Variations in Wool Follicle Morphology

Orwin, D.F.G.

doi:10.1007/978-94-011-9702-1_16

Cited by 9 publications

(5 citation statements)

References 56 publications

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“…III. Hair germ cells and cells of the bulge region contribute to di¡erent layers of the anagen HF Despite a belief that all layers of the HF are products of the hair matrix germinative cells (e.g., Orwin, 1989), recent studies using a hair reconstitution assay demonstrated that regeneration of IRS/hair shaft and ORS involves di¡erent progenitor cells (Kamimura et al, 1997). The same results were obtained using in vivo transduction of mouse skin with b-gal-encoding retroviral vectors (Ghazizadeh and Taichman, 2001).…”

Section: The Hypothesis Of Hair Follicle Predeterminationmentioning

confidence: 85%

Hair Follicle Stem Cells

Lavker

Sun

Oshima

et al. 2003

Journal of Investigative Dermatology Symposium Proceedings

141

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The workshop on Hair Follicle Stem Cells brought together investigators who have used a variety of approaches to try to understand the biology of follicular epithelial stem cells, and the role that these cells play in regulating the hair cycle. One of the main concepts to emerge from this workshop is that follicular epithelial stem cells are multipotent, capable of giving rise not only to all the cell types of the hair, but also to the epidermis and the sebaceous gland. Furthermore, such multipotent stem cells may represent the ultimate epidermal stem cell. Another example of epithelial stem cell and transit amplifying cell plasticity, was the demonstration that adult corneal epithelium, under the influence of embryonic skin dermis could form an epidermis as well as hair follicles. With regards to the location of follicular epithelial stem cells, immunohistochemical and ultrastructural data was presented, indicating that cells with stem cell attributes were localized to the prominent bulge region of developing human fetal hair follicles. Finally, a new notion was put forth concerning the roles that the bulge-located stem cells and the hair germ cells played with respect to the hair cycle.

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Section: The Hypothesis Of Hair Follicle Predeterminationmentioning

confidence: 85%

Hair Follicle Stem Cells

Lavker

Sun

Oshima

et al. 2003

Journal of Investigative Dermatology Symposium Proceedings

141

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“…However, the poor monthly correlations between these parameters, and the lack of precise correspondence between fibre diameter and length-growth cycles for individual sheep and individual fibres in our study suggest that photoperiod control of these parameters must be very complex. In cellular terms, fibre diameter and length-growth are determined by the rate of supply of cells from the follicle bulb, the size to which cells grow, and the way in which they stack during fibre formation -diameter growth requiring cells to stack preferentially side-by-side and length-growth, end-to-end (Orwin 1987). However, the cellular mechanisms involved in these processes, and the way in which photoperiod may modify them are poorly understood.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations in the dimensions of individual Romney wool fibres determined by a rapid autoradiographic technique

Woods¹,

Orwin²

1988

New Zealand Journal of Agricultural Research

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A technique for radio-labelling short regions of growing wool fibres was modified by using intradermal injections of 3H-cystine and a rapid detection method. This technique allowed emergence times and dimensional changes of individual wool fibres to be rapidly and precisely monitored. Seasonal changes in fibre dimensions were determined for five sheep on maintenance nutritional levels following monthly injections over 12 months. Fibre diameter and length-growth varied seasonally, maximum and mimimum values occurring in summer and winter respectively. However, the amplitude and timing of each of these cycles differed between sheep and between fibres from individual sheep. As a consequence, the seasonal cycle in wool production (i.e., fibre volume) may be brought about by different combinations of fibre diameter and length-growth changes. Monthly diameter and length-growth measurements were often poorly correlated, suggesting that the cellular/physiological mechanisms determining these parameters in the follicle are complex.

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“…Cortical cell volume was correlated with fibre production per follicle, as was the case when fibre production was altered by nutrition (Wilson and Short 1979). This correlation may be due to a relationship between cortical cell type and fibre size, since it is known that fibres with large diameters tend to have a high proportion of the large orthocortical cells (Orwin 1988). …”

Section: Determinants Of Fibre Productionmentioning

confidence: 84%

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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Variations in Wool Follicle Morphology

Cited by 9 publications

References 56 publications

Hair Follicle Stem Cells

Hair Follicle Stem Cells

Seasonal variations in the dimensions of individual Romney wool fibres determined by a rapid autoradiographic technique

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

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