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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.
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization, and continues as fetal development. By the end of the tenth week of gestational age, the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where ...
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 ...
In human prenatal development, fetal development begins from the ninth week after fertilization (or eleventh week gestational age) and continues until the birth of a newborn. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus.
Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosis and cell differentiation, and the resulting embryo then implants in the uterus, where the embryo ...
The fetal circulatory system includes three shunts to divert blood from undeveloped and partially functioning organs, as well as blood supply to and from the placenta. In humans, the circulatory system is different before and after birth. The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical ...
Heart development. Development of the human heart during the first five weeks (top), and the formation of the heart chambers (bottom) at four and eight weeks. In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a ...
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 ...