Читать книгу Essentials of Veterinary Ophthalmology - Kirk N. Gelatt - Страница 40

Descemet's membrane is a PAS‐positive homogeneous, acellular membrane that is actually the basement membrane of the posterior endothelium. Descemet's membrane is produced throughout life, thus forming a thicker membrane as individuals age. Clinically, the membrane shows elasticity, but it contains only fine collagen fibrils. Descemet's membrane is normally under some tension and when ruptured it tends to curl like a scroll. Descemet's membrane ends at the apex of the trabecular meshwork in the limbal region. To some degree, its composition is similar to that of the trabeculae of the ICA. Ultrastructurally, Descemet's membrane is distinctly layered in most animals, usually having a relatively thin anterior, unbanded zone next to the stroma, followed by a broad‐banded zone and then by another broad, posterior unbanded zone located next to the endothelium. Healing and replacement of Descemet's membrane can result in duplication of this structure.

Figure 1.24 SEM of a four‐year‐old canine corneal endothelium reveals occasional variability in cell size (a) and the lateral surface interdigitations (arrows) between cells (b). The most prominent feature of the endothelial cell is the nucleus (N), which bulges slightly into the anterior chamber. (Original magnification: a, 960×; b, 3500×.)