ABSTRACT
Using a transmission electron microscope, the authors investigated the developmental cycle of Chlamydia trachomatis, serotype L2 in McCoy cells. The cell monolayer was examined closely after inoculation with the laboratory strain and subsequently after intervals of 5, 10, 15, 20 and 30 hours. Soon after inoculation the authors observed attachment of elementary bodies to the cell surface and their penetration into the cytoplasm. The transformation of the elementary body into a reticular one occurred via an intermediate body and was completed within 10 hours after inoculation. By division of reticular bodies an intracytoplasmic inclusion developed which attained 20 hours after inoculation the size of a cell nucleus. After a 30-hours interval the inclusion filled practically the whole cell and contained in addition to the elementary body also reticular and intermediate bodies.
