Ascus wall layer
ascus wall layer (noun,ascus term, pl. ascus wall layers) – the differentiation of the ascus wall as observed by transmission electron microscopy (TEM). The ascus is typically covered on the outside by a gelatinous layer (gelin, g-layer) forming a fuzzy coat. The wall itself is further differentiated from the outside towards the inside into at least three main layers, named a-, b-, and c-layer. Some asci also have a fourth inner layer, the d-layer. This d-layer is often further differentiated throughout the tholus. For example, tholus flanks (the bourrelet) are sometimes formed by the d2-layer; the central cone (or apical cushion) is formed by the d1-layer; an axial mass is formed by an apical swelling of the c-layer. These ultrastructural wall layers are not identical with the functional layers (tunicae) that form exo– and endoascus. Related terms: exoascus, exotunica, expansible inner layer, fuzzy coat, gelin, tunica, tunicle, endoascus, ascoplasm. This is:part of ascus.