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Nine-week-old human embryo from an ectopic pregnancy. Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.
Drawing of the head of a four-week-old human embryo. From Gray's Anatomy. Embryo drawing is the illustration of embryos in their developmental sequence. In plants and animals, an embryo develops from a zygote, the single cell that results when an egg and sperm fuse during fertilization. In animals, the zygote divides repeatedly to form a ball ...
Human fertilization is the union of an egg and sperm, occurring primarily in the ampulla of the fallopian tube. [1] The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the 19th century. [2]
(day 20 of fertilization. [1]) Primitive heart tube is forming. Vasculature begins to develop in embryonic disc. (day 20 of fertilization. [1]) Embryo at 4 weeks after fertilization. [3] A 10mm embryo from an ectopic pregnancy, still in the oviduct. This embryo is about five weeks old (or from the seventh week of menstrual age).
The physical and functional separation of the inner cell mass from the trophectoderm (TE) is a special feature of mammalian development and is the first cell lineage specification in these embryos. Following fertilization in the oviduct, the mammalian embryo undergoes a relatively slow round of cleavages to produce an eight-cell morula. Each ...
At the 16–cell stage the compacted embryo is called a morula. [14] [15] Once the embryo has divided into 16 cells, it begins to resemble a mulberry, hence the name morula (Latin, morus: mulberry). [16] Concomitantly, they develop an inside-out polarity that provides distinct characteristics and functions to their cell-cell and cell-medium ...
Doctors say freezing embryos also gives a woman’s body time to recover before an embryo is implanted. IVF cycles involve taking medications and hormones to stimulate egg production, which takes ...
In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.. The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain extent between embryos.