[Ultrastructural studies on the pterygium. I. Epithelium and glands of the conjunctival part (author's transl)].

13 pterygia from patients aged between 39 and 81 years are studied by electron microscopy. The pterygium is covered by a multilayered, highly differentiated cylindrocellular epithelium. Arrangement and height of the microvilli of the superficial epithelial cells differ from those of the conjunctival epithelium. Morphological signs of secretion and resorption are found. As a characteristic the basal epithelial cells of the pterygium are rich in metaplasmatic filaments. Tubular glands are localised underneath the covering epithelium; they may reach the deep substantia propria. Their walls consist of a single layer of cylindrical cells. A varying number of goblet-cells are embedded between them. The secretion by the epithelial formations of the pterygium is of the merocrine, holocrine and microapocrine type.