Placentation In biology, placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove waste from the embryo.
What is placentation class 11th biology?
Placentation is defined as the arrangement of the placenta in the ovary of a flower. The placenta connects the ovules with the wall of the ovary.
What is placentation Class 11 Ncert?
Placentation: It is defined as the arrangement of ovules within the ovary. several different forms of placentation can be seen in flowering plants.
What are types of placentation?
There are five types of placentation that occurs in flowering plants i.e. axile, marginal, parietal, basal, superficial placentation.
What is placentation in biology class 12?
The arrangement of placenta and ovules within the ovary is called placentation. There are different kinds of placentation namely, marginal, parietal, axile, free central, basal and superficial placentation. In marginal placentation, placenta bearing ovules develop along the junction of the two margins of the carpel.
What is placentation Class 11 Shaalaa?
The term 'placentation' refers to the arrangement of ovules within the ovary of a flower. It is primarily of five types, namely marginal, basal, parietal, axile, and free central.
What is placentation describe its types with diagram?
Placentation refers to the arrangement of ovules inside the ovary. It is of five basic types. When the ovules develop on the inner walls of the ovary, the ovary is said to have parietal placentation. In axile placentation, the placenta is axial and ovules are attached to it.
What are the four types of placenta?
Posterior placenta: The placenta grows on the back wall of your uterus. Anterior placenta: The placenta grows on the front wall of your uterus closest to your abdomen. Fundal placenta: The placenta grows at the top of your uterus. Lateral placenta: The placenta grows on the right or left wall of your uterus.
What is the function of placenta in plants?
Funiculus in the part equivalent to the umbilical cord in which the ovules are attached inside a flower's ovary. The part of the ovary where funiculus is present is called the placenta. Its function is to provide a connection with the ovary walls and the flower and provide nutrients to the developing embryo.
What type of placentation is banana?
Ovary inferior, tricarpellary, syncarpous, trilocular, numerous ovules on axile placentation. The style is simple and filiform.
What is placentation in a fruit name five types of placentation and give examples in each?
The arrangement of seeds in fruits depends on placentation. The different types of Placentation found in angiosperms are marginal, axile, parietal, free central, basal, and superficial; for example, pea shows marginal placentation, whereas tomato shows axile placentation.
Where is placenta located in plants?
placenta, plural Placentas, orPlacentae, in botany, the surface of the carpel (highly modified leaf) to which the ovules (potential seeds) are attached. The placenta is usually located in a region corresponding somewhat to the margins of a leaf but is actually submarginal in position.
What is the placentation of tomato?
Axile typeComplete answer: Axile type of placentation is seen in lemon and tomato. In this type of placentation, the ovary is partitioned into two or more chambers by septa.
What is free Central placentation Class 11?
A single chambered ovary with ovules borne on the central axis has free central placentation.
What is placentation Class 9?
It is defined as the arrangement and attachment of ovules within the plant's ovary. The ovules get attached via funicle, and the part of the ovary where ovules are attached is the placenta.
What is placenta describe placentation and also write a function of placenta?
The placenta is an organ that develops in the uterus during pregnancy. This structure provides oxygen and nutrients to a growing baby. It also removes waste products from the baby's blood. The placenta attaches to the wall of the uterus, and the baby's umbilical cord arises from it.
What is the placentation of mango?
Placentation when unilocular parietal, or basal. Ovules in the single cavity 1; pendulous, or ascending; apotropous; with ventral raphe, or with dorsal raphe; non-arillate; anatropous.
What is placentation?
The mode of arrangement of ovules within the ovary is called placentation. The placenta is a tissue that develops along the inner wall of the ovary...
What is the significance of placentation?
Placentation provides nourishment to the developing ovule and protects them too.
What is free central placentation?
Free central placentation is a type in which the gynoecium is polycarpellary, and ovules borne at the center of the ovary, which is quite separate...
Which family has axile placentation?
The axile placentation is found in the families of Solanaceae and Liliaceae.
How many types of Placentation are there?
The main types of placentation are marginal, parietal, axile, free-central, basal, and superficial.
Is Lemon axile placentation?
Yes, lemon is axile placentation.
What is monocarpellary?
When only one carpel is present in the gynoecium of a flower, it is known as monocarpellary.
With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
The eight nucleate female gametophytes of flowering plants have an egg apparatus made of one egg cell and two flanking cells at the micropylar end....
Describe the development of female gametophyte in Angiosperms.
The angiosperm female gametophyte is critical for plant reproduction. Female gametophyte development begins early in ovule development with the for...
Match the following and choose the correct combination from the options given below.Column I(Placent...
Basal: The ovary is unilocular and a single ovule is borne at the base of ovary. For example, Marigold, Sunflower (Asteraceae family). Free central...
Perisperm is
Correct option: DExplanation:Perisperm is the nutritive tissue surrounding the embryo in certain seeds and developing from the nucellus of the ovul...
Describe the various types of placentations found in flowering plants.
Placentation refers to the arrangement of ovules inside the ovary. It is of five basic types:(A) Marginal placentation-The ovary in which the place...
What is meant by the monosporic development of female gametophyte? Explain the development of female...
The formation of the female gametophyte from a single functional megaspore is called as monosporic development.The nucleus of functional megaspore...
Free-central placentation is found in
Free central placentation is present in single chambered ovary with ovules borne on the central axis. Brassica and Argemone (parietal placentation)...
Filiform apparatus is a characteristic feature of :
A. Correct option:-DB. Explanation for the option:Filiform apparatus is a prolongation of the synergids beyond the summit of the embryo sac. The fu...
With the help of a neat and labelled diagram describe the development of female gametophyte of angio...
Female Gametophyte i.e. embryo sac develops from megaspore mother cell (MMC) inside the ovule through the processes megasporogenesis and megagameto...
The characteristic of anatropous ovule is?
Anatropous ovule is the most common type of ovules, which occurs in more than 80% of angiospermic families. The body of ovule is rotated by 180° an...
What is the placentation of a plant?
Placentation is the arrangement of ovules in the ovary of a plant. The given diagram shows the types of placentation such as basal, apical, parietal, marginal, axial, and free central.
Where do ovules develop?
3. Parietal: Ovules develop on the inner wall of the ovary e.g., Poppy.
What is the process of placentation?
It progresses through stages of apposition, adhesion and attachment, culminating in the development of a physical union between the embryonic membrane and the uterine lining. Once the elongated vesicle assumes a fixed position within the uterus (apposition), the chorion and uterine epithelium develop an adhesive surface coating that maintains a very intimate contact. The apposed maternal and embryonic cells then develop very tiny finger-like processes on their surfaces (microvilli) which interdigitate to consolidate attachment. This union between the conceptus and maternal tissues results in a unique but temporary organ, the placenta.
What is placentation in animals?
Placentation is a phenomenon that is found in many animals, including insects and velvet worms, but is mostly studied in vertebrates. This brief overview covers the different types of placentation and their evolution in mammals.
What is the function of placenta?
Placentation, the first test of the embryo's differentiative and organogenetic capacity, accomplishes two critical events: attaching the conceptus to the uterus and bringing the fetal and maternal circulations into close proximity to facilitate effective gas, nutrient, and waste exchange. These functions require that fetal placental cells (trophoblasts) acquire an invasive phenotype. In mammals that form a hemochorial placenta (e.g., humans and mice), fetal trophoblasts come in direct contact with maternal blood. Thus, placentation also entails the unique requirement for close cooperation and direct cellular contact between two immunologically distinct organisms.
How does ovine placentation occur?
This is followed almost immediately by adhesion and attachment between the chorionic membrane near the embryonic disc and the associated uterine epithelium. The process subsequently spreads, resulting in intimate attachment between most of the chorion and the apposed uterine surface during the 4th week of gestation. As in the cow and goat, initial attachment occurs in both the caruncular and intercaruncular regions. A few binucleate cells appear in the ovine chorion by day 16 and their migration across the interface commences at this time. Migrant binucleate cells fuse with other binucleate or uterine epithelial cells creating multinucleate cells that subsequently spread or flatten to produce an extensive syncytium on the maternal side of the interface. The formation of multinucleate cells and syncytium is accompanied by degeneration of maternal epithelial cells so that much of the ovine uterine epithelium is replaced by migrant chorionic tissue.
What is the placentome made of?
Each placentome is subdivided into trophoblast-rich cotyledon tissue and an adjacent caruncle composed of uterine tissue. This type of placentation exhibits a maximal number of maternal and extraembryonic cell layers constituting the placental barrier and an unusual differentiated cell type, the binucleate cell (Wooding, 1992).
How do cows form placentomes?
The interface between the chorion and maternal tissue in cows is undulating by day 30 and the attachment process is reinforced in the placentomes through penetration of chorionic villi into maternal crypts commencing around day 33. Lengthening and secondary branching of the villi and deepening of the crypts result in formation of mature placentomes. Placentome formation, like all aspects of placentation, begins in the proximity of the embryonic disc so the most advanced structures are found here with smaller, less-developed formations near the tips of the uterine horns. The placentomes in the middle and body region of the ipsilateral horn are larger than those in other portions of the uterus.
Why is ruminant placentation described as syndesmochorial?
Ruminant placentation is described as syndesmochorial because of the transient erosion and regrowth of the maternal epithelium , which results in the intermittent exposure of maternal endothelium (capillaries) to chorionic epithelium (Senger, 2003 ).
What is the function of placentation?
The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove waste from the embryo. Placentation is best known in live-bearing mammals ( ...
What is the placentation of a plant?
In flowering plants, placentation is the attachment of ovules inside the ovary. The ovules inside a flower 's ovary (which later become the seeds inside a fruit) are attached via funiculi, the plant part equivalent to an umbilical cord. The part of the ovary where the funiculus attaches is referred to as the placenta .
How many times have the placenta evolved?
In vertebrates, placentas have evolved more than 100 times independently, with the majority of these instances occurring in squamate reptiles. The placenta can be defined as an organ formed by the sustained apposition or fusion of fetal membranes and parental tissue for physiological exchange.
Which reptiles have epitheliochorial placentation?
Most reptiles exhibit strict epitheliochorial placentation (e.g. Pseudemoia entrecasteauxii) however at least two examples of endotheliochorial placentation have been identified ( Mabuya sp. and Trachylepis ivensi ). Unlike eutherian mammals, epitheliochorial placentation is not maintained by maternal tissue as embryos do not readily invade tissues outside of the uterus.
What is the placenta?
The part of the ovary where the funiculus attaches is referred to as the placenta . In botany, the term placentation most commonly refers to the arrangement of ovules inside an ovary. Placentation types include: Basal: The placenta is found in mono to multi carpellary, syncarpous ovary.
What is the risk of a monochorionic placenta?
Monochorionic placentation occurs when monozygotic twins develop with only one placenta and bears a higher risk of complications during pregnancy. Abnormal placentation can lead to an early termination of pregnancy, for example in pre-eclampsia .
How long does it take for a human to develop a placenta?
In humans, placentation takes place 7–8 days after fertilization. In humans, the placenta develops in the following manner.
How is the placenta delivered?
If you deliver your baby vaginally, you'll also deliver the placenta vaginally — during what's known as the third stage of labor.
Where is the placenta located during pregnancy?
The placenta is a structure that develops in the uterus during pregnancy. In most pregnancies, the placenta is located at the top or side of the uterus. In placenta previa, the placenta is located low in the uterus.
What affects placental health?
Various factors can affect the health of the placenta during pregnancy, with some under your control and some not. For example:
What are the most common placental problems?
The placenta is an organ that develops in the uterus during pregnancy. Placental abruption occurs when the placenta separates from the inner wall of the uterus before birth. Placental abruption can deprive the baby of oxygen and nutrients and cause heavy bleeding in the mother. In some cases, early delivery is needed.
What happens if your placenta is removed before delivery?
After delivery, retained placenta is sometimes a concern. Here's what you need to know about these conditions: Placental abruption. If the placenta peels away from the inner wall of the uterus before delivery — either partially or completely — a condition known as placental abruption develops.
Why is my placenta still attached to my uterus?
A retained placenta might occur because the placenta becomes trapped behind a partially closed cervix or because the placenta is still attached to the uterine wall. Left untreated, a retained placenta can cause severe infection or life-threatening blood loss.
What causes the placenta to separate from the uterus?
Abdominal trauma. Trauma to your abdomen — such as from a fall, auto accident or other type of blow — increases the risk of the placenta prematurely separating from the uterus (placenta abruption).
What are the different types of placentation?
The following points highlight the top six types of placentation in a plant. The types are: 1. Marginal 2. Parietal 3. Axile 4. Free-central 5. Superficial or Laminar 6. Basal.
How is the placenta formed?
The placenta is formed by the swelling up of cohering margins, and on the latter develop the ovules in rows. It occurs in bicarpellary or multicarpellary but unilocular ovary, e.g., Papaveraceae. Placentation in Plants: Type # 3. Axile: ADVERTISEMENTS:
Where do ovules develop?
Here, the ovules develop over the entire inner surface of the carpels. It occurs in multicarpellary ovary, e.g., Nymphaea. Placentation in Plants: Type # 6. Basal: The placenta develops directly on the thalamus and bears a single ovule at the base of the unilocular ovary, e.g., Compositae.
Where do ovules form?
The ovules develop in rows near the margin on the placenta formed along the ventral suture. It occurs in monocarpellary and unilocular ovary, e.g., Leguminosae. Placentation in Plants: Type # 2. Parietal: The placenta is formed by the swelling up of cohering margins, and on the latter develop the ovules in rows.
Overview
Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove waste from the embryo. Placentation is best known in live-bearing mammals (theria), but also occurs in some fish, reptiles, amphibians, a diversit…
In mammals
In live bearing mammals, the placenta forms after the embryo implants into the wall of the uterus. The developing fetus is connected to the placenta via an umbilical cord. Mammalian placentas can be classified based on the number of tissues separating the maternal from the fetal blood. These include:
endotheliochorial placentation In this type of placentation, the chorionic villi are in contact with t…
In lizards and snakes
As placentation often results during the evolution of live birth, the more than 100 origins of live birth in lizards and snakes (Squamata) have seen close to an equal number of independent origins of placentation. This means that the occurrence of placentation in squamata is more frequent than in all other vertebrates combined, making them ideal for research on the evolution of placentation and viviparity itself. In most squamates two separate placentae form, utilising separate embryon…
Research
The placenta is an organ that has evolved multiple times independently, evolved relatively recently in some lineages, and exists in intermediate forms in living species; for these reasons it is an outstanding model to study the evolution of complex organs in animals. Research into the genetic mechanisms that underpin the evolution of the placenta have been conducted in a diversity of animals including reptiles, seahorses, and mammals.
In plants
In flowering plants, placentation is the attachment of ovules inside the ovary. The ovules inside a flower's ovary (which later become the seeds inside a fruit) are attached via funiculi, the plant part equivalent to an umbilical cord. The part of the ovary where the funiculus attaches is referred to as the placenta.
In botany, the term placentation most commonly refers to the arrangement of …
See also
• Choriovitelline placenta
• Gynoecium
External links
• Fachbereich Biologie (Department of Biology) → teaching stuff → B-Online → Homepage: Botany Online - The Internet Hypertextbook → Contents → How to Identify Plants → Flowers
Causes
Overview
- The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it. The organ is usually attached to the top, side, front or back of...
Clinical significance
- Various factors can affect the health of the placenta during pregnancy, some modifiable and some not. For example:
Risks
- During pregnancy, possible placental problems include placental abruption, placenta previa and placenta accreta. These conditions can cause potentially heavy vaginal bleeding. After delivery, retained placenta is also sometimes a concern. Here's what you need to know about these conditions:
Prevention
- Most placental problems can't be directly prevented. However, you can take steps to promote a healthy pregnancy. For example: If you've had a placental problem during a previous pregnancy and are planning another pregnancy, talk to your health care provider about ways to reduce the risk of experiencing the condition again. Tell your health care provider if you've had surgery on y…
Treatment
- If you deliver your baby vaginally, you'll also deliver the placenta vaginally during what's known as the third stage of labor. After you give birth, you'll continue to have mild contractions. Your health care provider might give you a medication called oxytocin (Pitocin) to reduce postpartum bleeding. Your health care provider might also massage your lower abdomen to encourage your …