Ultrastructure of the Interface between Descemet's Membrane and the Posterior Stroma

Abstract

Objective: To reveal the ultrastructural characteristics of the interface between Descemet's membrane (DM) and posterior stroma at different ages. Methods: In this experimental study, corneal buttons (n=14) were divided into three groups, infants (n=3, 0-6 years), adults (n=5, 21-48 years), and elderly (n=6, 63-87 years). Each corneal button was mounted on a suction block, and the endothelium was gently marked with an 8.0 mm trephine and then stained with trypan blue. Smooth forceps were used to strip off the DM from the mark at the central edge, exposing the first cleavage plane (CⅠ). Then half of the CⅠ was scraped to expose the second cleavage plane (CⅡ). Samples were observed by scanning electron microscopy and by hematoxylin-eosin (HE) staining and immunofluorescence staining for collagen types Ⅰ, Ⅲ, Ⅳ, Ⅴ and Ⅵ. Results: The CⅠ of all 14 donor corneas were smooth under light microscopy, while CⅡ were relatively rough. Scanning electron microscopy showed that the CⅠ (pre-DM membrane) was thin and smooth, while the CⅡ (posterior stroma) was composed of relatively rough stromal fiber bundles. HE staining showed that where DM was attached to the stroma, the smooth pre-DM membrane was exposed after stripping DM. Immunofluorescence microscopy showed that the pre-DM membrane was strongly positive for collagen type Ⅰ and Ⅲ. Collagen type Ⅵ was topical positive in the pre-DM membrane. There was no significant difference in three groups. Conclusions: A thin, smooth pre-DM membrane consisting of collagen type Ⅰ, Ⅲ, and Ⅵ was present at the DM-stromal interface in different ages. The pre-DM membrane was tightly attached to the stroma, but only loosely to DM. Key words: posterior stroma; Descemet's membrane; interface; pre-Descemet's membrane; ultrastructure