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Whereas the beta form had been identified in 1845, [3] α-PbO 2 was first identified in 1946 and found as a naturally occurring mineral 1988. [4] The alpha form has orthorhombic symmetry, space group Pbcn (No. 60), Pearson symbol oP12, lattice constants a = 0.497 nm, b = 0.596 nm, c = 0.544 nm, Z = 4 (four formula units per unit cell). [4]
Scrutinyite / ˈ s k r uː t ɪ n i. aɪ t / is a rare oxide mineral and is the alpha crystalline form of lead dioxide (α-PbO 2), plattnerite being the other, beta form. The mineral was first reported in 1988 and its name reflects the scrutiny and efforts required to identify it from a very limited amount of available sample material.
The SA node cells are smaller and paler than the surrounding atrial cells, with the average cell being around 8 micrometers in diameter and 20-30 micrometers in length (1 micrometer= 0.000001 meter). [7] Unlike the atrial cells, SA node cells contain fewer mitochondria and myofibers, as well as a smaller sarcoplasmic reticulum.
The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division.
The T cell-dependent processes are subdivided into primary and secondary responses: a primary response (meaning that the T cell is present at the time of initial contact by the B cell with the antigen) produces short-lived cells that remain in the extramedullary regions of lymph nodes; a secondary response produces longer-lived cells that ...
Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.
In anatomy the term reticuloendothelial system (abbreviated RES), often associated nowadays with the mononuclear phagocyte system (MPS), was employed by the beginning of the 20th century to denote a system of specialised cells that effectively clear colloidal vital stains (so called because they stain living cells) from the blood circulation.
Merocrine secretion Paneth cells, located at the base of the crypts of the small intestinal mucosa, and displaying merocrine secretion of bright red cytoplasmic granules. H&E stain. Merocrine (or eccrine) is a term used to classify exocrine glands and their secretions in the study of histology.