A descriptive and quantitative study of the keratocytes of the corneal stroma of albino rabbits using transmission electron microscopy

The present morphometric study was designed to assess the dimensions and shape of keratocytes and their nuclei by transmission electron microscopy, and to assess these features in relation to the stromal lamellae. Corneas from 10 albino rabbits were fixed in 2% glutaraldehyde in cacodylate buffer (pH 7.4, 300 mOsm/kg) and embedded in Spurr's epoxy resin. Both transverse and coronal thin sections through the corneal stroma were prepared. The stromal lamellae had an average thickness of 2.45+/-1.15 microm. The average cell thickness of the keratocytes was 1.34+/-0.46 microm (range 0.49-4.76 microm), with the apparent cell thickness being related to the average anterior-posterior thickness of the adjacent lamellae (r = 0.424, P = 0.001)). The relative length and thickness of the cell nucleus, in transverse section, was measured to be 0.65+/-0.13 and 0.76+/-0.10 of the cell body section respectively. As assessed by planimetry, the area of the keratocyte cell body viewed in coronal section was 292+/-118 microm2, with a nucleus-to-cytoplasm ratio of 0.437+/-0.295. The electron micrographs confirmed the presence of gap junctions between keratocyte cell processes, and the occasional presence of centrioles in the cells. Some keratocyte processes were observed to extend from one face of the lamellae to the other, suggesting anterior-to-posterior cell communication. These studies indicate that the keratocyte cell thickness is influenced by the physical pressure exerted by adjacent stromal lamellae. The cell nucleus, while a dominant feature in transverse section, has a normal size in relation to the cell cytoplasm when viewed in coronal section.