Figure 2
All images are from Bmp4+/- heterozygotes on the C57BL/6J background, except for G and I that are from normal mice. A-C. Slit-lamp photographs indicate phenotypic variability between individuals, but most eyes are similar to those shown in B and C. A. The eye is normal. B. There is central corneal haze, an abnormally large and irregular pupil, and an anterior subcapsular and cortical cataract. C. The cornea is hazy and the pupil is open and irregularly shaped. There is an anterior subcapsular cataract and inferiorly the peripheral cornea is opaque and vascularized. D. The iridocorneal angle is relatively normal at this location with an obvious Schlemm's canal (bounded by arrowheads), trabecular meshwork (asterisk) and ciliary body (CB). The cornea is scarred and vascularized (arrow). This corresponds to the inferior opacification in B. H&E x 200. E. SC is abnormally short (arrowhead) and the trabecular meshwork is absent. A broad anterior synechia covers the region where outflow structures are normally located. H&E x 200. F. The hypoplastic iris is directly attached to the termination of Descemet's membrane (arrow). SC and the trabecular meshwork are absent. The ciliary body is severely malformed with no ciliary processes (arrowheads). Fibrovascular tissue (white arrow) appears to have drawn pigmented ciliary epithelium posteriorly to form a pseudocyst (asterisk) filled with blood. Persistence of the anterior vascular tunic of the lens is obvious anterior to the lens capsule (LC). H&E x 200. G. A wild type C57BL/6J mouse has a normal posterior trabecular meshwork (between arrowheads) and SC. Several layers of trabecular beams are present. Collagen (arrow) and elastic tissue (white arrow) are abundant normal components of the trabecular meshwork. Original magnification x 14,000. H. In this Bmp4+/- heterozygote, posterior SC is lined by endothelium (arrow) and contains giant vacuoles (G). However, the trabecular meshwork is abnormally thin for this posterior location with only 1–2 trabecular beams (arrowheads) compared to the normal 7–10. Collagen fibers are decreased in number and elastic tissue is absent. In this posterior location, the iris (I) lies close to the meshwork. Original magnification x 12,000. I. Anterior trabecular meshwork of normal C57BL/6J mouse. SC is lined by endothelium. Extracellular matrix (arrows) is abundant in both the juxtacanalicular region just below SC and in the trabecular beams. There are 4–5 trabecular beams. Original magnification x 15,000. J. The anterior trabecular meshwork of Bmp4+/- heterozygote is hypoplastic and both the juxtacanalicular region and trabecular beams contain little extracellular matrix. Original magnification x15,000.