Uptake of Small Resin Particles (1–5µ Diameter) by the Alimentary Canal of the Calf

Abstract

THE intact skin and mucous membranes of the healthy body appear to present an impenetrable barrier to the entrance of particulate material, but yet bacteria are able to enter. How they do so is unknown. The tonsil is thought to be a vulnerable site : Mycobacterium tuberculosis has been shown to enter here¹, and even carmine granules dusted on to the tonsils before surgical removal penetrated very rapidly into the connective tissues². The wall of the small intestine is also permeable to bacteria ; coliform organisms³, M. tuberculosis ¹ and Salmonellae ⁴ have been shown to pass through the apparently intact mucous membrane and spread to the mesenteric lymph nodes, the blood, liver and spleen. More recently, at this Station, we have found that Mycobacterium johnei is also capable of rapid and extensive invasion of the body after the administration of an oral dose of culture to calves (Payne, J. M., and Rankin, J. D., unpublished work).