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From the time of Plato through the Middle Ages, the quadrivium (plural: quadrivia [2]) was a grouping of four subjects or arts—arithmetic, geometry, music, and astronomy—that formed a second curricular stage following preparatory work in the trivium, consisting of grammar, logic, and rhetoric.
The rabbit test became a widely used bioassay (animal-based test) to test for pregnancy. The term "rabbit test" was first recorded in 1949, and was the origin of a common euphemism, "the rabbit died", for a positive pregnancy test. [4] The phrase was, in fact, based on a common misconception about the test.
Mifepristone, and also known by its developmental code name RU-486, is a drug typically used in combination with misoprostol to bring about a medical abortion during pregnancy. [8] This combination is 97% effective [ 9 ] during the first 63 days (9 weeks) of pregnancy , yet effective in the second trimester as well.
At the end of the second week of development, some cells of the trophoblast penetrate and form rounded columns into the syncytiotrophoblast. These columns are known as primary villi. At the same time, other migrating cells form into the exocoelomic cavity a new cavity named the secondary or definitive yolk sac, smaller than the primitive yolk sac.
A well-studied example of governmental restriction of birth control in order to promote higher birth rates is from 1998 Ceaușescu-era Romania. [72] [73] The surge in births resulting from Decree 770 led to great hardships for children and parents, matched by an increase in illegal abortions.
The amniotic cavity is the closed sac between the embryo and the amnion, containing the amniotic fluid. The amniotic cavity is formed by the fusion of the parts of the amniotic fold, which first makes its appearance at the cephalic extremity and subsequently at the caudal end and sides of the embryo. As the amniotic fold rises and fuses over ...
For example, Webster's Dictionary defined "pregnant" (or "pregnancy") as "having conceived" (or "the state of a female who has conceived"), in its 1828 and 1913 editions. [22] However, in the absence of an accurate understanding of human development, early notions about the timing and process of conception were often vague.
Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth. [2] The time interval of a gestation is called the gestation period. In obstetrics, gestational age refers to the time since the onset of the last menses, which on average is fertilization age plus two weeks. [3]