amniotic fluid

Examples of amniotic fluid in the following topics:

• Amnion Development

  • The amnion contains the fluid that cushions and protects the fetus.
  • This cavity is roofed in by a single stratum of flattened, ectodermal cells called the amniotic ectoderm.
  • Outside the amniotic ectoderm is a thin layer of mesoderm (continuous with that of the somatopleure), which is connected by the body stalk with the mesodermal lining of the chorion.
  • When first formed, the amnion is in contact with the body of the embryo, but by about the fourth or fifth week, amniotic fluid (liquor amnii) begins to accumulate within it.
  • The amniotic fluid allows some free movement for the fetus during the later stages of pregnancy and also diminishes the risk of injury.

• Taste and Smell at Birth and in Old Age

  • Newborns have inherent smell and taste preferences acquired in the womb from the smell and taste of amniotic fluid, which is influenced by the mother's diet.
  • Intrauterine olfactory learning is demonstrated by behavioral evidence that newborns respond positively to the smell of their own amniotic fluid.
  • As demonstrated by animals in the wild (apes, for example), offspring are held by the mother immediately after birth without cleaning and continually exposed to the familiar odor of the amniotic fluid (making the transition from the intrauterine to extrauterine environment less overwhelming).

• Development of the Urinary System

  • Urine excreted into the amniotic cavity by the fetus forms a major component of the amniotic fluid.

• Exercise and Pregnancy

  • Contraindications for exercise include, vaginal bleeding, dyspnea before exertion, dizziness, headache, chest pain, muscle weakness, preterm labor, decreased fetal movement, amniotic fluid leakage, and calf pain or swelling (to rule out thrombophlebitis).

• Labor and Birth

  • At some point, the amniotic sac bursts and the amniotic fluid escapes.

• Oxytocin and Childbirth

  • As labor progresses, the amniotic sac can rupture, causing a slow or a fast gush of fluids.
  • Labor usually begins within a 24 hour period after the amniotic sac has ruptured.
  • The amniotic fluid is drained, and the baby is delivered.
  • The baby's mouth and nose are cleared of fluids, and the umbilical cord is clamped and cut.

• Onset of Labor

  • As labor progresses the amniotic sac can rupture and cause a slow or a fast gush of fluids.
  • Labor usually begins within a 24-hour period after the amniotic sac ruptures.

• Characteristics of Amniotes

  • The distinguishing characteristic of amniotes, a shelled egg with an amniotic membrane, allowed them to venture onto land.
  • The amniotes, reptiles, birds, and mammals, are distinguished from amphibians by their terrestrially-adapted egg, which is protected by amniotic membranes.
  • The evolution of amniotic membranes meant that the embryos of amniotes were now provided with their own aquatic environment, which led to less dependence on water for development, allowing the amniotes to branch out into drier environments.
  • The amniotic egg is the key characteristic of amniotes .
  • The key features of an amniotic egg are the chorion, amnion, and allantois.

• Evolution of Amniotes

  • Modern amniotes, which includes mammals, reptiles, and birds, evolved from an amphibian ancestor approximately 340 million years ago.
  • The first amniotes evolved from their amphibian ancestors approximately 340 million years ago during the Carboniferous period.
  • The early amniotes diverged into two main lines soon after the first amniotes arose.
  • In the past, the most common division of amniotes has been into the classes Mammalia, Reptilia, and Aves.
  • This chart shows the evolution of amniotes.

• Blastocyst Formation

  • The trophoblast surrounds the inner cell mass and a fluid-filled, blastocyst cavity known as the blastocoele or the blastocystic cavity.
  • Spaces appear between the remaining cells of the mass and, by the enlargement and coalescence of these spaces, a cavity called the amniotic cavity is gradually developed.