Development of Tuberculous Infection. In vivo Observations in the Rabbit Ear Chamber.

Abstract

Microscopic observa-tions of early tuberculous infection in a rabbit ear chamber together with a modification of the chamber originated by San-dison are descr. The modified chamber is light weight, simpler and does not require the ear splints of previously descr. chambers. Four chambers were inoculated directly via removable plugs with Mycobacterium tuberculosis (Strain Rave-nel RV) and frequent observations made until the development of necrosis. The tissue response is descr. as an early and late reaction. The early reaction lasted 9 to 23 days and was minimal. The late reaction was sudden and progressive, began on the 10th to 24th day and resulted in complete necrosis of the observeable area by the 29th to 40th day. It started with marked sticking of WBC to vascular endothelium and considerable infiltration of WBC into the interstitial tissue. This was followed by progressive vascular dilatation, slowing of blood flow, hemoconcn., and eventual thrombosis. The first thrombi occurred in regions of heavy cellular infiltrate which became confluent by the end of the expt. Stained sections showed these areas to contain cellular debris, epithelioid cells, giant cells and innumerable acid-fast bacilli. In the only animal systematically skin-tested with tuberculin the late reaction began coincidentally with the development of skin hypersensitivity. A Kodachrome movie of the expt. has been made from which representative frames are included.