Histology of the Eyelid

> pars cutanea (covered by skin)> anterior palpebral surface

> derivatives of skin: hair follicles, sebaceous gll., eccrine sweat gll.> layers of striated muscles

> orbicularis oculi m. (& levator palpebrae superior m.)> tarsus / tarsal plate

> dense fibro-elastic plate> tarsales gll. / Meibomian gll.

> elongated holocrine gll. (modified sebaceous gll.)> compound gland, which opens freely (separate from hair follicles)

> tarsal muscles are anchored onto the plate> smooth muscle (!!!), innervated by sympathetic nerves

> pars conjunctivalis (covered by conjunctiva)> facies posterior palpebrae

> conjunctival epithelium> towards the limbus palpebralis posterior

> non-keratinized stratified squamous epithelium> close to the fornix conjunctivae

> stratified columnar epithelium> goblet cells in the surface layer

> conjunctival mucous secretion> accessory lacrimal glands (gll. lacrimales accessoriae)

> e.g. glands of Krause> in the vicinity of the superior conjunctival fornix

pars conjunctivalis

orbicularis oculi m.

tarsal plate

Meibomian glandexcretory duct

conjunctival epithelium

pars cutanea (skin)

gland of Zeisseyelash

pars cutanea

hair follicle

orbicularis oculi m.

tarsal plate

Meibomian gland (secretory acinus)

> limbus palpebralis anterior (anterior edge of the free margin of the eyelid)

> (in its vicinity)

> eyelashes (cilia)

> is devoid of arrector pili m.

> glands that open into the pilosebaceus duct of eyelashes

> glands of Zeiss

> ordinary sebaceous glands

> ciliary glands of Moll

> apocrine sweat gll.

> wide lumen

> simple colied tubules

> limbus palpebralis posterior (posterior edge of the free margin of the eyelid)

> (in its vicinity)

> tarsal glands of Meibom

> 12-30 glands in each eyelid

pars cutanea (cutaneous surface)

orbicularis oculi m.

hair follcicle

eccrine sweat gland

limbus palpebralis anterior

gland of Zeiss

eyelash

tubulo-alveolar gland> serous secretory portions (acini)

> lumens are wide> secration of tears

> watery fluid containing lysozyme> electrolites of similar concentration to the plasma> moistens and lubricates the eyeball and eyelids

> myoepithelial cells around> excretory duct

> dozen or more small ducts into the superior fornix> tears drain into the nasal cavity via the nasolacrimal duct

comparison of the lacrimal gland with other serous glandsthe lacrimal gland lacks the following items:

> intercalated tubules> striated ducts> centroaciner cells> islets of Langerhans

secretory portions excretory duct

plasma cell

lymphocytes