The Spatial Relationships Between Central Primary Skin Follicles During their Development in Sheep

Abstract

SwmmaryThe spatial patterns of central primary follicles have been measured during development and compared on six body positions and hetween Romney X South. down cross and Merino shepp. The patterns are similar in both breeds on aU the body positions investigated and appear to be constant between 70 and 140 days of foetal age.The actual measurement of spatial relationships shows that the distribution of central primary follicles is highly uniform, and gives support to the idea that these follicles 'may compete for space during their initiation.The marked directional.trend of the trio groups does not appear to be associ· ated with a directional component in t,he spatial arrangement of central primary follicles.

The Spatial Relationships Between Skin Follicles During Their Development in Sheep

“…The spatial relationships between central primary follicles during their initiation and development ,vere reported in an earlier paper (Claxton 1962). The results shO\ved that the pattern of central primaries was similar in six body regions of both Romney X Southdown cross and Merino sheep, and that it was invariant during initiation and subsequent foetal development.…”

“…Schinckel (1955), Stephenson (1959), and Schinckel and Short (19GI) have concluded that heavier foetuses have a greater total number of primary follicles. The distribution of central primary follicles is highly uniform yet there is no evidence that the pattern has a directional component (Claxton 1962). These considerations suggest that the mechanism controlling the distribution of central primary follicles may be a competitive one whereby new follicles appear at sites most distant from existing follicles.…”

“…The high variation of density and of mean distance to nearest neighbour among primary fol1icles at 90 days has resulted mainly from marked differences in two pairs of duplicate recordings-the same pairs ,vhich were responsible for high error estimates in the measurements among central primary follicles (Claxton 1962).…”

“…The foHicle counts on which density estimates were based were adjusted for these changes with methods described by Carter and Dowling (1954). Claxton (1962) compared two methods of adjusting interfollicle measurements for the effects of shrinkage and distortion, and found both gave similar results with equal accuracy. The more simple method of correction using a ratio of the original skin sample diameter to a mean of four equally spaced section diameters has been adopted here.…”

“…A mean distance to nearest neighbour for the primary follicles in each section was calculated from 10 distances using central primaries as centres and 16 distances using latera1s as centres. These numbers are in proportion to the ratio PL : PC, which was founei to be about 1·6 (Claxton 1962). The R values derived for the total follicle population are based on a mean distance to nearest neighbour using 40 individual distances, the follicle centres from which they were made being chosen from a random number series in a field containing about 100-]40 follicles.…”