Fig. 10. Stereopairs of 0.20 µm thick sections of gea1-6 mutant cells incubated for 40 minutes at 37°C. (A) Non-fenestrated ER sheets accumulate to form a broad network (ER) interconnecting the nuclear envelope and the subplasmalemmal ER. V, vacuole; N nucleus. Magnification x36,200. (B) Cylinders or spheres of unfenestrated membrane (arrowheads) are dispersed throughout the cytoplasm. Note the absence of tubular networks and secretory granules. N, nucleus. Magnification x35,600. (C) A small tubular network (arrow) is continuous on one side with an ER sheet seen in profile, and is continuous on the other side with a multi-layered cylindrical structure (arrowheads). A sheet of unfenestrated ER (ER) is seen in oblique view (bottom-right). N, nucleus. Magnification x55,600. (D) A cylindrical structure is made up of anastomosed ribbons of unfenestrated membrane (arrowheads). V, vacuole. Magnification x57,700.