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sively invade more and more anterior lamellae (Laguesse, 1923b). As the
stromal fibroblasts invade their long axes come to lie parallel to the
fibrils of the layer in which they locate. In sections in the plane of the
FIG. 4. Section of tadpole cornea in a plane normal to the corneal surface. The
anterior epithelium is in the upper left corner and the posterior epithelium is in the
lower right corner. The lamellae are composed of parallel arrays of collagen fibrils whose
crossbands are in register across the lamella. The gradual shift in orientation of the
fibrils in successive lamellae as the stroma is traversed is clearly demonstrated. (Courtesy of Dr. Marie Jakus.)
stroma the fibroblasts are, as a consequence, disposed in two populations whose cells have their long axes at right angles to one another. The
collagen which is synthesized by the fibroblasts polymerizes to form
fibrils. The parallel groups of fibrils constitute fibers which enlarge in
diameter by the addition of more fibrils until they coalesce with other
fibers in the same layer which are parallel to them. In this manner
lamellae are formed. While there may be crossing over of fibrils at the