Electron micrograph (EM) of an isogenous nest in hyaline cartilage. Cartilage matrix surrounds a pair of chondrocytes. Each cell has a single nucleus (Nu) and an irregular cell border with short, stubby foot-like extensions (arrows) of plasma membrane. The cytoplasm has abundant RER with both flattened and dilated (*) cisternae. Surrounding extracellular matrix has a finely fibrillar appearance. 35,000×. (Courtesy of Dr B. J. Crawford)