Difference between revisions of "Tunica"

'''tunica''' ([[Category:Noun]][[:Category:Noun|noun]], [[Category:Ascus term]][[:Category:Ascus term|ascus term]], ''pl.'' tunicae; ''synonym:'' [[tunicle]]) – the functional layers of an [[ascus wall layer|ascus wall]]. Early classifications generally distinguished two types: [[unitunicate asci]] (with a single tunica, i. e., a wall that remains intact when [[ascospore]]s are released), and [[bitunicate asci]] (two tunicae, i. e., a wall separating into two layers during [[ascospore discharge]]). [[Ultrastructural]] studies have demonstrated that the situation is much more complex and several [[ascus wall layer]]s can be distinguished. The layers that form the [[exoascus|exo–]] and [[endoascus]], are structurally not generally composed by the same wall layers. Thus, the exoascus can be composed of the a- and b-layer, or the a-, b- and c-layer. Likewise, the endoascus may be composed of the c- and d-layer or of the d-layer alone. The terms unitunicate and bitunicate are therefore inappropriate to describe the ascus [[ultrastructure]], instead they refer to functional [[ascus type]]s. To emphasize that the ascus wall is not generally segregated into one or two layers, the terms [[exotunica|exo–]] and [[endotunica]] should be avoided. These terms suggest that the exo- and exoascus are structural layers, whereas they are clearly functional, i. e., frequently composed of different ultrastructural layers. ''This is:'' [[Category:Part of ascus]][[:Category:Part of ascus|part of ascus]].