Ascospores are formed in ascus under optimal conditions. Typically, a single ascus will contain eight ascospores (or octad). The eight spores are produced by meiosis followed by a mitotic division.
Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division.
In ascomycetes the spores are produced within microscopic cells called asci. The asci vary in shape from cylindric to spherical. Commonly, each ascus holds eight spores - but there are species with just one spore per ascus and others with over a hundred spores per ascus.
The ascomycetous fungi produce prodigious amounts of spores through both asexual and sexual reproduction. Their sexual spores (ascospores) develop within tubular sacs called asci that act as small water cannons and expel the spores into the air.
The budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe have four ascospores in each ascus.
Sporulation of the baker's yeast Saccharomyces cerevisiae is a response to nutrient depletion that allows a single diploid cell to give rise to four stress-resistant haploid spores. The formation of these spores requires a coordinated reorganization of cellular architecture.
In the case of yeasts, a single cell converts to an ascus.
ASCUS ~ Atypical squamous cells of undetermined significance This diagnosis means that some of the cells on your Pap smear did not look entirely normal but did not meet diagnostic criteria for a lesion.
Ascus is a spherical, cylindrical or dub-shaped structure in which fusion of haploid nuclei occurs during sexual reproduction, followed by reduction division and formation of usually eight haploid ascospores. While ascocarp is a general term for the fruiting body of an ascomycete fungus.
Typically, a single ascus contains eight ascospores. Two meiotic divisions make the original diploid zygote nucleus into four haploid ones. And each of the four products of meiosis further undergoes a mitotic division that results in an octad of eight ascospores within each of the ascus.
Three nuclear divisions are required in the production of an ascus containing eight ascospores from a diploid zygote. Meiosis I and II result in the production of the first four haploid nuclei from the diploid zygote. The eight ascospore nuclei arise from mitosis, the third division.
Ascospores are a type of mold that typically develops during the winter on fallen, dead leaves that were previously infested. When it rains, it triggers the release spores in the air. You can find this type of mold practically anywhere, but indoors it will start growing on moist materials.