Transmission electron microscopy. Chlamydia muridarum, lung, NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mouse. (a) Numerous extracellular (arrowhead) and intraepithelial (arrow) Chlamydia elementary and reticulate bodies. Scale bar = 2 μm. (b) Higher magnification of extracellular elementary bodies (arrow), measuring 200 to 300 nm in diameter, and reticulate bodies (arrowhead), measuring 500 to 700 nm in diameter. Scale bar = 500 nm. (c) Higher magnification of elementary bodies (arrows), measuring 200 to 300 nm in diameter, and reticulate bodies (arrowhead), measuring 500 to 700 nm in diameter, expanding the cytoplasm of an epithelial cell. Scale bar = 500 nm.