Histological Study of Cervix Uteri in Caspian Miniature Horse

Problem statement: Uterine cervix which separates the uterus from the vagina, shows remarkable anatomical and histological differences among mammalian species. Since no cleared observations have been found in regards with the Caspian miniature horses’ cervix, the aim of the present study was to supplement this missing information which could be helpful for providing a stricter basis in detecting reproductive diseases and abnormalities in this valuable species. Approach: Cervices from 4 female adult healthy Caspian miniature horses dissected immediately after death and samples of 1cm thickness from 3 regions of cervix (endocervix, midcervix and exocervix) fixed with 10% buffered formalin. Routine histological laboratory methods were used and 6 μm paraffin slides stained with hematoxylin-eosin, Periodic acid-Schiff, Masson’s trichrome and verhoeff methods and studied under light microscope. Heights of primary, secondary and tertiary folds and mucosal glands measured with computer software. Results: The cervix comprised of primary, secondary and tertiary fold with Simple columnar epithelium in endocervix and midcervix and most cranial part of the exocervices and changes into the non keratinized stratified squamous and a transitional form with stratified squamous with columnar cells, near the vagina. Lamina propria and sub mucosa made of collagenous dense connective tissue with abundant arterial and venues plexus. Simple tubular glands observed at the base of secondary folds of endocervix and midcervix. The muscularis layer contained of inner circular and outer longitudinal smooth muscles. Serous layer covered the cervix from the outside. Conclusion: Our finding showed that the cervix uteri in Caspian miniature horse, like other horses and ruminants, are a collagenous structure, with tall longitudinal fold throughout the length. Secretion of mucus from the mucosal glands is less obvious than ruminant.