First of all, we investigated the origin, the construction and distribution of the bronchial arteries and veins in adult rabbits, and then observed various changes of the blood vessels in experimental cavities and
caseous foci and also studied the effects of streptomycin and isoniazide on the blood vessels of the cavity wall. The summary findings of the present experiments are described in the following. 1) In ten out of the fifteen rabbits emloyed, the bronchial artery originates from the right supreme intercostal artery; in three cases, in addition to this origin, it originates also from the left supreme intercostal artery; and in another case from the intercostal thoracic artery; while in the remaining one from the arc of the aorta. 2) The bronchial veins are divided into the extra-pulmonary and the intra-pulmonary veins. The former arises from the submucous blood vessels
located in the proximal part of the third bronchus, and running along with the bronchial artery, finally empties into the superior Vena cava; while the latter, originating from the submucous capillaries in the distal part of the third bronchus, and after anastomosing with one another in
the capsule of the bronchus, is communicated with the pulmonary veins. 3) In the caseous foci, although blood vessels are obliterated, capillaries are newly formed around the main trunks of the pulmonary artery and vein as well as around their residual branches. 4) These caseous foci are supplied with arterial blood from the bronchial
arteries, the blood vessels in the bronchial wall, and the newlyformed vessels of pulmonary arterial origin. 5) The capillaries in the cavity wall are classified into three types according to their origins; namely, Type I, those regenerating from fine branches of the pulmonary vessels; Type Ⅱ, those regenerating from the main trunk of the pulmonary vessels; and Type Ⅲ, those regenerating from the bronchial artery situated in the orifice of the drainage
bronchus. 6) The tuberculous cavities only in the orifice of the drainage bronchus receive an abundant supply of arterial blood directly from the bronchial artery, but those in other regions receive a scanty blood supply indirectly from the anastomoses between the bronchial artery, its sister vessels and the pulmonary artery. 7) The regeneration of blood vessels in tuberculous foci has been confirmed to occur not only in the bronchial artery and its sister blood vessels but also in the pulmonary artery and vein as well. 8) The constructions of blood vessels in the cavities treated with streptomycin or isoniazide present no significant difference from those of
the control. 9) The regeneration of blood vessels and hyperemia in the cavity wall of the cases treated with streptomycin present no significant difference from those observed in the control, but the cases treated with isoniazide show marked hyperemia, newly-formed vessels, and occasional bleedings.</p
