The anatomy of the sheep cervix and its influence on the transcervical passage of an inseminating pipette into the uterine lumen

The maximum depth of cervical penetration was affected by cervical grade (series A: P = 0.021; series B: P = 0.037) and the stage of the oestrous cycle (P = 0.008). Grade 1 cervices were more penetrable than grade 2, with grade 3 the least penetrable and non-luteal cervices could be penetrated further than luteal cervices. The distribution of os types differed with age, with rose types more common in adult ewes, and papilla os types more common in ewe lambs. These results indicate that the depth of cervical penetration is affected by the anatomy of the cervical lumen. Cervices with a less convoluted lumen (grade 1) were more penetrable. Non-luteal cervices are likely to have higher oestradiol concentrations than luteal, stimulating cervical relaxation and enabling deeper penetration. The difference in os types with age may be contributable to a morphological alteration at parturition.