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Introduction to Clinical Mycology

Part 2

Fungi: Morphology of Yeasts

Slide 19

January 2012

We have another group of fungi that we deal with in the clinical laboratory and these are the yeasts. The yeasts primarily are made up of budding cells called blastoconidia. Blasto means bud and conidia means spore. Some of these yeasts produce pseudohyphae and true hyphae. We know true hyphae are these filaments that look like garden hoses. Pseudohyphae are nothing more than yeast cells that have elongated and remained attached to each other and they look almost like a hyphal strand except that where the yeast have elongated the ends are rounded. And you will notice that it is not one big long filament, it is made up of a number of the elongated cells that have rounded ends that are still attached to each other. They look like links of sausages. Ascospores are produced by some of the yeasts and you could use special stains like the acid pas stains to be able to show those if you need to do that. Most of the yeasts produce creamy bacterial-like colonies. If you grow yeast in the laboratory, you know there it will smell almost like a bakery. The yeasts are very important to agriculture. They are very important in the baking and brewing industry but they are also very important in the clinical setting because they do cause human disease and lots of problems from immunocompromised patients. Some of the fungi are dimorphic in that they produce yeast in the tissue or at 35 to 37 degrees centigrade in the laboratory under the right conditions that you would have to supply.

Fungi: Morphology of Yeasts


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