Eyelids are skin folds, which can be actively moved. They consist of a tough connective tissue skeleton H (tarsus superior and tarsus inferior). Toward the outside, it is covered by the musculus orbicularis oculi (pars palpebralis) [2. The surface covering of the eyelid is a multilayered keratinizing squamous epithelium with only a few velum hairs. The outer lid is about 2 mm wide and consists of a dull anterior [4 and a sharp-edged posterior palpebral limb O. This tissue continues in the multilayered nonkeratinizing squamous epithelium of the palpebral part of the conjunctiva (conjunctiva tarsi) 0 .A multi-layered columnar epithelium with goblet cells is only found beyond the level of the fornix of the conjunctiva. Long cilia (eyelashes) C3 protrude from the anterior rim of the lid. They are rooted in the lid plate (see Fig. 626). The sebaceous glands (Zeis glands), apocrine scent glands and the sweat glands of the cilia (Mollglands) end in the hair follicle of the eyelashes. The right side of the figure shows numerous tarsal holocrine sebaceous glands (Meibomian glands) ffl with long secretory ducts that end on the anterior edge of the lid (posterior limbus). The tight tarsal fiber meshwork envelops the lobed glands. Smooth muscle cells run both before and behind the Meibomian glands at the rim of the lid. The palpebral part of the musculus orbicularis oculi [2 is located in front of the tarsus. The subcutaneous tissue of the lid consists of loosely structured, cell-rich connective tissue O, which is usually free of adipose tissue. The epithelium on the anterior eyelid is thin. The skin of the lids contains many melanocytes. This explains the dark pigmentation.
2 Palpebral part of the orbicularis oculi muscle
4 Anterior palpebral limb
5 Posterior palpebral limb
6 Palpebral part of the conjunctiva
8 Tarsal glands, Meibomian glands
9 Loosely structured subcutaneous connective tissue
10 Deep skin fold ofthe upper lid
11 Chalazion (infection of the Meibomian gland)
Stain: hematoxylin-eosin; magnifying glass
Detail magnification of an upper eyelid, with the rim of the lid and eyelashes. The following structures are shown:
2 Hair funnel
3 Hair shaft, scapus pili of the eyelash
5 Rim of the eyelid, multilayered keratinizing squamous epithelium
6 The terminal portions of a Meibomian gland end in the hair follicle clearance
8 Tarsus superior
10 Hair papilla
11 Subcutaneous tissue of the lids
Compare with Figs. 625-629. HeinrichJ. Meibom (1638-1700).
Stain: alum hematoxylin-eosin; magnification: x 10
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