Microscopic anatomy of the skin of the Philippine carabao (Bubalus bubalis L.) and Philippine Murrah crossbred

摘要

The skin from the head, neck, dorsum, ventrum and hindlimb from five adult male Philippine carabao and Philippine Murrah crossbred were microscopically studied. The carabao skin (8.30 um) was not significantly thicker (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. Tongne-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) (P < 0.05) and thinnest in the dorsum (137.56 um) followed by those in the head (158.00 um) and hiudlimb (196.05 um). However, there was no significant difference between the epidermis of the dorsum, head and hindlimb (P > 0.05). 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, sweat 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 fibers 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 dennis of the Philippine Murrah crosshred (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.