A comparative study of stromal swelling in sea lamprey spectacle and brook trout cornea

Abstract

Brook trout corneal stroma immersed in water increased to 350 % of its original wet weight; whereas, the stroma of sea lamprey spectacle which contains sutural fibers increased to only 150 %. The normal arrangement and spacing of collagen fibrils was preserved in the stroma of the sea lamprey spectacle. In contrast, in the osmotically swollen brook trout corneas, large interlamellar spaces were present which contained fragments of lysed keratocytes. Control stromal tissues from both sea lamprey spectacle and trout cornea placed in 0.5 % saline showed small changes in wet weight and maintenance of normal collagen alignment. The sutural fibers present in the sea lamprey spectacle appear to prevent stromal hydration by opposing the osmotic swelling of the stromal cells, thereby limiting the development of interlamellar spaces and preventing the loss of transparency.