Post-natal growth changes in the skin follicle population of the New Zealand Romney and N-type sheep

Abstract

Quantitative aspects of skin follicle population growth and maturation in post-natal life from birth to 16 months have been studied in four groups of N-type and non-N New Zealand Romneys. The following characters were observed on skin biopsy specimens from a standard position on the mid-side in all cases: total and primary follicle population density; ratio of secondary to primary follicles ; primary and secondary fibre diameter; primary/secondary fibre diameter ratio ; and the incidence and degree of primary and secondary fibre medullation.No important differences were found between the genotypes examined in any of these characters except primary fibre diameter , the primary/ secondary fibre diameter ratio ; and the incidence and degree of primary and secondary fibre medullation. These characters individually, but especially in combination, appear of great diagnostic value at all post-natal ages in discriminating N-type from non-N genotypes, in terms which reduce the number of assumptions necessary on the relations between the fibre types of the staple and the follicles of origin in the skin.