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Biomedical subjects

D M Jenkinson

Publications and source records attributed to D M Jenkinson.

At least 55 records · Page 3Linked to original sources
PubMed1979

Structure of the epidermis in Ayrshire bullocks.

The living epidermis and stratum corneum of cattle, when measured on cryostat sections, were both found to be approximately 30 micrometer thick. However, the corneum contained about 30 cell layers, whereas the living epidermis was composed of only four. Histological processing involving fixation, dehydration and paraffin embedding, resulted in the loss of half of the stratum corneum and proved to be unsuitable for study of this layer. Lipid derived mainly from the sebaceous gland was present between the squames in the outer two thirds of the corneum probably in the form of an emulsion with sweat.

Animals↗
PubMed1979

Structure of the sheep epidermis.

The stratum corneum measured on fresh frozen sections was found to be considerably thicker than previously reported. It was uniformly permeated with sebum, which also formed an intact film over the skin surface and it could readily be divided into two zones. The living epidermis was approximately half as thick as the stratum corneum.

Animals↗
PubMed1979

The effects of some surface sampling procedures on the stratum corneum of bovine skin.

Clipping and shaving remove cell and lipid layers from the stratum corneum and also modify the effects of subsequent lipid collection and microbiological sampling techniques. The damage to the epidermis caused by solvents indicates that further evaluation of some sebum collection procedures and of the effects of dips and dressings applied to the skin is required.

Animals↗
PubMed1979

Location of immunoglobulins in the skin of cattle and sheep.

The pattern of distribution of immunoglobulins (Ig) found within the skin of cattle and sheep was the same in both species. IgA was detected mainly in the sweat gland duct and in the intercellular spaces of the living epidermis. IgG was also located at the latter site but was found in greater amounts throughout the dermis and in the endothelium of the blood vessels. IgM was primarily located at the basement membrane of the epithelial structures, in the hair papilla and in the walls of the blood vessels. Lower concentrations of IgM were also detected in the upper dermis.

Animals↗
PubMed1979

The ultrastructure of the sweat glands of the ox, sheep and goat during sweating and recovery.

The ultrastructure of the sweat glands of cattle, sheep and goats was studied before, during, and after, exposure of the animals to controlled warm environments. In cattle, sweating induced little ultrastructural change in the gland, although fluid-filled spaces appeared between the myo- and secretory epithelial layers. The mechanism appears to be one of fluid transport and exocytosis of secretory vesicles, which in this species seem to be derived from the Golgi apparatus and/or mitochondria. The glands of the sheep and goat also displayed signs of vesicle exocytosis and of fluid transport during sweating. The sweating 'fatigue' in these species was apparently due to failure of the secretory cells, some of which ruptured and were extruded into the lumen. The evidence during subsequent recovery indicates that neighbouring cells spread to make contact, encase remnants of atretic cells between them and the underlying myoepithelium, and engulf them. Sweat in these species appears to be formed (a) by secretion and (b) from cells which can no longer meet the demands of stimulation. The role in sweating of cell replacement, and of undifferentiated cells found between the myo- and secretory epithelia, is discussed.

Animals↗
PubMed1978

The effect of aluminium chlorhydrate on sweat gland activity in cattle.

Topical application of aluminium chlorhydrate had no appreciable antiperspirant action on the epitrichial glands of cattle. There was no evidence of penetration of the salt into the dermis or of any change in the morphology of the glands. It is probable that the antiperspirant activity of aluminium chlorhydrate in the human axilla, is only on the atrichial glands.

Aluminum↗
PubMed1978

Studies on the nature of the peripheral sudomotor control mechanism.

Electron microscopical studies of the sweat glands of the body surface of the cow, sheep, goat and cat demonstrated that there were few nerves or blood vessels near the glands. No varicosities were found within 10 micron of the glands, and the small number of unmyelinated nerve bundles traced were over 1.5 micron from the glandular myoepithelium, and situated outside a fibrocyte sheath surrounding the glands. It was concluded that the sweat glands of these species are not innervated. Unmyelinated nerve fibres were more abundant around, and were closer to, the sweat glands of man, the horse and cat footpads, and varicosities were observed within the fibrocyte sheath close enough to have a direct influence on the glands. It is postulated from the comparative evidence that the basic sudomotor mechanism is the same in all species, involving the action of adrenergic and cholinergic nerves on the cutaneous blood vessels and local catecholamine transfer to the gland; and that in species such as man where the blood supply and sympathetic nerves are in close proximity to the glands, transmitters released at the sympathetic nerve endings, in particular acetylcholine, will, in addition, have a direct action on the glands.

Adult↗
PubMed1978

In vivo changes in the composition of cattle skin surface lipid with time.

The skin surface lipid composition was examined in cattle over a period of 13 days after cleaning the skin at 15 degrees C and 35 degrees C. Little change was observed in the concentrations and fatty acid compositions of all the major sebum fractions other than the unesterified fatty acids. Changes which occurred in the proportions of fatty acids present in the unesterified fatty acid fraction were similar at both environments. At 15 degrees C the total amounts per unit area of unesterified fatty acids on the skin did not alter significantly with time. However, at 35 degrees C there was a significant increase in the total amounts of unesterified fatty acids per unit area and concomitant increases in the amounts of individual fatty acids, in particular linoleic acid.

Animals↗
PubMed1976

The effects of exposure to warm environments on bovine plasma lipid composition.

The concentrations of total fatty acids and free cholesterol in the plasma of Ayrshire calves decreased following, but not during, short-term exposure to heat. Lower concentrations of total fatty acids and free cholesterol were maintained on prolonged heat exposure. Blood and plasma volumes were little affected by either short-term or prolonged heat exposure. Haematocrit rose during short-term heat stress and on prolonged heat exposure there was a decrease in erythrocyte fragility.

Animals↗
PubMed1975

Relationship between lipids in plasma and skin secretions of neonatal calf with particular reference to linoleic acid.

A study has been made on the lipid composition of the skin secretions and plasma of the neonatal calf. A significant proportion of the skin surface lipids was comprised of triglycerides. Saturated fatty acids comprised the major proportion of the fatty acids of the skin surface triglycerides at birth. Immediately after birth, the proportion of the saturated fatty acids decreased, and there was a concomittant increase in the proportion of 18:1. Some 3-4 weeks after birth, the proportion of 18:2 delta cis-9, cis-12 in the skin surface triglycerides increased to ca. 14 percent, and there was a decrease in the proportion of 18:1. The 18:2 was shown to be confined almost entirely to the 2 position of the triglycerides. During the first 5 weeks after birth, the concentrations of the cholesteryl esters and phospholipids in the plasma increased markedly and were accompanied by a rapid increase in the proportion of 18:2 within these 2 fractions. The results are discussed in relation to the known role of 18:2 in the metabolism of biological systems.

Animals↗
PubMed1975

Inheritance of some sweat gland and hair follicle characteristics in cattle.

Using measurements made in cows in the herds of the Hannah Research Institute (Ayrshire), the West of Scotland Agricultural College (Ayrshire and Friesian) and in the twin herd of the Animal Breeding Research Organisation (Ayrshire), repeatability and heritability estimates were obtained for three hair follicle and four sweat gland traits. Average repeatability was high (50-70%) for all characters except angle of slope of the hair (18%). Heritability estimates were extremely variable among the different herds and methods of measurement but there was evidence of considerable genetic variation, particularly for sweat gland traits. The most consistent heritability estimate (30-45%) was given by the ratio of sweat gland length to diameter. The potential of skin types for the selection of cattle for tropical regions is discussed.

Age Factors↗
PubMed1975

The corticosteroid content of cattle skin washings.

In vitro techniques have been developed to study the invasive processes of Fasciola gigantica. The conditions necessary for excystment were identical with those required by F hepatica. The ability of larvae to penetrate mouse gut in vitro was influenced by the composition of the fluid within the gut, and by the region of gut wall to which the larvae were exposed. Larvae remained viable on spleen cell monolayers for at least 60 days.

Adrenal Cortex Hormones↗
PubMed1975

The sweat glands and hair follicles of different species of bovidae.

Measurements were made of hairs and sweat glands in the skins of a number of different Bovidae. The principal differences between the Bovinae and the one member of the Cephalophinae (the duiker) studied were in the dimensions of the skin and its component organs and in hair density; secondary hairs were not present, although in the American bison small primary follicles which appeared to provide a woolly undercoat were seen. In contrast, secondary hair follicles were found in the skins of all the Caprinae, Antilopinae and most of the Hippotraginae studied. The sweat glands of the Bovidae varied in shape from simple sacs as seen in the oryx to the coiled tubes of the wildebeest, and different markedly in size, the largest being found in the wisent.

Animals↗
PubMed1975

The effect of environment on sebum output and composition in cattle.

In an investigation into the effect of short-term exposure to different temperatures and humidities on the sebaceous glands of Ayrshire calves it was concluded that temperature had no appreciable effect on sebum output or its fatty acid composition. At a low humidity, however, the cutaneous outputs of palmitic and myristic acids were higher. On prolonged exposure to a warm environment, a higher output of sebum occurred together with an increase in the percentage of linoleic acid in the sebum.

Animals↗
PubMed1974

Sweat proteins.

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Animals↗