BlastocystThe blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the embryoblast which subsequently forms the embryo, and an outer layer of trophoblast cells called the trophectoderm. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoel. In the late blastocyst the trophectoderm is known as the trophoblast. The trophoblast gives rise to the chorion and amnion, the two fetal membranes that surround the embryo.
AnovulationAnovulation is when the ovaries do not release an oocyte during a menstrual cycle. Therefore, ovulation does not take place. However, a woman who does not ovulate at each menstrual cycle is not necessarily going through menopause. Chronic anovulation is a common cause of infertility. In addition to the alteration of menstrual periods and infertility, chronic anovulation can cause or exacerbate other long-term problems, such as hyperandrogenism or osteopenia. It plays a central role in the multiple imbalances and dysfunctions of polycystic ovary syndrome.
SurrogacySurrogacy is an arrangement, often supported by a legal agreement, whereby a woman agrees to delivery/labour on behalf of another couple or person, who will become the child's parent(s) after birth. People may seek a surrogacy arrangement when a couple do not wish to carry a pregnancy themselves, when pregnancy is medically impossible, when pregnancy risks are dangerous for the intended mother, or when a single man or a same sex couple wish to have a child. In surrogacy arrangements, monetary compensation may or may not be involved.
Multiple birthA multiple birth is the culmination of one multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such births are often named according to the number of offspring, as in twins and triplets. In non-humans, the whole group may also be referred to as a litter, and multiple births may be more common than single births. Multiple births in humans are the exception and can be exceptionally rare in the largest mammals.
Implantation (embryology)Implantation, also known as nidation is the stage in the embryonic development of mammals in which the blastocyst hatches, attaches, adheres, and invades into the wall of the female's uterus. Implantation is the first stage of gestation, and, when successful, the female is considered to be pregnant. An implanted embryo is detected by the presence of increased levels of human chorionic gonadotropin (hCG) in a pregnancy test. The implanted embryo will receive oxygen and nutrients in order to grow.
Ectopic pregnancyEctopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. The pain may be described as sharp, dull, or crampy. Pain may also spread to the shoulder if bleeding into the abdomen has occurred. Severe bleeding may result in a fast heart rate, fainting, or shock. With very rare exceptions, the fetus is unable to survive.
Intrauterine growth restrictionIntrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's birth weight percentile. The causes of IUGR are broad and may involve maternal, fetal, or placental complications. At least 60% of the 4 million neonatal deaths that occur worldwide every year are associated with low birth weight (LBW), caused by intrauterine growth restriction (IUGR), preterm delivery, and genetic abnormalities, demonstrating that under-nutrition is already a leading health problem at birth.
Mitochondrial diseaseMitochondrial disease is a group of disorders caused by mitochondrial dysfunction. Mitochondria are the organelles that generate energy for the cell and are found in every cell of the human body except red blood cells. They convert the energy of food molecules into the ATP that powers most cell functions. Mitochondrial diseases take on unique characteristics both because of the way the diseases are often inherited and because mitochondria are so critical to cell function.
CryopreservationCryopreservation or cryoconservation is a process where biological material - cells, tissues, or organs - are frozen to preserve the material for an extended period of time. At low temperatures (typically or using liquid nitrogen) any cell metabolism which might cause damage to the biological material in question is effectively stopped. Cryopreservation is an effective way to transport biological samples over long distances, store samples for prolonged periods of time, and create a bank of samples for users.
Egg donationEgg donation is the process by which a woman donates eggs to enable another woman to conceive as part of an assisted reproduction treatment or for biomedical research. For assisted reproduction purposes, egg donation typically involves in vitro fertilization technology, with the eggs being fertilized in the laboratory; more rarely, unfertilized eggs may be frozen and stored for later use. Egg donation is a third-party reproduction as part of assisted reproductive technology.
