placentation


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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 ?
Placenta percreta is one of the most devastating obstetric diseases associated with abnormal placentation.
30) See Furuya, "Pathophysiology of Placentation Abnormalities" 1301-2.
The region represents a complex structure of several polarized microenvironments controlled by sex steroid hormones, aggregates of leukocytes as local mediators to regulate sperm transport, implantation and menstruation, and in pregnancy to regulate interaction with interstitial and endovascular trophoblast invasion to achieve deep placentation.
First-trimester placentation and the risk of antepartum stillbirth.
One study showed abnormal placentation as a source of PE, which may result in fotal cell transfusion.
Even apart from the womb, placentation and gestation may proceed in any well-vascularized tissue within the abdominal cavity.
From the maternal aspect of care, if abnormal placentation is suspected, MRI may help assess the degree of invasion and help distinguish between placenta accreta, increta, and percreta.
The authors' report opens by saying that Caesarean section is known to be associated with an increased risk of disorders of placentation in subsequent pregnancies, but effects on the rate of antepartum stillbirth are unknown.
Fruits are 5-8 locular with axile placentation and bear one seed per locule.
Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae.
3) Other predisposing factors include previous uterine trauma, congenital anomaly, abnormal placentation, and inappropriate oxytocin administration.