Fig. 23. Synchronous pressure-dependent cytoplasm and nucleus deformation enabled by tethering.

(A) Images are from transmission electron microscopy following in vivo fixation at an intraocular pressure (IOP) of 25 mm Hg with normal episcleral venous pressure (EVP). Schlemm’s canal (SC) endothelial cell cytoplasmic projections (arrowheads) join cytoplasmic processes of subendothelial cells (sec) bodies in the subendothelial space (SES). The terms subendothelial cell and juxtacanalicular cell are synonyms. The terms subendothelial space and juxtacanalicular space are also synonyms. Nuclei and cytoplasm of the SC endothelial cells distend into the SC lumen. The periphery of these distended, flattened nuclei taper (arrows). Nuclei frequently deform into a hollow-hemisphere shape and are tilted into many planes, resulting in frontal sections as illustrated by the plane through AB in the lower-left panel. A corresponding section (AB) in the upper right panel is a cylindrical nuclear profile surrounding the subendothelial space. The hollow circular nuclear profile is analogous to the appearance in the areas of cytoplasm that are referred to as “giant vacuoles.” Cytoplasmic processes originating beneath the nucleus of the endothelial cells join cone-shaped nuclear projections that appear as an inverted triangle in cross-sections (np). A cytoplasmic process from an endothelial cell (cpe) traverses the subendothelial space to join a cytoplasmic process (cps) of a subendothelial cell. f. 4650.) Tissue source: Primate, Macaca mulatto. (B) SC inner wall endothelial lining mirrors the appearance seen in the lower panel of (A). It illustrates the cytoplasmic processes that tether SC endothelium to the trabecular lamellae (TL) through cytoplasmic process connections of subendothelial cells. (A) from Johnstone M, Pressure-dependent changes in Nuclei, Ophthalmol. & Vis. Sci. 18, 44–51, 1979. Illustration from Johnstone Glaucoma Lab, University of Washington.