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Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms and all angiosperms. Plants with heterosporous life cycles using microspores and megaspores arose independently in several plant groups during the Devonian period. [ 2 ]
Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores . Generally speaking, the megaspore, or large spore, germinates into a female gametophyte , which produces egg cells .
Microspores: Produced sexually through meiosis, and give rise to a male gametophyte: Pollen in seed plants In plants, microspores, and in some cases megaspores, are formed from all four products of meiosis. Megaspores (macrospores) Produced sexually through meiosis, and give rise to a female gametophyte: Ovule in seed plants
Spores of two distinct sizes (heterospory or anisospory): larger megaspores and smaller microspores. When the two kinds of spore are produced in different kinds of sporangia, these are called megasporangia and microsporangia. A megaspore often (but not always) develops at the expense of the other three cells resulting from meiosis, which abort.
A female pinecone produces the megaspores of this heterosporic plant. A male pinecone produces the microspores of this heterosporic plant. Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female.
Among the things scientists have been looking at recently are the genetic differences of dogs living near in the Chernobyl Exclusion Zone (CEZ) near Pripyat in Ukraine, and a new study has been ...
Research has shown that dogs fed a meat-based whole-food diet have lower levels of compounds associated with increased inflammation and skin diseases in dogs (3).
Radiation-induced mutations may not be the reason for the genetic differences between dog populations living near the Chernobyl nuclear power plant, according to a new study.. The study, published ...