Influence of age and cervical grade on anatomy, morphology and depth of cervical penetration in Sanjabi ewes

The structure of the sheep cervix limits the application of reproductive biotechnologies such as embryo transfer and artificial insemination. The aim of this study was to determine differences in cervical anatomy and morphology between Sanjabi lambs and ewes, and the relationship between cervical anatomy and cervical penetration in ewes. Four hundred and sixty eight postmortum cervices belonging to six different age groups were used. The cervical external os was classified as slit, papilla, duckbill, flap or rose. Cervical folds were counted and the degree of completeness and interdigitations of the folds recorded as one of three grades 1, 2, and 3 cervices. There were significant differences (P < 0.05) in cervical length and number of folds amongst ewes of various ages. The cervix of the ewes at ages < 6 months and 6 -12 months, and grade 3 cervices were shorter and narrower, with more cervical folds. Cervical penetration differed according to the cervical grade, being deeper in grade 1 (simpler cervix) than in grade 3 cervices (more complex cervices). Cervical penetration was correlated positively with the length and width of the cervix, (r = 0.93 and r = 0.88; P < 0.01 respectively) and negatively with the number of cervical folds (r = - 0.61; P < 0.01). At ages < 6 and 6 - 12 months the distance between cervical folds was (P < 0.05) shorter than at another ages. At ages < 6   and 6 - 12 months the flap os, at ages 1 - 2 and 2 - 3 years the papilla os, at ages 3 - 4 years the duckbill os and at ages > 4 years the rose os were observed more frequently. These results showed that with advancing ewe age, the cervix tended to be larger and less complex, with a smaller number of cervical folds and this noticeably improved cervical penetration. Thus a practical point of view would favor the application of reproductive biotechnologies at ages > 4 years, even in 3-4 age years, because the cervix is more penetrable to catheter after 3 - 4 years of age.

Keywords:

cervix , Sanjabi ewes , cervical penetration , cervical folds , age