THE EYELIDS 603 



character to that of the conjunctiva, the derma of the cutaneous 

 surface being continuous with the submucous connective tissue of 

 this membrane. At the inner angle also, are the openings of the 

 peculiar large sebaceous glands, the tarsal glands of Meibom, their 

 orifices forming a continuous punctate row of pores barely visible 

 to the naked eye. 



The Meibomian glands are long compound saccular glands 

 whose secreting saccules open into a common, axially placed duct 

 which extends the whole length of the gland. Each saccule is 

 filled with cells in various stages of fatty degeneration and is 

 exactly similar in structure to the saccules of the ordinary seba- 

 ceous glands. The glands are embedded in the connective tissue 

 of the conjunctiva and are so large as to form projecting ridges on 

 its surface, which are disposed in vertical lines radiating from the 

 row of glandular orifices at the margin of the lid. At their blind 

 extremities the glands are often slightly bent or curved upon them- 

 selves, and this portion is embedded in a dense mass of fibrous tis- 

 sue known as the tarsus. 



The tarsus in each eyelid forms a very dense plate-like mass of 

 areolar connective tissue which is so dense and resistant as to erro- 

 neously suggest a cartilaginous structure. It is inserted between 

 the conjunctiva and the orbicularis muscle. It is thickest toward 

 the free margin of the lid, but becomes progressively thinner in 

 the opposite direction, until, as a mere fibrous membrane, the 

 palpebral fascia, it is continued, to the margin of the orbit. 



The conjunctival portion of the lids, the palpebral conjunctiva, 

 consists of a peculiar stratified epithelium and a thin connective 

 tissue corium. Its epithelium comprises four or five layers of cells, 

 the deeper of which are small and spheroidal, and the superficial 

 elongated or conical, their blunt ends forming the free surface of 

 the conjunctiva, their pointed extremities buried between the cells 

 of the deeper layers. The bases of these elongated cells become 

 somewhat expanded and broader from the increased tension of the 

 conjunctiva when the lids are closed ; they retract and become 

 narrower when the lids are separated and the conjunctiva relaxed. 



The cells of the superficial layer are often so distinctly elon- 

 gated as to possess a columnar form. They may, however, be 

 spheroidal or even somewhat flattened, in which case they very 

 closely resemble the ordinary type of stratified squamous epithelium. 

 The epithelial layer rests almost directly upon the connective tis- 

 sue corium, the basement membrane being imperfectly developed. 



