cotyledon

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cotyledon

 [kot″ĭ-le´don]
1. any subdivision of the uterine surface of the placenta.
2. irregular convex areas on the chorionic surface of the placenta, consisting of two or more stem villi and their many branch villi; by the end of the fourth month the decidua basalis is almost entirely replaced by the cotyledons.

cot·y·le·don

(kot'i-lē'don),
1.
2. In plants, a seed leaf, the first leaf to grow from a seed.
3. A placental unit.
[G. kotylēdon, any cup-shaped hollow]

cotyledon

(kŏt′l-ēd′n)
n.
1. Botany A leaf of the embryo of a seed plant, which upon germination either remains in the seed or emerges, enlarges, and becomes green. Also called seed leaf.
2. Anatomy One of the lobules constituting the uterine side of the mammalian placenta, consisting mainly of a rounded mass of villi.

cot′y·le′don·ar′y (-ēd′n-ĕr′ē), cot′y·le′don·al (-ēd′n-əl)(-ēd′n-əs), cot′y·le′do·nous (-ēd′n-əs) adj.

cot·y·le·don

(kot'i-lē'dŏn)
1. In plants, a seed leaf, the first leaf to grow from a seed.
2. Irregular convex area of the fetal part of the placenta composed of stem villi.
[G. kotylēdon, any cup-shaped hollow]

cotyledon

  1. a part of the plant embryo in the form of a specialized seed leaf that can be thin and papery, as in the castor oil plant, or can act as a storage organ, as in the broad bean, absorbing food from the endosperm. Sometimes it also functions as a leaf after EPIGEAL germination, as in the runner bean. Some ANGIOSPERMS have one cotyledon per seed (MONOCOTYLEDONS) while others have two (DICOTYLEDONS).
  2. a part of the mammalian placenta on which a tuft of villi occurs, particularly in ruminants.