Do the cardiac glands exist? 2. The swine

Ultrastructural characterization of the epithelium that constitutes the cardiac gland epithelial 'honeycomb' in the stomach of the babirusa (Babyrousa babyrussa)

The cardiac gland region in the stomachs of eleven babirusa (Babyrousa babyrussa) from zoological collections was studied by scanning and transmission electron microscopy. An array of tightly-packed, thin-walled tubes, closely resembling a 'honeycomb' covered this region. The tubes were between twelve and sixteen cells (200 and 260 microm) in height and usually two cells (8-20 microm) in thickness. Mucus granules present in the cytoplasm of cells in the lower half of the tube were largely absent from the ad-luminal half of the tube. Instead, open goblet-like structures lined the tube, apparently giving additional strength. Bacteria were present in the lumen of each thin-walled tube and in the underlying gland pit. The evidence suggests that this large area of the babirusa stomach may be structured to form a stable, self-refreshing environment to house and multiply autochthonous commensal bacteria.