The
morphology of eight swine vallate papillae and their associated structures
was studied by using light microscopy. The results showed that the vallate
papillae and the outer wall of the trench were covered with stratified squamous
epithelium. All taste buds were located only in the lateral walls of the
papilla. The core of the papilla consisted of dense connective tissue containing
blood vessels, neurons and nerve fibers which formed a subepithelial nerve
plexus at the periphery of the core. Small ganglia and lymphoid tissue were
occasionally observed in the core. At the basal third of the papilla, many
ganglia of different sizes were found to intermingle with nerve bundles.
Very large ganglia were located underneath the papilla. All of these ganglia
were interconnected by large nerve bundles. They contained ovoid-shaped
neurons with diameter varying from 10-50 micra. These neurons were classified
according to their diameters into 4 sizes: smallest-, small-, medium-, and
large-sized neurons. There were serous, mucous and mixed glands in some
areas of the core. They were closely related to ganglia and nerve bundles.
Underneath the papilla, bundles of skeletal muscles running in various directions
intermingled with a large number of glands which were mostly serous. Several
large nerve ganglia and nerve bundles were present between these glands
and muscle bundles. Small nerve fascicles could be traced from the ganglia
to the glands. Because of the close relationship between the nervous tissues
and glands, it was suggested that the nerves conveyed parasympathetic influence
to the glands.