Page 200 - Veterinary Histology of Domestic Mammals and Birds, 5th Edition
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182  Veterinary Histology of Domestic Mammals and Birds



                   Cheek (bucca)                                  Palate (palatum)
       VetBooks.ir  The cheeks (Figure 10.4) are similar in structure to the lips,  The palate comprises the hard palate (palatum durum),
                                                                  which covers the bones of the roof of the oral cavity, and
                   comprising the following layers:
                                                                  the soft palate (palatum molle, velum palatinum), which
                     ·  outer skin layer,                         extends towards the pharynx.
                     ·  middle muscle layer and
                     ·  inner mucosal layer.
                                                                  Hard palate (palatum durum)
                   Unlike the lips, the cheeks are covered externally by hair.   The lining of the hard palate comprises:
                   The middle layer consists of the buccal musculature. The
                   inner wall is composed of non-glandular mucosa lined by   ·  keratinised stratified squamous epithelium that
                   stratified squamous epithelium. In ruminants, buccal papil-  interdigitates with collagen-rich subepithelial con-
                   lae (papillae conicae buccales) are present on the surface   nective tissue (papillation) and
                   of the mucosa.                                   ·  deeper connective tissue containing small vessels
                      The tela submucosa contains extensive aggregates of   and a large venous plexus, as well as numerous
                   buccal glands (glandulae buccales) that distribute their   fibrocytes,  lymphocytes and macrophages (fuses
                   secretory product to the vestibulum oris through short   with subepithelial connective tissue to form a
                   ducts. The buccal glands are minor salivary glands. They   propria-submucosa).
                   extend deep into the buccal musculature, which aids in
                   expressing the secretory product during chewing. The   The mucosa of the hard palate is lined by stratified squa-
                   extent of the buccal glands and the composition of their   mous epithelium. It is a mostly non-glandular, tough
                   secretions varies with species. Morphologically, they   layer of tissue that is tightly bound to the periosteum of
                   are classified as compound tubulo-acinar glands. Based   the underlying bone. The mucosa exhibits  transverse
                   on their secretory product, buccal glands are divided    ridges (rugae palatinae) that vary in number and promi-
                   into:                                          nence, depending upon species. The surface of the ridges
                                                                  is reinforced by thick sheets of non-glandular, heavily
                     ·  serous glands: ventral buccal glands of cattle,  keratinised epithelium. Isolated mixed glands (glandu-
                     ·  mucous glands: middle and dorsal buccal glands   lae parapapillares) occur between the caudal ridges in
                       of cattle, ventral buccal glands of sheep, goats and   ruminants and in the dog, and more rostrally in the pig.
                       carnivores and                             The taut lamina propria blends without obvious demarca-
                     ·  mixed glands: buccal glands of horses and pigs.  tion with the tela submucosa, through which it is tightly
                                                                  fused to the periosteum. In carnivores and (particularly)
                                                                  in ungulates, the propria-submucosa contains an extensive
                                                                  branching venous network. In ruminants, the mucosa is




























                   10.4  Cross-section of the cheek (dog). The outer surface is lined by skin in which numerous hairs and glands are
                   present. A layer of muscle lies between the skin and the non-glandular mucosa of the oral cavity. Haematoxylin
                   and eosin stain (x26).









       Vet Histology.indb   182                                                                                  16/07/2019   15:00
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