Factors Influencing Cellular Events in the Wool Follicle

Pi, Huifeng

doi:10.1007/978-94-011-9702-1_12

Cited by 13 publications

(9 citation statements)

References 32 publications

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“…The activity in the germinative region of the Merino sheep exemplifies well this particular point. In the germinative region of the average wool follicle bulb there are about 800 cells and between 20 and 40 of these complete mitosis every hour, giving a population turnover time of between 20 and 40 hours (Hynd, 1989). The fuel to drive such an amazing turnover rate must be both rich and constantly and readily available and Hynd (2000) has identified the sources that could be involved.…”

Section: Hair Folliclesmentioning

confidence: 99%

Growth of farm animals

2012

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Index x Contents Preface to First EditionAn understanding of the processes which change the size, shape and composition of farm animals is fundamental to all aspects of production which seeks to meet the dietary and other needs of human populations. This book attempts, within the limits of a basic undergraduate text, to give a comprehensive picture of how animals grow, change in shape and in composition, and to describe those factors which affect growth processes and which dictate the extent and direction of changes within the animal.The overall scene we have attempted to present is a progression from cell to tissue to entire animal, as well as a description of those factors within the animal, particularly hormones, genes and gender, which fashion this progression. In addition, an attempt has been made to give perspective to the manner in which such a complexity of changes affects the approach to, and understanding of, concepts of efficiency. However, it was felt that the framework would not be complete without first setting the scene in the context of some of the principles which govern size and shape in all animals and, second, describing the methods which may be used to measure the overall results of the processes which have been described. Deliberately, the effect on growth which exogenous factors such as hormonal implants, antibiotics and other intestinal tract manipulators may have has not been considered. Although the use of such manipulators may be transitory and dependent on political and other pressures, basically they were not considered to be appropriate to the general thesis. Whilst it is acknowledged that poultry are farm animals of great importance in producing food for the human, largely through a dearth of appropriate detailed information and because of the approaches to production which are used in practice, this book concentrates on cattle, sheep and pigs.In our student days we were endlessly fascinated by the seminal studies of D'Arcy Thompson, by the profound work of Brody at Missouri and by the inspired and inspiring work and writing of Hammond and his associates at Cambridge. To no less an extent we found the sheer variety of animal cells and the immensely complex tissues that they form, and which give ultimately the overall growth responses, both amazing and mind gripping. These fascinations have remained with us ever since and in our working lives we have been fortunate to have had the chance to make some contributions to some of those areas which have so consistently intrigued us and occupied our thoughts. As students the writings of those great men above were those to which we turned. Today much of their basic thinking still holds good and leads the enquiring mind in the right direction when considering the problems of how best farm animals may be grown to yield products for the human. However, there is no book which as a complete entity has updated their basic thinking and which takes the reader from cell to complete animal based on original classical anatomical studies and the quantit...

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Section: Hair Folliclesmentioning

confidence: 99%

Growth of farm animals

2012

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“…Although thyroxine may have a direct effect on the regulatory mecha nisms of follicle mitotic rate and cell commitment (Hynde 1989), it is not sufficiently specific in its action to be used as an exogenous stimulant. Tissue specificity may be achieved through transgenic techniques, al though this would involve use of a more specific promoter than the untargeted metallothionein or PEP carboxykinase systems.…”

Section: Regulation Of the Partition Of Nutrient Supply Between Tmentioning

confidence: 99%

Amino Acid and Energy Metabolism in the Peripheral Tissues of Ruminants

Harris¹,

Lobley²

1991

Physiological Aspects of Digestion and Metabolism in Ruminants

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“…Similarly, systemic hormonal differences between genetically-different sheep are small and inconsistent (Williams et al 1986;Hynd 1988;Williams et al 1990), as are differences in the level of various metabolites, with the exception of cysteine (Williams et al 1972;Williams 1976). Difference in plasma cysteine levels between genotypes are probably a reflection of a differential ability of the follicles to extract and utilise the amino acid.…”

Section: Discussionmentioning

confidence: 99%

Cellular characteristics of wool follicles and fibres in finewool and strongwool Merinos

Edwards¹,

Pi²

1992

Aust. J. Agric. Res.

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The genetic differences in the structure and function of wool follicles and their association with wool and fibre production were examined in 6 finewool Merinos (Camden Park) and 6 strongwool Merinos (East Bungaree). The strongwool Merinos produced 2.4 times more wool per unit area of skin and 3.5 times the volume of fibre per follicle than the finewool Merinos, when both groups were maintained under similar environmental conditions. The finewool Merinos had a higher follicle density, but a lower average volume of germinative tissue in the follicle bulb and the skin, than the strongwool Merinos. The number and volume of cells in the bulb, bulb cell production rate, cortical cell size and the proportion of bulb cells entering the fibre tended to be greater in the strongwool Merinos than the finewool Merinos, but were not statistically different between strains due to a high between-sheep, within-strain variation. In a stepwise linear regression, wool production per unit area was best predicted by the volume of germinative tissue in the bulb, together with follicle density. It is concluded that genotype determines the volume of potential mitotically-active tissue in the skin, however the dynamic mechanism of fibre production is not controlled by a single character, but rather a combination of a number of characteristics.

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Factors Influencing Cellular Events in the Wool Follicle

Cited by 13 publications

References 32 publications

Growth of farm animals

Growth of farm animals

Amino Acid and Energy Metabolism in the Peripheral Tissues of Ruminants

Cellular characteristics of wool follicles and fibres in finewool and strongwool Merinos

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