Anatomical and histological characterization of the cervix in Santa Inês hair ewes

The aim of the present study was to describe the morphology of the cervix in Santa Ines ewes. One hundred cervices were collected from females of different ages (12 to 48 months). Five types of cervical os were observed: duck-bill, flap, rosette, papilla and spiral, with duck-bill being the most predominant type (51%) overall. The average cervix length was 4.68 cm (range of 3 to 7 cm). Shorter cervices (P < 0.05) were observed in younger females (12-18 months). The number of rings was on average 5.68 (range 3 to 8). There was a positive correlation between cervical length and animal age (r = 0.22; P < 0.0001) and between cervical length and number of rings (r = 0.21; P < 0.0001). Cervical rings were generally funnel-shaped and the mean internal diameter of the rings was 2.98 mm. The average number of rings with fornix was 5.17. The presence of fornix in the first three rings was higher than in the subsequent rings, gradually decreasing until the seventh ring. The internal shape of the cervix resembled two inverted cones, being wider at both ends and narrower in the middle. Differences in the internal characteristics of the cervical canal (length, diameter, number of rings, and number of fornices) were observed only between some of the cervical os shapes, and the success of the cervical passage cannot be predicted by the determination of the cervical os shape. Some anatomical features of the cervical canal in Santa Inês ewes differ from those reported for other sheep breeds, showing that information obtained can be useful to define the characteristics of devices to be used for achieving successful cervical penetration during insemination of Santa Inês ewes.