THE PHILIPPINE WATER BUFFALO

(P>0.05) from that of the Philippine Murrah crossbred (9.13
um). Regardless of breed, the skin was significantly thickest
in the neck (11.80 um) followed by those in the ventrum
(8.90 um), dorsum (8.11 um) and head (7.94 um). The skin
was thinnest in the hindlimb (6.82 um) followed by those in
the dorsum and head (7.94 um). In both breeds, the
epidermis was composed of only four layers: stratum
corneum, stratum granulosum, stratum spinosum, and
stratum basale. The stratum lucidum was absent in all
areas examined. The shape, size and number of the
epidermal ridges or pegs were extremely variable in both
breeds. Tongue-shaped, pointed, wide and branching
epidermal ridges were observed. Although the epidermis
was thicker in the carabao (197.23 um) than in the Philippine
Murrah crossbred (171.40 um), their difference was not
statistically significant (P>0.05). Regardless of breed, the
epidermis was thickest in the neck (211.95 um) and ventrum
(218.00 um) (P0.05). The dermis in both breeds was made up of two
indistinctly separable layers: the superficial papillary layer
and the deep reticular layer. Collagen, elastic and reticular
connective tissue fibers, blood vessels, hair follicles and
their sebaceous glands, nerve fibers and smooth muscle
fibers were found in the dermis. The collagenous fibers
were finer in the papillary layer than in the reticular layer. In
the papillary layer the more slender collagenous fiber were
more compact and were oriented parallel to the skin surface.
In the reticular layer, these were loosely arranged, some
occurred in bundles, and ran in various directions. The
collagenous fibers were more regularly arranged in the
Philippine Murrah crossbred than in the carabao. Hair
follicles were few and occurred singly. They were
particularly numerous in the head of the Philippine Murrah
crossbred and in the hindlimb of the Philippine carabao.
The sebaceous glands were large and were attached near
the base of hair follicles. Some hair follicles lacked
sebaceous glands. Two types of apocrine sweat glands
were seen in both breeds: tubular and saccular, with the
former being more numerous than the latter. There were
more sweat glands in the Philippine Murrah crossbred
than in the Philippine carabao. The dermis of the Philippine
Murrah crossbred (10740.0 um) was significantly thicker
than that of the Philippine carabao (6136.0 um). This study
disproved earlier reports that carabaos lack sweat glands.
Keywords: Bubalus bubalus, hair follicles, skin thickness,
sebaceous glands, apocrine glands, Philippine carabao.
*The Philippine Journal of Veterinary and Animal Sciences.
25(2): 16-37, 1999.
ANATOMY
A-12
HISTOLOGY OF THE SKIN IN SOME SPECIALIZED
REGIONS OF THE PHILIPPINE CARABAO (Bubalus
bubalis)*
C. L. Castillo, Student
Skin from the upper and lower eyelids, muzzle, external
ear, mammary area, prepuce, scrotum and interdigital space
of two to six years old Philippine carabaos were studied
histologically. The epidermis from these regions was lined
by a stratified squamous epithelium, which consisted of
four layers: the stratum corneum, stratum granulosum,
stratum spinosum and stratum basale. The stratum lucidum
was absent in all the regions examined. Condensation of
melanin was observed more on the basal layer of the
eyelids, muzzle and external ear than on the mammary
area, prepuce, scrotum and interdigital space. The dermis
in all the regions was indistinctly divided into superficial
papillary and deep reticular layers. Collagen, elastic and
reticular fibers were present in both layers of the dermis. In
the papillary layer the collagenous fibers occurred in fine
bundles and ran mostly parallel to the skin surface. In the
reticular layer the collagen fibers formed the bulk of the
layer and were large, coarse and dense. They ran mostly
parallel to the skin surface. In general, the basic architecture
of the integument was similar in all the animals examined.
Differences existed, however, in the thickness of the
epidermis and the dermis in various regions of the body.
The upper and lower eyelids were characterized by the
tarsal glands which were modified sebaceous glands. The
tarsal glands were larger and well-developed in the upper
eyelid and the hair follicles were thicker and numerous. In
the lower eyelid, the tarsal glands were smaller and less
developed and the hair follicles were smaller and less
numerous. The sweat glands were both tubular and saccular
apocrine types and the branched sebaceous glands were
large. Striated muscle fibers of the orbicularis oculi and
levator palpebrae superioris were found in both the upper
and lower eyelids whereas only the orbicularis oculi was
found in the lower eyelid. The muzzle epidermis was
highly cornified and the thickest of all body areas examined.
The stratum lucidum was absent. It is devoid of hair follicles
and had tubular merocrine glands known as muzzle or
nasolabial glands with characteristic of salivary glands.
The external ear was covered by thin skin. However, the
epidermis was thicker in the outer convex surface than in
the inner concave surface. The epidermal pegs on the
other hand, were more complex in the inner surface than in
the outer surface. The hair follicles were more numerous in
the convex surface. The sebaceous glands were highly
developed and lobulated. The external ear contains
5