The stages of the tuberculosis lesion:

1-action of polymorphonuclear:

it takes place instead of penetration of microbes by active phagocytes of B.K. these latter protected by their waxy shell are not digested but their penetration is delayed.

2-more important action of blood monocytes:

They mobilize all of them to digest the B.K hence the formation of:

-giant cells: the monocytes fuse together in large cells called "giant cells" or recognizes several nuclei and B.K phagocytes or in the process of digestion.

Tubers: giant cells surrounded by lymphocytes group together by serving a jelly rich in living B.K called casium.

3-becoming of tuberculosis:

The casium may not be evacuated, the tuberculosis foci are still "closed" and the patient is not yet contagious.

- the caseous material can soften and then be eliminated by a branch draining the bacilli in very large numbers and constituting the sputum.

The tuber emptied of its contents gives way to a cavity (pulmonary cavity) which can gradually destroy the pulmonary tissue.