A review implicating a two compartment model for the processes
of cell division and differentiation in the Wool Follicle
D.R. Scobie, J.L. Woods
Wool Research Organisation of New Zealand (Inc.), Private Bag,
Christchurch
Proceedings of the New Zealand Society of Animal Production.
1992, 52: 265-272
The determinants of wool production per unit area of skin are
reviewed, and found to be dominated by follicle volume. Evidence is
presented to show that follicle cells destined to become fibre cells
differentiate into a continuum of cell types rather than discrete
populations of medullary, ortho- and paracortical cells as the
literature suggests. Fibres of the same dimensions grown by a sheep at
one point in time contain differing proportions of these cell types. It
is hypothesised that there is a degree of independence between fibre
volume and cell differentiation. Medulla formation is explained in
terms of competition between follicles for keratin precursors, so that
fibre volume exceeds the available volume of keratin. A similar
mechanism is proposed for the cortex, where paracortex and mesocortex
become less prevalent as total fibre volume increases. It is concluded
that a model for fibre formation can be considered in two parts: one
which generates fibre volume and another which determines cell type
within that volume.
Keywords: NZSAPAB;
Wool production; wool follicles; follicle competition; fibre
volume; orthocortex; paracortex; medulla; model.
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Last Updated 25-01-1997
