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Encyclopedia > Amniotic sac
A drawing of the amniotic sac from Gray's Anatomy.
A drawing of the amniotic sac from Gray's Anatomy.

The amniotic sac is a tough but thin transparent pair of membranes, which hold a developing embryo (and later fetus) until shortly before birth. The inner membrane, the amnion, contains the amniotic fluid and the fetus. The outer membrane, the chorion, contains the amnion and is part of the placenta. It is also called the amniotic bubble because of its resemblance to a bubble. When in the light, the amniotic sac is shiny and very smooth, but too tough to pierce through. Image File history File links Gray34. ... Image File history File links Gray34. ... An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy after Henry Gray, is an anatomy textbook widely regarded as a classic work on human anatomy. ... It has been suggested that embryology be merged into this article or section. ... A human fetus A fetus (or foetus, or fœtus – see below) is a developing mammal after the embryonic stage and before birth. ... Childbirth (also called labour, birth, partus or parturition) is the culmination of a human pregnancy with the emergence of a newborn infant from its mothers uterus. ... For the alien race in Stephen Donaldsons The Gap Cycle, see Amnion (Gap Cycle). ... For the entertainment company see Chorion (company) The chorion surrounds the embryo and other membranes. ... The placenta is an ephemeral (temporary) organ present only in female placental vertebrates during gestation (pregnancy). ...


An artificial rupture of membranes (ARM), also known as an amniotomy, may be performed by a midwife or obstetrician. This is usually performed using an amnihook and is intended to induce or accelerate labour. Midwifery is a blanket term used to describe a number of different types of health practitioners, other than doctors, who provide prenatal care to expecting mothers, attend the birth of the infant and provide postnatal care to the mother and infant. ... This does not cite its references or sources. ...


Amniotic fluid

Amniotic fluid is the watery liquid surrounding and cushioning a growing fetus within the amnion. It allows the fetus to move freely without the walls of the uterus being too tight against its body. Buoyancy is also provided. The uterus or womb is the major female reproductive organ of most mammals, including humans. ...


The amnion grows and begins to fill, mainly with water, around two weeks after fertilisation. After a further 10 weeks the liquid contains proteins, carbohydrates, lipids and phospholipids, urea and electrolytes, all which aid in the growth of the fetus. Most of the amniotic fluid comes from the fetus's urine. By the second trimester the fetus can breathe in the water, allowing normal growth and the development of lungs and the gastrointestinal tract. A spermatozoon fertilising an ovum Fertilisation or fertilization (also known as conception, fecundation and syngamy), is fusion of gametes to form a new organism of the same species. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Lactose is a disaccharide found in milk. ... Lipids are a class of hydrocarbon-containing organic compounds. ... Two schematic representations of a phospholipid. ... Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen, with the formula CON2H4 or (NH2)2CO. Urea is also known as carbamide, especially in the recommended International Non-proprietary Names (rINN) in use in Europe. ... An electrolyte is a substance containing free ions which behaves as an electrically conductive medium. ... This article or section is in need of attention from an expert on the subject. ... The human gestation period of approximately 40 weeks between the time of the last menstrual cycle and delivery is traditionally divided into three periods of three months, or trimesters. ... Respiratory system The lungs flank the heart and great vessels in the chest cavity. ... The gastrointestinal tract (GI tract), also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ...


Recent research by researchers led by Anthony Atala of Wake Forest University and a team from Harvard University has found that amniotic fluid is also a plentiful source of non-embryonic stem cells.[1] These cells have demonstrated the ability to differentiate into a number of different cell-types, including brain, liver and bone. Anthony Atala, M.D., is the Director of the Wake Forest Institute for Regenerative Medicine, and Chair of the Department of Urology at the Wake Forest University School of Medicine in the state of North Carolina in the United States. ... Wake Forest University is a private, coeducational university located in Winston-Salem, North Carolina. ... Harvard redirects here. ... Mouse embryonic stem cells. ...


The forewaters are released when the amnion ruptures, commonly known as when a woman's "waters break" or "spontaneous rupture of membranes" (SROM). The majority of the hindwaters remain inside the womb until the baby is born.


Complications related to amniotic fluid

Amnion.jpg (view file)

The amniotic sac opened during surgery. Image File history File linksMetadata Download high resolution version (1415x1303, 1191 KB) Description: en:amnionic sac de:Fruchtblase, Nachgeburt Date: 2005-07-29 Fotographer: user:special License: File links The following pages link to this file: Amniotic sac Metadata This file contains additional information, probably added from the digital camera...

Too little amniotic fluid (oligohydramnios) or too much (polyhydramnios or hydramnios) can be a cause or an indicator of problems for the mother and baby. In both cases the majority of pregnancies proceed normally and the baby is born healthy but this isn't always the case. Babies with too little amniotic fluid can develop contractures of the limbs, clubbing of the feet and hands, and also develop a life threatening condition called hypoplastic lungs. If a baby is born with hypoplastic lungs, which are small underdeveloped lungs, this condition is potentially fatal and the baby can die shortly after birth. The amniotic sac is a tough but thin transparent pair of membranes which holds a developing embryo (and later fetus) until shortly before birth. ... The amniotic sac is a tough but thin transparent pair of membranes which holds a developing embryo (and later fetus) until shortly before birth. ...


On every prenatal visit, the obstetrician/gynaecologist should measure the patient's fundal height with a tape measure. It is important that the fundal height be measured and properly recorded to insure proper fetal growth and the increasing development of amniotic fluid. The obstetrician/gynaecologist should also routinely ultrasound the patient – this procedure will also give an indication of proper fetal growth and amniotic fluid development. Oligohydramnios can be caused by infection, procedures such as chorionic villus sampling (CVS), and preterm premature rupture of membranes (PPROM). Fundal height, or MacDonalds rule, is a measure of the size of the uterus used to assess fetal growth and development. ... Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structure and any pathological lesions, making them useful for scanning the organs. ... Chorionic villus sampling (CVS) is a form of prenatal diagnosis to determine genetic abnormalities in the fetus. ...


Oligohydramnios can be treated with bed rest, oral and intravenous hydration, antibiotics, steroids, and amnioinfusion. Rehydration is the pissing of water and electrolytes lost through dehydration. ... Staphylococcus aureus - Antibiotics test plate. ... Steroid skeleton of lanosterol. ...


Polyhydramnios is a predisposing risk factor for cord prolapse and is sometimes a side effect of a macrosomic pregnancy. Hydramnios is associated with esophageal atresia. Amniotic fluid is primarily produced by the mother until 16 weeks of gestation. Cord prolapse is an obstetric emergency during pregnancy or labour. ... Macrosomia, sometimes also called big baby syndrome, is a potential complication during childbirth and the latter stages of pregnancy. ... Esophageal atresia is a congenital medical condition (birth defect) which effects the alimentary tract. ...


Preterm premature rupture of membranes (PPROM) is a condition where the amniotic sac leaks fluid before 38 weeks of gestation. This can be caused by a bacterial infection or by a defect in the structure of the amniotic sac, uterus, or cervix. In some cases, the leak can spontaneously heal, but in most cases of PPROM, labor begins within 48 hours of membrane rupture. When this occurs, it is necessary that the mother receive treatment to avoid possible infection in the newborn.


A rare and often fatal obstetric complication is an amniotic fluid embolism, which causes disseminated intravascular coagulation. This does not cite its references or sources. ... In medicine, an embolism occurs when an object (the embolus, plural emboli) migrates from one part of the body (through circulation) and cause(s) a blockage (occlusion) of a blood vessel in another part of the body. ... Disseminated intravascular coagulation (DIC) is a pathological process in the body where the blood starts to coagulate throughout the whole body. ...


Multiple pregnancies

Twins and multiple pregnancies sometimes share the amnion and the chorion. Monoamniotic pregnancy is when each embryo or foetus from one single zygote (monozygotic, commonly known as identical twins) is located within the same amnion which is itself in one chorion (monochorionic). Diamniotic pregnancy is when there are more than one amnions inside one chorion or each having their own chorion (dichorionic). Dizygotic (fraternal, non-identical) twins each have their own amnion and chorion and may or may not share a placenta. For multiple births that involve more than two fetuses, see multiple birth. ... Identical triplet brothers Quadruplet, quintuplet, etc. ... A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization. ...


Sharing the same amnion (or the same amnion and placenta) can cause complications in pregnancy. For example, the umbilical cords of monoamniotic twins can become entangled, reducing or interrupting the blood supply to the developing fetus. Monochorionic twins, sharing one placenta, usually also share the placental blood supply. In rare cases, blood passes disproportionately from one twin to the other through connecting blood vessels within their shared placenta, leading to twin-to-twin transfusion syndrome. Twin-to-twin transfusion syndrome (TTTS, also known as Feto-Fetal Transfusion Syndrome (FFTS) and Twin Oligohydramnios-Polyhydramnios Sequence (TOPS)) is a disorder that can affect identical twin or higher multiple pregnancies where two or more fetuses share a common (monochorionic) placenta. ...


 
 

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