In vivo development of spores of Absidia ramosa.

Approximately 10(6) spores of Absidia ramosa were inoculated intravenously into normal and cortisone pretreated mice. At subsequent time intervals the liver, lungs and kidneys were removed and examined for fungal localization and growth. In normal mice, spore germination and continued hyphal growth was restricted to the kidneys-evidence of germination not being visible until around 30h post inoculation. Cortisone therapy allowed germination of spores in the lung and kidney by 7h but subsequent hyphal growth in the lung was severely restricted compared with the kidney where extensive hyphal growth occurred. Germination of spores in the liver of cortisone treated animals was slow, not becoming apparent until about 40h after inoculation. These results suggest that host defence mechanisms in the form of phagocytosis as well as biochemical inhibitors and/or lack of suitable stimulators are important in preventing germination of introduced fungal spores. Once germination has occurred, it appears that additional as yet undetermined factors play a role in allowing continued growth of the fungus.