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e. Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled ...
The fetuses of most mammals are situated similarly to the human fetus within their mothers. [41] However, the anatomy of the area surrounding a fetus is different in litter-bearing animals compared to humans: each fetus of a litter-bearing animal is surrounded by placental tissue and is lodged along one of two long uteri instead of the single ...
A fetus is a stage in the human development considered to begin nine weeks after fertilization. [4] [5] In biological terms, however, prenatal development is a continuum, with many defining features distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be ...
History of abortion. Indirect advertisements for abortion services, like these in The Sun in 1842, were common during the Victorian era. At the time, abortion was illegal in New York. [ 1] The practice of induced abortion —the deliberate termination of a pregnancy —has been known since ancient times. Various methods have been used to ...
Gestation. Drawing of a fetus in utero. Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). [ 1] It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for ...
Active and quiet periods for the fetus do not correspond to those of the mother; fetuses are most active from 9 a.m. to 2 p.m. and again from 7 p.m. to 4 a.m. [21] During the last four to six weeks before birth, most of the fetus's kicking and jabbing movements occur while it is sleeping lightly. [22]
Gestational age: 3 weeks and 0 days until 3 weeks and 6 days old. 22–28 days from last menstruation. Embryonic age: Week nr 2. 1 week old. 8–14 days from fertilization. Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining. They will eventually form the placenta and embryonic membranes.
Animal embryonic development. Diagram of stages of embryo development to a larval and adult stage. In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell, ( spermatozoon ...