author(s)
Sukanta Das, Sarma Kabita and Talukdar Manmath

abstract
The present investigation was conducted in 18 numbers of Assam Hill Goat divided into three groups (preruminant (0-3 weeks), Transitional (3-8 weeks) and ruminant age groups (above 8 weeks) with six numbers of animals in each group to investigate the Histomorphometric feature of hair follicular feature of Assam Hill Goat. Study revealed two types of hair follicle viz. primary and secondary. Primary being associated with the muscle arrector pilli, sweat gland, sebaceous gland (Mono and bi lobbed) with larger diameter than secondary follicle. Secondary follicles were occasionally associated with sebaceous gland (Mostly monolobbed). Primary follicles were arranged in single, trio, or in group. Follicular groups were well defined in ruminant age groups. The longitudinal section of hair follicle showed infundibulum, isthmus, supra bulbar and bulbar region. Isthmus was the thickened outer root sheath with distinct darkly stained nucleated cell. Dermal papilla was well defined cone shaped with dark stained connective tissue cells. Matrix region of the hair follicle showed differentiated and non differentiating zone with cell dividing figure. Melanocytes were found on the basement of dermal papillae. In cross section hair follicle was round in profile with medulla, cortex, cuticle, inner root sheath, outer root sheath and connective tissue sheath. The inner root sheath was keratinized with 2-3 layered flat nucleuses. Outer root sheath was consisted of 3-4 layers of large cell with thin cytoplasm and the outer layer with obliquely directed nucleus. The hair follicle, sweat and sebaceous gland was covered by abundant on collagen, reticular and elastic fiber. Abundance of elastic fibers was found at the insertion site of arractor pilli muscle. Network of connective tissue in form network at the base of hair follicle was observed in cross section. Various micrometrical parameters like length of hair follicle, breadth and length of hair bulb, dermal papilla, diameter of primary follicle was found to be significantly higher during ruminant age groups than preruminant and transitional age groups.