COCCIDIOIDES IMMITIS: CYTOLOGICAL STUDY ON THE FORMATION OF THE ARTHROSPORES

Abstract

Somatic nuclear division and the manner of arthrospore formation in saprophytic phase of Coccidioides immitis have been studied. Two distinct nuclear cycles, one occurring during the active growth in young hyphae and another occurring in old thin hyphae or during arthrospore formation, were observed. The first cycle consisted of several stages starting from round resting nuclei → ring stage → V stage → and filaments which divide longitudinally. The two daughter nuclear filaments reorganize into round nuclei. The second cycle is more simple than the first. The round resting nuclei become elongated and constricted at the middle, dividing vertically. The chromosome number appears to be 3. The metaphase plares or spindle apparatus were not seen.The fertile hyphae develop septa not basipetally but synchronously. Alternate cells, after being thus delimited, increase in size and in thickness of wall becoming spores while the intervening cells gradually lose cytoplasm. The nuclei remain, without cytoplasm, in the intervening cells until the adjacent spores are completely matured. The spores are released by fragmentation of the walls of the sterile segments. The relationship of C. immitis to the members of Gymnoascaceae has been discussed.