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Multicellular eukaryotes are made of two fundamental cell types: germ and somatic cells. Germ cells produce gametes and are the only cells that can undergo meiosis as well as mitosis. Somatic cells are all the other cells that form the building blocks of the body and they only divide by mitosis. The lineage of germ cells is called the germline.
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 mutation frequencies for cells in different stages of gametogenesis are about 5 to 10-fold lower than in somatic cells both for spermatogenesis [18] and oogenesis. [19] The lower frequencies of mutation in germline cells compared to somatic cells appears to be due to more efficient DNA repair of DNA damages, particularly homologous ...
The inner cell mass initially has two layers: the hypoblast and epiblast. At the end of the second week, a primitive streak appears. The epiblast in this region moves towards the primitive streak, dives down into it, and forms a new layer, called the endoderm , pushing the hypoblast out of the way (this goes on to form the amnion .)
This occurs only in select organisms, however some without a Weismann barrier do present germ-soma differentiation. These organisms include land plants, many algaes, invertebrates, and fungi whose germ cells are derived from prior somatic cells as opposed to stem cells. The Weismann barrier is essential to the concept of an immortal germline ...
The cell wall acts to protect the cell mechanically and chemically from its environment, and is an additional layer of protection to the cell membrane. Different types of cell have cell walls made up of different materials; plant cell walls are primarily made up of cellulose, fungi cell walls are made up of chitin and bacteria cell walls are ...
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Among the many lines of evidence supporting symbiogenesis are that mitochondria and plastids contain their own chromosomes and reproduce by splitting in two, parallel but separate from the sexual reproduction of the rest of the cell; that the chromosomes of some mitochondria and plastids are single circular DNA molecules similar to the circular ...