Aqueous outflow in the beagle. II. Postnatal morphologic development of the iridocorneal angle: corneoscleral trabecular meshwork and angular aqueous plexus.

The morphology and postnatal ontogeny of the major pathway for aqueous outflow in the canine eye has been examined. Normal canine chamber angles of the Beagle at one day, one through ten weeks, three, four and six months, and one and two years of age were used. Angle tissue was prepared and examined by standard techniques for light and electron microscopy. At birth the corneoscleral trabecular meshwork largely consisted of spongy mesenchyme. By the end of the first month the corneoscleral trabecular meshwork developed into a series of longitudinally oriented sheets anteriorly covered by the peripheral extremity of the corneal endothelium. The angular aqueous plexus (trabecular veins), which was formed at birth, was continually separated from the corneoscleral meshwork by an endothelial lining. Transcellular channels interconnected the trabecular veins and the corneoscleral trabecular meshwork. The corneoscleral trabecular meshwork and angular aqueous plexus in the canine angle are similar topographically, structurally and ultrastructurally to that described in other nonprimate and primate angles.