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Parietal epithelial cell (PEC) Podocyte; Angioblast → Endothelial cell; Mesangial cell. Intraglomerular; Extraglomerular; Juxtaglomerular cell; Macula densa cell; Stromal cell → Interstitial cell → Telocytes; Kidney proximal tubule brush border cell; Kidney distal tubule cell; Connecting tubule cells; α-intercalated cell; β-intercalated ...
The somatic cells on the path of germ cells provide them attractive, repulsive, and survival signals. But germ cells also send signals to each other. [citation needed] In reptiles and birds, germ cells use another path. PGCs come from the epiblast and move to the hypoblast to form the germinal crescent (anterior extraembryonic
The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of the whole of the digestive tract except part of the mouth and pharynx and the terminal part of the rectum (which are lined by involutions of the ectoderm). It also forms the lining cells of all the glands which open into the ...
Other types of epithelium are derived from the endoderm. [3] In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. [4]
Mesoderm cells condense to form a rod which will send out signals to redirect the ectoderm cells above. This fold along the neural tube sets up the vertebrate central nervous system. The endoderm is the inner most germ layer of the embryo which gives rise to gastrointestinal and respiratory organs by forming epithelial linings and organs such ...
The actual skin colour of different humans is affected by many substances, although the single most important substance determining human skin colour is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin colour of darker-skinned humans.
Histogenesis is the formation of different tissues from undifferentiated cells. [1] These cells are constituents of three primary germ layers , the endoderm , mesoderm , and ectoderm . The science of the microscopic structures of the tissues formed within histogenesis is termed histology .
In normal skin, the rate of keratinocyte production equals the rate of loss, [4] taking about two weeks for a cell to journey from the stratum basale to the top of the stratum granulosum, and an additional four weeks to cross the stratum corneum. [2] The entire epidermis is replaced by new cell growth over a period of about 48 days. [13]