Study of the functional anatomy of bovine cervical mucosa with special reference to mucus secretion and sperm transport

Abstract

The bovine cervical mucosa was investigated with respect to structure, mucus secretory pattern, and sperm transport. Structural investigation included stereomicroscopic examination of surface-stained tissue blocks and graphic reconstruction of serial sections by using both computer-generated and Plexiglas models. Histochemistry of the mucosa was evaluated in follicular- and luteal-phase animals. Alcian blue, periodic acid Schiff, and high-iron diamine were utilized to distinguish sialomucins, sulfomucins, and neutral mucins. Location and orientation of cervical sperm in follicular phase animals were evaluated 12 h postmating by using light and electron microscopy. Cervical mucosa was characterized by longitudinal primary folds, most of which maintained continuity throughout the cervix. Superimposed on these were secondary folds which varied in length and depth. Abundant, shallow, uniformly spaced, and parallel longitudinal "grooves" covered all surfaces. Grooves had greater continuity in regions distal, as opposed to proximal, to the cervical canal. Blind-ending glands or crypts were not apparent. Follicular-stage cervices exhibited a pronounced sialomucin production in basal areas within grooves while neutral and sulfomucins were predominant in apical areas. In luteal-phase animals, basal sialomucin production was markedly decreased while sulfated and neutral mucins remained abundant. Numerous cranially oriented spermatozoa were observed within the shallow grooves of cervical folds (sialomucin-rich areas) in mated animals and were unidirectionally opposed to ciliary beat. It appeared that privileged paths for transport of viable spermatozoa may originate in the fornix vagina, extend through longitudinal primary folds at the external os, and progress to the uterus within continuous sialomucin-rich channels which are associated with basal areas of the shallow grooves, distal to the cervical canal.