Search results
Results from the WOW.Com Content Network
Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or species can occur in numbers of one (e.g. Monosporascus cannonballus ), two, four, or multiples of four.
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 ...
The nuclei along with some cytoplasma become enclosed within membranes and a cell wall to give rise to ascospores that are aligned inside the ascus like peas in a pod. 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 ...
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 ...
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.
The nucleus of the ascus finally divides three times, producing the nuclei of the eight ascospores; which subsequently are formed by free cell formation. From the half-grown perithecium there arise hyphae which grow out as the appendages. These appendages serve to attach the perithecia to plants. [2]
Each ascus contains eight spores arranged in one to three rows. [7] The reproductive spores (ascospores) of O. papulosa are fusiform to clavate-oblong in shape, wider at one end and tapering at the other. They measure 18.5–26.5 μm in length and 5.6–9.6 μm in width.