Five adult Barki ewes of each of the four cotting levels: high, medium, low and
zero were used. All the experimental animals grazed at Maryout Research Station (35
kilometers south west of Alexandria). Observations on cortical segmentation of fibres
in the follicles were conducted . The nature and presence of bilateral and radial cortical patterns of coarse
Barki wool sheep is observed and discussed in relation to some physical properties of
cotted fibres. The asymmetry in the cortex was studied using skin sections. The
bilateral structure was present in both primary lateral and secondary fibres.
Differences (p < O.05) occurred in mean area of par- cortical segment and mean ortho-
to para- ratio between different cotting levels. The coarse wool fibres which were
associated with low cotting levels were found to have the radial asymmetry which
originated from the primary central follicles. Regardless of follicular origin, there was a significant increase in the
percentage of radial cortical type and a decrease in bilateral cortical type percentages
with increasing cotting level, therefore selection for increasing bilateral pattern in
fibres, through increasing SIP ratio, might contribute to a reduced ability towards
cotting.