ALBERT

Description: 1. Spindle-shaped myoepithelial cells with longitudinal myofibrils have been demonstrated in the sweat glands of Ayrshire and Zebu cattle.2. The cells in both breeds are similar in structure, location and arrangement.3. Under the polarizing microscope they are birefringent as is characteristic of other fibrillar structures.

Description: 1. A method of perfusing the skin of the flanks and the backs of Ayrshire calves and embryos with indian ink is described.2. The distribution of blood vessels in the perfused skins has been studied.3. Three plexuses of blood vessels have been observed in the skins. The first lies below the corium; the second is at a level between that of the ‘sweat glands’ and the sebaceous glands; and the third extends from beneath the epidermis to above the second plexus and is a deep network of many fine blood vessels.4. The presence of venae comites in the skin is discussed.5. The ‘sweat glands’ appear to have a very poor blood supply, while the hair follicles and papillae are richly supplied.6. Both the ‘sweat glands’ and the hair follicles are supplied with blood from the second plexus.7. The vessels of the third plexus appear to enmesh the individual hair follicles at different levels.8. Blood vessels supplying the skin in the back and flanks of the animals originate from the intercostal arteries and so pass through the heat generating intercostal muscles.

Description: 1. Histochemical tests have been applied to the socalled sweat glands and their secretions of Zebu and Ayrshire cattle, the former to only a limited extent.2. For skin specimens of Ayrshire cattle positive reactions were obtained for ribonucleoprotein, arginine and alkaline phosphatase. Negative reactions were obtained for desoxyribonucleoprotein and acid glycerophosphatase.3. Neither the sweat glands of Ayrshire cattle nor those of Zebu cattle gave positive reactions for fats, lipids or cholesterol and its esters, although these were all present in the sebaceous glands of both breeds. Detectable amounts of phospholipid were not found in the sweat glands of the Ayrshire cattle and their secretions.4. The chemical composition of the secretion of bovine sweat glands differs markedly from that of human eccrine or apocrine sweat glands in not containing detectable amounts of glycogen, lipids and associated compounds or iron.

Description: 1. An investigation has been made of the structure, distribution and dimensions of the so-called sweat glands in twenty-one different body regions of each of five 3- to 4-year-old Ayrshire cows, and incidental studies have been made on calves and embryos.2. It has been observed that in all those regions each hair follicle is accompanied by an arrector pili muscle, a sweat gland and a sebaceous gland. This combination has been designated a ‘hair follicle unit’.3. In the skin of embryos the sweat gland appears as a single unbranched tube and in the skin of calves and cows it is a bag-shaped gland with a long slender duct which opens on the skin surface as a funnel-shaped outlet.4. The gland is composed of two layers of cells, an outer myoepithelium and inner glandular epi thelium.5. What may be successive stages in the intraluminal transformation of the secretory products discharged by the gland cells lining the lumen, are illustrated by a series of photographs.6. The glands have a poor blood supply and appear to be apocrine. It is unlikely, therefore, that the sweat glands of Ayrshire cows function as effectively in heat regulation as human sweat glands.7. The number of sweat glands per sq.cm. of skin was measured in all the regions. The average number was 1871 per sq.cm., ranging from about 1000 in the lower limbs to about 2500 in the axilla and neck regions.8. The length and circumference of the gland were measured, hence its secretory surface was calculated. The average area of secretory surface of a single sweat gland was 0·22 sq.mm., while the average area of secretory surface of the sweat glands per sq.cm. of skin was 3·94 sq.cm. There was a significant negative correlation between the number of glands per sq.cm. and the area of secretory surface of a single sweat gland.9. The ventral region of the neck, the axilla and upper hindleg had the largest area of secretory surface per sq.cm. of skin, while the forehead, back (sacral), gluteus, lower foreleg and hindleg had the smallest.10. The only region which had a significantly smaller area of secreting surface than the front flank region was the sacral region of the back.

Description: 1. Since the pigmentation of the skin cannot be assessed by visual examination of the hair or hide, a simple and convenient method of grading the cutaneous pigmentation of cattle based on the microscopic examination of skin sections has been described.2. The degree of cutaneous pigmentation of the skin of twenty body regions of three Ayrshire cows, two Ayrshire bull calves, two Sudanese Zebu bulls, one Sudanese Zebu cow and one Jamaican Zebu cow have been assessed by this method.3. The skin of the Zebu cattle was found to be much more heavily pigmented than that of the Ayrshire cattle.4. The dorsal and lateral regions of both the Zebu and the Ayrshire cattle were more pigmented than the ventral and leg regions.