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matrotrophy
Matrotrophy is a form of maternal care during organism development in which the embryo of an animal or flowering plant is supplied with additional nutrition from the mother (e.g. through a placenta). This can be contrasted with lecithotrophy, in which the only source of nutrition for the embryo is yolk originally contained within its egg.
While commonly associated with vertebrates and especially mammals, matrotrophy occurs in 21 of 34 animal phyla.
In plants, matrotrophy is considered a critical evolutionary development preceding the origin of embryophytes and therefore essential to the evolution of land plants. Matrotrophy is facilitated by cytological and ultrastructural modifications on one or both sides of the generational junction, a region called the placenta. Specialization of the placental cells pertains further to their cytological and ultrastructural characteristics: the cytoplasm is often dense and rich in lipids, the vacuole is typically reduced but large in ''Sphagnum'', the endoplasmic reticulum extensive, mitochondria numerous and large, chloroplasts numerous, often less differentiated, rich in lipid-filled globuli and sometimes filled with starch.〔
==See also==
*Pregnancy (fish)
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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