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By the third or fourth month, erythropoiesis moves to the liver. [3] After seven months, erythropoiesis occurs in the bone marrow. Increased levels of physical activity can cause an increase in erythropoiesis. [4] However, in humans with certain diseases and in some animals, erythropoiesis also occurs outside the bone marrow, within the spleen ...
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 40 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus .
In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5]
Plant embryonic development, also plant embryogenesis, is a process that occurs after the fertilization of an ovule to produce a fully developed plant embryo. This is a pertinent stage in the plant life cycle that is followed by dormancy and germination . [ 1 ]
In some plants the gametophyte is not only small-sized but also short-lived; in other plants and many algae, the gametophyte is the "dominant" stage of the life cycle. [19] Haplodiplonts are: In archaeplastidans: red algae (which have two sporophyte generations), some green algae (e.g., Ulva), land plants [8] [9] In stramenopiles: most brown ...
Erythropoietin (/ ɪ ˌ r ɪ θ r oʊ ˈ p ɔɪ. ɪ t ɪ n,-r ə-,-p ɔɪ ˈ ɛ t ɪ n,-ˈ iː t ɪ n /; [1] [2] [3] EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bone marrow.
These hematopoietic stem cells are further closely associated with endothelial cells throughout human life. Later, they migrate to the fetal liver where the majority of physiologic EMH (extra-medullary hematopoiesis) takes place. They can also migrate to the spleen and lymph nodes where hematopoiesis can occur, but to a lesser degree.
Supravital stain of a smear of human blood from a patient with hemolytic anemia. The reticulocytes are the cells with the dark blue dots and curved linear structures (reticulum) in the cytoplasm. The normal fraction of reticulocytes in the blood depends on the clinical situation but is usually 0.5% to 2.5% in adults and 2% to 6% in infants.