The Effect of Sympathectomy on Wool Growth

Ferguson, KA

doi:10.1071/bi9490438

Cited by 12 publications

(13 citation statements)

References 4 publications

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“…The differences in the weight of the haircoat are less easily explained on the basis of the above hypothesis. In sheep, Ferguson (1949) has shown that if the animal is unilaterally sympathectomized, wool growth is enhanced on the side where the nerves have been cut. From this fact it might be expected that the pigs in the warm climate with the better blood supply would have the greater quantity of hair.…”

Section: Discussionmentioning

confidence: 99%

Morphological Changes in Swine Associated with Environmental Temperature

Weaver¹,

Ingram²

1969

Ecology

101

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Ten animals from two litters of English large white pigs were weaned at 12—15 days of age and placed one per cage within constant—temperature rooms. In the first group, a comparison was made between three animals raised at 5°C and their littermates raised at 35°C. There were marked differences in appearance and in gross morphology. Those from the cold environment had more hair, were shorter and more stocky, and had a shorter tail and smaller ears than their littermates. A second group of animals were raised at 20°C and 35°C; it was found that with respect to all measurements the 20°C pigs were intermediate between the 5° and 35°C animals. These observations accord with Bergmann's Rule that animals raised in colder environments are characterized by a reduced surface area/body weight ratio. The results likewise substantiate Allen's Rule that in colder climates the length of appendages and of extremities is reduced.

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Section: Discussionmentioning

confidence: 99%

Morphological Changes in Swine Associated with Environmental Temperature

Weaver¹,

Ingram²

1969

Ecology

101

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“…Perhaps the increased wool production per follicle was partly due to the greater availability of nutrients following the destruction of many of the cutaneous nerves. Ferguson (1949) obtained a mean increase of 36 % in wool growth rate for 10 weeks following unilateral sympathectomy and suggested that it was due to vasodilation of the denervated vessels. Slen (1958) suggested that mechanical trauma (such as that caused when a sheep is bumped), with its concomitant increase in blood supply to the site of injury, stimulated the growth of wool.…”

Section: Discussionmentioning

confidence: 99%

Effects of Grafting the Skin in Merino Sheep, With Special Reference to the Growth of Wool and Hair

Lyne¹,

Hollis²

1980

Aust. Jnl. Of Bio. Sci.

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Grafts of wool-growing trunk skin (wool grafts) and hair-growing inguinal skin (hair grafts) were studied in two black and two black and white adult Merino sheep. Skin growing black wool was transplanted to skin growing white wool and vice versa. Also, skin in both black and white regions was excised and returned to the same site. Inguinal skin was transplanted to black wool-growing skin.The areas of the grafts, which initially ranged from about 1 to 25 cm 2 , decreased to a minimum by 28 days after grafting. Most grafts then expanded slowly and returned to approximately their original size by the end of the experiment (118-194 days after grafting).Grafting caused the temporary cessation of wool and hair growth. Old fibres were shed and new fibres, usually similar in colour, appeared above the skin surface about 28 days after grafting. Each animal was given a series of injections of L-[35Sjcystine and fibres were sampled from the grafts and control regions for length and diameter measurements. The fibres on most of the grafts showed marked increases in length growth rate and diameter, resulting in large increases in volume growth rates. However, the total amount of wool produced by the grafts was usually reduced because grafting caused a loss of follicles.At the end of the experiment, skin samples were taken from the grafts and control regions for microscopic examination. The sebaceous glands were retained in the grafts except those associated with follicles that did not regenerate. The sweat glands and erector muscles were often destroyed by grafting, particularly in the wool grafts. Innervation was greatly reduced. Langerhans cells appeared to be as numerous in the grafts as in control samples. Melanocytes spread from black skin into wool and hair grafts of white skin and were most commonly seen in the epidermis, which increased in thickness. Clumps of pigment in the dermis appeared at the periphery of many of the grafts.

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“…Perhaps the faster length growth rate, or increased length of the hair growth cycle, was partly due to the availability of more nutrients following the destruction of the sweat glands and many of the cutaneous nerves. Ferguson (1949) reported an increase of 36% in wool growth rate following sympathectomy and suggested that it was brought about by vasodilation of the denervated blood vessels. Further studies are needed in order to determine the influence of the various skin structures on the growth of hair or wool.…”

Section: Discussionmentioning

confidence: 99%

Effects of Freezing the Skin and Plucking the Fibres in Sheep, With Special Reference to Pigmentation

Lyne¹,

Hollis²

1968

Aust. Jnl. Of Bio. Sci.

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SummaryMacroscopic and microscopic changes in the skin of seven adult Suffolk and Merino sheep were studied for periods of up to 513 days following the application of solid carbon dioxide to hair-and wool-growing areas after clipping or plucking of the fibres. Observations were also made on the effect of plucking alone.A colour change from black to whit,e occurred in the coat subsequent to freezing skin which previously grew black hair in Suffolks and black hair or black wool in Merinos. In contrast, follicles which grew white wool in Suffolks and in an isolated white area on an otherwise "black" Merino sheep were induced to grow black or partially coloured fibres for periods ranging from a few days to several months when damaged by freezing the skin or plucking the fibres. The outer root sheaths of the follicles in the regions which normally grew white wool in these animals were the only source of the melanocytes which appeared near the dermal papillae of regenerating follicles and passed pigment into the new fibres. When the skin was frozen after the fibres had been plucked, the melanocytes in the follicle outer root sheaths were usually destroyed and the new fibres were non-pigmented.Other changes which frequently resulted from freezing the skin were an increase in the thickness of the epidermis, destruction of the sweat glands, a reduction in the number of follicles per unit area of skin, and a reduction in the innervation of the skin. No follicle neogenesis was seen. An increase in the length of the fibres, due either to an increased growth rate or to an increase in the duration of the growth cycle, sometimes occurred.

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The Effect of Sympathectomy on Wool Growth

Cited by 12 publications

References 4 publications

Morphological Changes in Swine Associated with Environmental Temperature

Morphological Changes in Swine Associated with Environmental Temperature

Effects of Grafting the Skin in Merino Sheep, With Special Reference to the Growth of Wool and Hair

Effects of Freezing the Skin and Plucking the Fibres in Sheep, With Special Reference to Pigmentation

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