Electron Microscopy of Young Candida albicans Chlamydospores

Abstract

One-to three-day-old cultures of Candida albicans bearing chlamydospores were grown and harvested by a special technique, free of agar, and prepared for ultramicrotomy and electron microscopy. These young chlamydospores exhibited a subcellular structure similar to that of the yeast phase, e.g., cytoplasmic membrane, ribosomes, and mitochondria. Other structural characteristics unique to chlamydospores were a very thick, layered cell wall, the outer layer of which was continuous with the outer layer of the suspensor cell wall and was covered by hair-like projections; membrane bound organelles; and large lipoid inclusions. Only young chlamydospores less than 3 to 4 days old exhibited these ultrastructural characteristics.

Chlamydospore formation in Candida albicans and Candida dubliniensis– an enigmatic developmental programme

“…In 14-day-old cultures the authors could neither detect mitochondria nor ribosomes in ultrathin sections of chlamydospores. 51 These latter findings may explain the failure of other investigators to observe germination of older chlamydospores (see below). Of interest was also the free lipid content of chlamydospores, which was determined to be 12% of the dry weight of chlamydospores and thus significantly higher than the approximately 5% reported for yeast cells.…”

“…Other investigators, however, depicted by electron microscopy that a remarkable portion of the total cell volume of chlamydospores appeared to be occupied by a large vacuole and cytoplasmic organelles similar to those observed in blastospores. 52 Interestingly, Miller et al [51] could demonstrate by electron microscopy that mitochondria and ribosomes were abundant in chlamydospores derived from 1-to 3-day-old cultures, but appeared to decrease in number in older chlamydospores. In 14-day-old cultures the authors could neither detect mitochondria nor ribosomes in ultrathin sections of chlamydospores.…”

“…Electron micrographs of thin sections of chlamydospores showed that the chlamydospore cell wall is double‐layered, consisting of a thin, electron‐transparent outer layer surrounding a thick electron‐dense inner layer 49–52 . The thickness of the inner layer increases with age and the overall thickness of the entire wall of mature chlamydospores is approximately 400 nm.…”

“…Interestingly, Miller et al [51] could demonstrate by electron microscopy that mitochondria and ribosomes were abundant in chlamydospores derived from 1‐ to 3‐day‐old cultures, but appeared to decrease in number in older chlamydospores. In 14‐day‐old cultures the authors could neither detect mitochondria nor ribosomes in ultrathin sections of chlamydospores 51 . These latter findings may explain the failure of other investigators to observe germination of older chlamydospores (see below).…”

The Chlamydospore of Candida albicans.

“…A number of papers has been written not only about the germination of csp, the production and staining behaviour of catenulate csps and suspensor cells but about their ultrastructure as well (1,2,7,10,11,12). The general opinion is that the csp is either a resting structure, or a storing structure, or a reproductive cell (2,3,14,15).…”