[Ultrastructural studies on the pterygium. II. Connective tissue, vessels and nerves of the conjunctival part (author's transl)].

The stromal part of the pterygium is remarkably rich in plasma cells. The connective intercellular substance shows two different pathological modifications: A clotting together of collagen fibres to broad, osmiophilic, elastoid bands and a widening of the spaces containing the granular nonfibrillar ground-substance . The vascular system consists mostly of fenestrated sinusoid capillaries. Their endothelial cells frequently show degenerative changes and the basement membrane of the vessels can be as thick as up to 50--100 fold the normal size. For the first time nervous formations could be found in the pterygium. Axons of the autonomic system join the basal epithelial cells, where they form terminal endings. Encapsulated myelinated and nonmyelinated corpusles probably stem from the sensory nervous system.