A study of the functional anatomy of the bovine cervix with special reference to the epithelium, mucus secretion and sperm transport
Anatomical features of bovine cervical epithelium were investigated with respect to mucus secretion and sperm transport. Techniques included: 1. Surface staining of fixed tissue blocks in Harris' hematoxylin followed by steriomicroscopic examination, 2. Model construction from serial sections using both computer-aided and plexiglas assembly of epithelial tracings, 3. Histochemical investigation using five follicular phase animals (four bred naturally 8 to 12-h before slaughter) and three luteal phase animals. Cross-sections of two samples from each quarter cervix were stained with (1) Alcian blue (AB) at pH 1.0 (sulfomucins) and at pH 2.5 (sialomucins and sulfomucins); (2) periodic acid Schiff (PAS) (neutral mucins) and AB (pH 2.5); (4) high iron diamine (HID) (neutral and sulfomucins) with AB (pH 2.5). Additional samples were processed for ultrastructural examination. The mucosa was characterized by longitudinal primary and secondary folds which maintained continuity throughout the cervix, with numerous tertiary shallow ’grooves’ apparent on all epithelial surfaces. No evidence was found suggesting blind-ending glands or crypts. Staining results in follicular animals indicated a predominance of neutral and sulfated mucins in apical areas with secreted mucins extending as sheets from these areas toward the central canal. In basal areas (within grooves) sialomucin production was predominant with secreted mucins evident within grooves and between neutral mucin layers. In luteal phase animals, sulfated and neutral mucins were abundant in both basal and apical areas, while sialomucin production was decreased. Using light and transmission electron microscopy, spermatozoa observed within the cervix appeared unidirectionally opposed to ciliary beat. Suggested privileged paths for the transport of viable spermatozoa are within grooves, where sialomucins were most predominant.