Structure and composition of Bowman's membrane. Study by frozen resin cracking

Bowman's membrane, seen as a homogeneous layer in light microscopy, is demonstrated by transmission electron microscopy as a layer with fibrils in random distribution, for which reason the term used at present is Bowman's layer. Frozen resin cracking demonstrates that the fibrils of the layer run in certain patterns and lie in 3 or 4 strata in the central areas of the cornea. In the periphery, stratification is scarcely demonstrable. The fibrils consist of collagen inseparable by histochemical methods from the collagen in the stroma, but the diameter is only half or two-thirds of the diameter of the stromal fibrils. The authors discuss the possibility that artifacts are responsible for the findings. However, an explanation of the results may be that Bowman's layer is a condensation of the superficial layers of the stroma resulting from the development of the layer. The fibrils are presumed to break in different ways, but apparently in layers in which the breaking strengths are identical.