Cutaneous eccrine glands of the foot pads of the rock hyrax (Procavia capensis, Hyracoidea, mammalia)

In order to find correlations between skin gland morphology and
specific ethological features, the cutaneous glands of the foot
pads of Procavia capensis were studied by histological and various
histochemical methods and by electron microscopy. In the foot pads,
abundant specific eccrine skin glands occur, which consist of
coiled tubular secretory portions and coiled ducts. The wall of the
secretory part is composed of cuboidal glandular cells and
myoepithelial cells. Among the glandular cells two types occur:
clear and dark cells. Clear cells have numerous mitochondria and
form a basal labyrinth, indicating fluid transport. Dark cells,
which stain strongly with periodic acid-Schiff, contain a highly
developed perinuclear Golgi apparatus, large amounts of rough
endoplasmic reticulum and many secretory granules indicating
production of glycoproteins. Cytokeratin (CK) 19 was found in
secretory compartments and ducts, CK14 only in duct cells. Single
cells of the secretory coils and ducts may be stained with
antibodies against antimicrobial peptides. Some glandular cells
contain proliferating cell nuclear antigen-positive nuclei
especially in the ducts indicating an increased cell proliferation.
Terminal transferase (TdT)-mediated d-UTP nick-end
labeling-positive nuclei can be detected predominantly in the
secretory coils and rarely in the transitional portions between
ducts and end pieces. We suppose that proliferating cells migrate
from the ducts to the secretory coils. The secretory product of the
eccrine cutaneous glands seems to improve the traction between the
foot pads of these animals and the steep and smooth rock formations
among which they live.