An ultrastructural study of neuromuscular spindles in normal mice: with reference to mice and man infected with Mycobacterium leprae

Mycobacterium leprae have been found within muscle spindles in mice, using electron microscopy, and in man, using light microscopy. Their mode of entry clearly is important. It may be via capsular cells, capillaries or nerves. For this reason muscle spindles from normal mice were studied by electron microscopy with special reference to the capsule and the relationship of it with capillaries and nerves, as well as details of the intrafusal fibres and capsular space. A fenestrated capillary was found between the capsular cell layers and outside the capsule in one spindle and in another spindle both a fenestrated and a continuous type of a capillary were found between the capsular cells; this may be of interest for pharmacological studies. However, the muscle spindles of the mouse were in the main similar to muscle spindles studied by other workers in man and other mammals.