Glands| | | | | | Presence of eosinophilic cuticle helps distinguish eccrine duct from coil histologically | | | | | |
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- Most important function is to regulate body temperature through evaporative heat loss
- Composed of three sections:
- Acrosyringium: intraepidermal spiral duct opening to surface of skin
- Straight duct: within dermis and consisting of double layer cuboidal epithelium lined by eosinophilic cuticle on luminal side
- Secretory eccrine coil: within deep dermis/subcutaneous fat and consists of two different cells (glycogen-rich, pale cells, and smaller darker cells) which appear to fit together in one layer, outer portion contains myoepithelial cells
- Positive for S100, keratin, and carcinoembryonic antigen (CEA)
- Found everywhere except: clitoris, glans penis, labia minora, external auditory canal, and lips
- Eccrine glands possess cholinergic innervation (acetylcholine) but paradoxically derived from sympathetic outflow (which typically uses norepinephrine, not acetylcholine), thus functionally cholinergic but anatomically sympathetic; merocrine secretion
Apocrine Glands- Generally confined to axillae, breast (mammary gland), anogenital region, external auditory canal (ceruminous gland), and eyelids (Moll’s gland)
- Secretion via decapitation (portion of cell pinched off and enters lumen)
- Responds mainly to sympathetic adrenergic stimuli
Sebaceous Glands- Formed initially as outgrowth from upper portion of hair follicle; contains lobules of pale-staining cells characterized by lipid vacuoles; holocrine secretion with distention of sebocytes (filled with lipid vacuoles) until shed into lumen
- Found throughout skin except palms and soles
- Always associated with follicles except following locations (‘free’ sebaeceous glands):
- Gland of Zeis → found on superficial eyelid margin (near Moll’s gland)
- Meibomian gland → tarsal plate of eyelids (behind Moll’s gland)
- Montogomery tubercle → nipple and areola
- Tyson’s gland → external fold of prepuce (genitalia)
- Fordyce spot → vermilion border of the lips and buccal mucosa
- Gland under adrenergic hormonal control; enlargement at puberty due to ↑ androgens
- Lipid composition of sebum: 57% triglycerides, 25% wax esters, 15% squalene, <3% cholesterol and cholesterol esters
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