Читать книгу Essentials of Veterinary Ophthalmology - Kirk N. Gelatt - Страница 54

Lining the anterior capsule is a monolayer of lens epithelial cells that continuously produce new basement membrane (i.e., capsule material). The cells are cuboidal to squamous axially at the anterior pole of the lens, become columnar near the equator, and then elongate into slender hexagonal lens fibers. Nuclei are lost as lens fibers mature and move centrally. The lens epithelium lines only the interior aspect of the anterior surface of the capsule postnatally. The cell apices face the outer lens fibers, being attached to the underlying cortical fibers by tight junctions (zonula occludens) and macula adherens. The posterior lens epithelium forms the embryonic primary lens fibers and, thus, is absent under the posterior lens capsule later in life.

Mature lens fibers become dependent on the anterior epithelium for maintaining a critical level of dehydration, which allows the soluble proteins to be functionally effective, and for providing a healthy level of reduced glutathione. The lens epithelium is highly susceptible to damage caused by factors such as changes in local oxygen concentration, exposure to toxins, X‐ray irradiation, and ultraviolet light damage.