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The fungi Saccharomyces produces ascospores when grown on V-8 medium, acetate ascospore agar, or Gorodkowa medium. These ascospores are globose and located in asci. Each ascus contains one to four ascospores. The asci do not rupture at maturity. Ascospores are stained with Kinyoun stain and ascospore stain.
Eight ascospores (green) are typically present in each ascus. Bitunicate asci in the pseudothecium of Leptosphaerulina sp. This is similar to a perithecium, but the asci are not regularly organised into a hymenium and they are bitunicate , having a double wall that expands when it takes up water and shoots the enclosed spores out suddenly to ...
The asci contain about 8 ascospores, are clavate-shaped (thicker at the apex) and are unitunicate, meaning they are single-walled. [3] The asci become costate (ribbed) after bursting of the perithecium, a process known as dehiscence. [3] The ascus tip possesses a thick, double-apical ring and lacks a sub-apical globulus. [3]
Upon opening of the ascus, ascospores may be dispersed by the wind, while in some cases the spores are forcibly ejected form the ascus; certain species have evolved spore cannons, which can eject ascospores up to 30 cm. away. When the spores reach a suitable substrate, they germinate, form new hyphae, which restarts the fungal life cycle.
In a mature ascus containing 8 ascospores, pairs of adjacent spores are identical in genetic constitution, since the last division is mitotic, and since the ascospores are contained in the ascus sac that holds them in a definite order determined by the direction of nuclear segregations during meiosis.
In a mature ascus containing eight ascospores, pairs of adjacent spores are identical in genetic constitution, since the last division is mitotic, and since the ascospores are contained in the ascus sac that holds them in a definite order determined by the direction of nuclear segregations during meiosis.
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The asci have walls composed of two to four layers of flattened cells which in total amount to 4–6 μm in thickness. There are eight ascospores contained within each ascus in A. fulvescens colonies. The ellipsoidal ascospores are a light brown colour and are either lens shaped or disc shaped. They can be as large as 5 x 3.5 μm and have ...