placentation

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Related to axile placentation: parietal placentation

placentation

 [plas″en-ta´shun]
the series of events following implantation of the embryo and leading to development of the placenta.

plac·en·ta·tion

(plas'en-tā'shŭn),
The structural organization and mode of attachment of fetal to maternal tissues in the formation of the placenta. Types of placentation are defined under placenta.

placentation

/pla·cen·ta·tion/ (pla″sen-ta´shun) the series of events following implantation of the embryo and leading to development of the placenta.

placentation

(plăs′ən-tā′shən)
n.
a. Formation of a placenta in the uterus.
b. The type or structure of a placenta.

placentation

Obstetrics The formation of the placenta in the uterus; the process by which a placenta grows and develops in the uterus. See Extrachorial placentation.

plac·en·ta·tion

(plas'en-tā'shŭn)
The structural organization and mode of attachment of fetal to maternal tissues in the formation of the placenta.

placentation

the arrangement of PLACENTAS (2) in the plant ovary, which can be classified into several categories including:
  1. (a) apical, at the ovary apex,
  2. (b) basal, at the ovary base,
  3. (c) parietal, on the ovary wall,
  4. (d) free-central, on a column growing up from the ovary base.

placentation

1. the series of events following implantation of the embryo and leading to development of the placenta.
2. the nature of the implantation. See also placenta.

adventitial placentation
developmental of additional areas outside the normal areas, e.g. intercotyledonary in cattle.
cotyledonary placentation
the areas of placentation are limited to caruncles, approximately circular masses scattered over the placenta. Characteristic of the cow, ewe and goat doe.
diffuse placentation
the whole of the surface of the chorion is placental.
intercotyledonary placentation
abnormal placental attachments between the cotyledons, in cows.
zonal placentation
only some zones of the placenta have a vascular area involved in placentation. Characteristic of the bitch and the queen.
Enlarge picture
Zonary placenta of carnivores. By permission from Sack W, Wensing CJG, Dyce KM, Textbook of Veterinary Anatomy, Saunders, 2002
References in periodicals archive ?
The extinct Minsterocarpum alatum Reid and Chandler (1933) from early Eocene beds at Sheppey, England is a four to six-loculed capsule, 16-22 mm long, with axile placentation and numerous seeds arranged in two rows in each locule.
The ovary is superior with axile placentation and is 4-6-carpellate; each carpel is subdivided by a partial secondary septum.
Ovary 4-10-locular, with axile placentation and only 1 to few ovules per locule, superior, sometimes with fleshy papillae; style continuous with the ovary; stigma truncate.
Ovary (4-)5-locular, with axile placentation, superior; style impressed; stigma truncate.
Ovary 1-14-locular, with axile placentation, superior; style gradually tapered or impressed; stigma truncate, capitate, peltate, cup shaped, funnel shaped, or strongly lobed, considerably enlarged in wind pollinated species.
Ovary (l-)4(-8)-locular, with axile placentation, superior; style gradually tapered or impressed; stigma truncate, capitate, peltate, cup shaped, funnel shaped, or strongly 4-lobed, considerably enlarged in wind pollinated species.