Electron microscopic study of leprosy in a mangabey monkey (natural infection).

Ultrastructural features of the leproma of a) a naturally infected mangabey monkey, and lepromas and liver of b) a passage mangabey monkey, c) a rhesus monkey, d) an African green monkey, and e) a nine-banded armadillo inoculated with leprosy bacilli isolated from the leproma of a naturally infected mangabey monkey were studied by the freeze-etching technique. The size, shape, and ultrastructural features of leprosy bacilli in the phagolysosomes of macrophages in all of these samples were essentially the same as those in humans, nude mice, and armadillos inoculated with human Mycobacterium leprae. Distinct accumulations of small spherical droplets were observed around leprosy bacilli inside lepra cells of all the samples but were scarce in the specimen from the green monkey. The bacilli in all samples were long and slender, and had band structures on the smooth cell wall surfaces. The bacilli were indistinguishable from M. leprae.