Effects of age on histological parameters of the sweat glands of Nellore cattle

Resumo

The sweat glands are important in thermoregulation of cattle in a warm environment as they help dissipate heat
through evaporation. Studies on gland histology are important to define its secretion potential and the capacity of
perspiration and heat removal. The objective of this study was to determine, by histomorphometry, glandular
epithelium height, the depth of the gland, length of the glandular portion and number of glands per cm2 of the sweat
glands of the three age groups of Nellore cattle. Thirty females were used in this study. They were equally divided
into calves, heifers and cows. Histological sections were obtained and analyzed by digital images in Trinocular
BX40 Olympus microscope coupled to an Oly – 200 camera, connected to a computer. The images were obtained
with microscope with 2x, 4x, 10x and 40x magnification objectives. The measurements were performed using HL
Image 97 program. The height of glandular epithelium, depth of the glands, length and density of the glandular
portion per cm2
, were all analyzed. The calves showed greater height of the glandular epithelium than heifers (P =
0.0024), and cows (P = 0.0191). The depth of the gland was not influenced by age. Cows had higher length of
secretory portion than heifers (P = 0.0379) and calves (P = 0.0077). Heifers had a greater number of sweat glands
per cm2 of skin than cows (P = 0.023). In cattle, the height of glandular epithelium and the density decreases as
animals get older. On the other hand, the length of the secretor portion increases but with no changes in the depth of
the sweat glands.