Murine Coccidioidomycosis-Reproductive Cycle of Spherule and Tissue Responses
1982 年 23 巻 4 号 p. 287-296
詳細
1982 年 23 巻 4 号 p. 287-296
This experiment deals with the reproductive cycle of spherules in vivo and the tissue responses to C. immitis infection. Ten congenitally athymic nude (nu/nu) mice were used for the study of the reproductive cycle of the spherule and 16 Swiss white mice, for the study of the tissue responses to the fungal infection. Each nu/nu mouse was inoculated intraperitoneally with 105 arthroconidia and two mice were sacrificed 2, 4, 8, 10 and 12 days after inoculation. On the other hand, each Swiss white mouse was infected intravenously with 5×104 arthroconidia and two mice were sacrificed 1, 2, 4, 6, 8, 10, 14 and 18 days after inoculation. Then, histopathologic sections were prepared from various internal organs. Arthroconidia transformed to spherules within 4 days. Young spherules before cleavage consisted of two zones. The protoplasm was distributed peripherally and formed the outer zone. The inner zone was stained positively by PAS. With the start of cleavage in the protoplasm, the PAS-positive substance disappeared and a vacuole appeared. Cleavage furrows occurred from the wall of the spherule, grew inward and ramified, and the protoplasm was divided into small masses (cleavage partitions) containing nuclei. Then, an outline of endospores began to appear in each cleavage partitions and clusters of the endospores were formed. Through these processes spherules were filled with uninucleate endospores. With the rupture of the wall of the spherule these endospores were released and the same reproductive cycle repeated in the tissue. In the Swiss white mice inoculated intravenously with the fungus the liver, lung and spleen were severely affected. Concerning the tissue responses to the fungal infection a marked purulent inflammatory reaction occurred when the reproductive cycle of the spherule progressed actively. On the other hand, when its reproductive activity declined, mononuclear cells began to accumulate at the foci and changed the histopathologic characters from pyogenic to granulomatous.
