The arrangement of collagen fibrils in the iridescent cornea of the scorpion fish, Taurulus (Cottus) bubalis, and the transparency of vertebrate corneal stroma.

The iridescent layer in the corneal stroma of the scorpion fish, Taurulus (Cottus) bubalis (Scorpaeniformes), is composed of alternating thin lamellae of normal stroma containing collagen fibrils and lamellae of an amorphous dense-staining material. 2. Iridescence is lost after conventional resin embedding procedures, but is retained after embedding in urea-glutaraldehyde polymer. 3. The retention of iridescence and the absence of gross thickness changes during embedding in urea-glutaraldehyde polymer are an indication that the fine structure of the cornea is less altered than by conventional resin embedding. 4. It is believed that in life the collagen fibrils in the cornea of the scorpion fish and the cornea of the frog and rabbit are slightly larger and much more closely packed than is revealed by conventional resin-embedded sections.