The post-natal development of the skin follicle population of a strain of Merino sheep.

Abstract

Observations are reported on the development of the follicle population during post-natal life in three groups of sheep from a strain of Australian Merino. The primary follicle number is complete by birth, and changes in density thereafter merely reflect the normal skin expansion accompanying growth. This constancy with time of the primary follicle number validates the use of the ratio of secondary to primary follicles (S/P) as a measure of the development of the secondary follicles. The S/P ratio followed a sigmoid curve characterized by a small increase in the ratio during the first week, a large increase in the second, and a progressive decline in the rate of development of secondary follicles thereafter.