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[12] [13] Subsequently, new cells derived from yolk sac will be established between trophoblast and exocoelomic membrane and will give rise to extra-embryonic mesoderm, which will form the chorionic cavity. [11] At the end of the second week of development, some cells of the trophoblast penetrate and form rounded columns into the ...
It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell . [2]
Mitotic cell division enables sexually reproducing organisms to develop from the one-celled zygote, which itself is produced by fusion of two gametes, each having been produced by meiotic cell division. [5] [6] After growth from the zygote to the adult, cell division by mitosis allows for continual construction and repair of the organism. [7]
[1] [2] [3] These two layers of cells are stretched between two fluid-filled cavities at either end: the primitive yolk sac and the amniotic sac. The epiblast is adjacent to the trophoblast and made of columnar epithelial cells ; the hypoblast is closest to the blastocoel (blastocystic cavity) and made of cuboidal cells.
A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. [1] [2] In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: Blood pressure. Aortic ...
Overall, the systolic and diastolic blood pressure drops 10–15 mm Hg in the first trimester and then returns to baseline in the second half of pregnancy. [6] All of these cardiovascular adaptations can lead to common complaints, such as palpitations, decreased exercise tolerance, and dizziness.
In the fetal stage, the lungs fill with fluid and collapse because the fetus is within the amniotic sac and the placenta is providing the oxygen it needs to grow. With the lung collapsed, pulmonary vascular resistance remains high during the fetal stage to prevent blood flow into the lungs. [2]
This is an accepted version of this page This is the latest accepted revision, reviewed on 5 January 2025. Cell division producing haploid gametes For the figure of speech, see Meiosis (figure of speech). For the process whereby cell nuclei divide to produce two copies of themselves, see Mitosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...