Embryology and Anatomy of the Integument

Anatomy of the integument is based on the major function of the organ, which is to serve as a boundary between environment and the remainder of the body. Additionally, the skin acts as a sensory organ, allows for movement, assists with thermoregulation, and aids immune function. Hair begins to form in developing fetus at approximately 9.5 months of gestation. In the full-term fetus, the normal hair coat density should be present. The integument system includes skin, hair, hooves, and skin glands. Embryologically, the integument is formed from the endoderm, ectoderm, and neural crest. Axons grow toward their target organs with variation in chemical difference between axons directing targeted growth. Horses only have primary hair follicles, distributed evenly in rows that are simple follicles. The axon is led on its route by a growth cone that depends on both attraction and repulsion through contact and chemical signals.