Abstract
Abstract: :
Purpose: To investigate by means of scanning electron microscopy (SEM) interlacing of collagen lamellae in the mid-stroma of the human cornea after opening the interlamellar spaces. Method: For SEM, cells and non-collagenous extracellular matrix were removed with 10% sodium hydroxide. Specimens were dehydrated in a series of graded tertiary butanols, frozen at -24°C and dried in an exsiccator by sublimation of the frozen butanol. Dried corneas were cut vertically with a razor interlamellar spaces were exposed by stretching the stroma along its anterior-posterior axis by pulling apart the inner (endothelial) and outer (epithelial) edges. Specimens were sputtered with gold and examined with a Cambridge Stereoscan 90 microscope. Results: The opened interlamellar spaces gave the stroma at the cutting edge the appearence of a polymorphic honeycomb. The stromal openings differed in size, from about 10µm to over 150µm length and up to 80µm in height. Adjacent lamellae remained connected at several interconnecting regions, either through an exchange of short merging sub-lamella or single fibrils. Interlacing lamellae crossed through fissures between the branches of splitting lamellae. Others crossed clefts of neighbouring lamellae, and other lamellae tunnelled crosswise through a horizontally split lamellae hanging in the inferior branch as in a hammock. Large interweaving zones in which a mixture of several types of interlacing was localized close together could also be found. Conclusion: The present study indicates that interlacing is a distinct and important feature of the human cornea, and it gives new insights into the stromal morphology by demonstrating the various types of interlacing that occur between collagen lamellae.
Keywords: 370 cornea: basic science • 374 cornea: stroma and keratocytes • 472 microscopy: electron microscopy