and the stigma could also be seen. Several follicles and a corpus luteum were found on the slices of the other ovary. These slices can be used as a teaching/learning resource by clinicians and students since the structures observed are similar to those obtained using ultrasound.