Histomorphogenesis of Arrector Pili Muscle in Prenatal Goat (Capra hircus)

Abstract

Study on the histogenesis of goat skin was conducted on the 36 goat embryo/foetuses of local non-descript breed.  The material was divided into three group’s viz. Group I (below 50 days of gestation), Group II (51-100 days of gestation) and Group III (101 days – 150 days of gestation) containing 12 foetuses each group. The skin samples were collected from eight different regions of body except in group I. The tissue samples were processed as per routine paraffin embedding technique.  5-6 µ thick sections were stained with hematoxylin and eosin method. The arrector pili muscle was observed first time in face region at 87 days gestation in the form of differentiating myocytes in dermis. At 94 days gestation the myocytes appeared in the dermis of neck, shoulder, back, abdomen, flank and thigh regions of goat foetus. From 99 days gestation the myocytes showed fiber like profile to form oblique rows of myocytes in the vicinity of hair follicles and in face regions these appeared as thin bundles of smooth muscles which were attached by their one end to the hair follicles and extended obliquely to the dermo-epidermal junction. From 118 days of gestation fully developed arrector pili muscles were observed on the obtuse angle side of hair follicles in all body regions except in chin region which were attached by their one end at hair follicle bulb and by the other end at dermo-epidermal junction.