Normal anatomy of the aqueous humour outflow system in the domestic pig eye.

The normal functional anatomy of the aqueous humour outflow pathways in the domestic pig is poorly documented in the literature despite its being readily available and of a similar size to the human eye. Anterior segment tissue from 12 pig eyes was appropriately fixed and investigated by light microscopy, and scanning and transmission electron microscopy. The configuration of the iridocorneal angle tissues is similar to other nonprimate mammals in several respects, i.e. it possesses a deep ciliary cleft crossed by stout pectinate ligaments and delicate uveal cords, poorly developed ciliary musculature, and an angular aqueous plexus. However, there were some noteworthy features which may make it a suitable model for specific types of glaucoma related research. These features include a shallow scleral sulcus which contains a wedge-shaped mass of corneoscleral tissue comparable in size to the human trabecular meshwork. This tissue was more trabecular than 'reticular' in arrangement, the latter being the more common in nonprimate mammalian species. The relevance of the present findings to the use and limitations of the porcine eye as a model of the human aqueous outflow pathways is discussed.