Pre- and post-natal development of skin characteristics in the one humped camel (Camelus dromedarius)

The skin of camel, as in other farm animals is formed of 2 main layers: the epidermis and the dermis. The hypodermis was clearly seen only in the mid-side position than in the other regions of the body. The epidermis began to appear as a single row of cells at 90 days, then both the epidermis and dermis were fully developed at 147 days of foetal life at which time the epidermis was differentiated into its 4 strata (corneum granulosum, spinosum and basale or germinativum). and the dermis was differentiated into papillary and reticular sub-layers. The plugs which Mould form the hail follicles began to appear at 147 days, while the hair fibres began to appear in its follicles at 268 days of foetal life. The follicles were clearly differentiated into primary and secondary follicles at 268 days of foetal life. The hair follicles were arranged in groups and were clearly seen at 375 days of foetal life. Each group consisted of 3 primary-follicles (1 central and 2 laterals) and several secondary follicles ton the ectal side of the primary follicles). The thickest secondary follicles (early secondary follicles) were situated near the primaries, while the more thin secondaries (late secondary follicles) were far from the primaries. The primary follicle was associated with a sebaceous gland, a sweat gland and an arrector pill muscle, while each secondary follicle was associated only with a sebaceous gland. The sebaceous glands that were attached to the primary follicles had large lobules, while those attached to the secondaries were small. The several lobules of the sebaceous glands open into a common short excretory duct. The sebaceous glands began to appear at 229 days of foetal life. The apocrine sweat gland was formed of a glandular tortuous part and its uppermost straight duct passed between ol beside the sebaceous glands lobules, then enlarged into a sac before it opened near the follicle opening at the skin surface. The glandular tortuous distal part was situated either at or lower than the level of the hair follicle bulb, and was formed of I layer of cuboidal epithelium. The sweat glands began to appear at 229 days of foetal life. The arrector pill muscle was formed of smooth muscle fibres. It ran fi om the lower part of the follicle to the area below the epidermis. The arrector pili muscles first appeared at 229 days of foetal life.