The outer surface of the palpebrae has an evenly distributed population of very small vellus hair follicles and eccrine sweat glands, more numerous on the temporal than on the nasal side. The undersurface of the thick epidermis of the palpebral shelves is deeply and intricately sculptured; nerves penetrate the epidermis. Cilia grow in imperfect rows of five to six in the upper and three to four in the lower lid. Ciliary follicles are free of arrector muscles and abound in pigment cells throughout their length, including the matrix. The follicles are surrounded by blood vessels and nerves, far in excess of those found in follicles elsewhere. Sebaceous glands (of Zeis) and glands of Moll, which open into the pilary canals of ciliary follicles, are supplied with many cholinesterase-reactive nerves. Meibomian (tarsal) glands have the most abundant supply of cholinesterase-reactive nerves we have found in any gland, cutaneous or otherwise.
Montagna W, Ford DM. Histology and Cytochemistry of Human SkinXXXIII. The Eyelid. Arch Dermatol. 1969;100(3):328-335. doi:10.1001/archderm.1969.01610270070017