Eylem Seç
Studies in the physiology of temperature regulation in cattle.with special reference to the mode of action of the sweat glands in Bos taurus
Başlık:
Studies in the physiology of temperature regulation in cattle.with special reference to the mode of action of the sweat glands in Bos taurus
Yazar:
Jenkinson, David McEwan, author.
ISBN:
9780438057432
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (137 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: R. C. Garry.
Özet:
1) The effect of fixation on the histological appearance of bovine sweat glands and of their contained secretion was studied. Six fixatives were used, each followed by the same method of processing. This method had a short dehydration time and employed carbol-xylol as clearing agent. The sweat glands with all six fixatives had a flat secretory epithelium and contained a secretory product. The appearance of this product varied with the fixative used, some failing to fix it adequately, but the secretion consistently appeared colloid-like after fixation with Susa and this was found to be the most suitable fixative for study of the contents of bovine sweat glands. 2) Tissues processed by another method involving a longer period of dehydration and using chloroform instead of carbol-xylol as principal clearing agent after fixation with Susa confirmed the colloid-like appearance of the products in the glands and the suitability of the technique used. Examination of histological specimens from cattle of different breeds, ages and sex showed the sweat glands in temperate breeds (Bos taurus) in Scotland to be always full of a colloid-like secretion and to have a flat epithelium. Apocrine secretory stages were not detected. 4) Failure to detect apocrine stages in the sweat glands conflicts with the findings of Findlay & Yang (1950). The possibility that the method of Findlay and Yang was more suitable for detecting such stages and the conflicting results recorded after the use of this technique led to a re-examination of their method. The glands, in the histological sections obtained by the method of Findlay & Yang, exhibited configurations which could be interpreted as stages of secretion, but close examination of the sections led to the conclusion that these were not stages of true apocrine secretion. 5) To substantiate this conclusion the method of Findlay and Yang involving the use of Bouin as fixative was repeated after the tissues had been fixed instead in Susa which was previously shown to be the best fixative for the sweat gland contents. When this was done most of the glands were found to be devoid of secretion although a few contained tissue fragments and some a colloid-like material. 6) Part of the method of Findlay and Yang but using Susa fixation was next tested to determine the effect of processing. After this processing most of the glands were found to be full of a colloid-like material, and, as far as could be determined from the thick sections obtained, they had a flat secretory epithelium. It was therefore concluded that the method of Findlay and Yang was unsuitable for processing the sweat glands for study of their products and that it presents no evidence for true apocrine secretion. The conclusion was therefore reached that the sweat glands in Bos taurus under normal conditions in Scotland have a flat epithelium and are always full of a colloid-like secretory product. 7) An attempt was made to empty the sweat glands in the Ayrshire calf by means of suitable stimuli and to measure any subsequent apocrine cycle by taking biopsy skin specimens before and at intervals after stimulation. Two stimuli were used for this purpose (1) heat and (2) adrenaline which had been shown by previous workers to be an activator of cattle sweat glands. These stimuli, although applied in extreme as well as in physiological doses, failed to empty the glands, which, in the large number of sections taken before and after treatment, were always found to be full of a colloid-like material and, except after extreme doses of adrenaline, to have a flat epithelium. Extreme doses of adrenaline (0.2 ml and 1.0 ml, 10-3 g/ml) administered intradermally caused an increase in the height of the glandular epithelium and subsequent degeneration of the cells. The excessiveness of these doses was clearly seen also on brown areas of skin where the intense vasoconstriction caused by the drug resulted in the hair growing in white instead of brown. Evidence for the functional activity of these glands was obtained after exposure of the cattle to heat where measurements of the volume of sweat glands per sq cm of skin indicated that this volume decreased after subjection to warm environments. After intravenous injection of adrenaline (2.0 ml, 10-3 g/ml) visible evidence of sweating activity was obtained. The sweat glands in the calf therefore are functional and act in a manner which does not involve degeneration of the glandular epithelium.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684602.1) | 684602-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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