| 释义 |
microsome Biol.|ˈmaɪkrəsəʊm|
Also quasi-L. microˈsoma, pl. -ˈsomata.
[mod.L. mīcrosōma, f. Gr. µῑκρό-ς small + σῶµα body.]
a. A name given by Hanstein (1880) to certain small granules which abound in vegetating cells of protoplasm.
1885G. L. Goodale Physiol. Bot. 211 Imbedded in the protoplasm,..there are generally minute granules which have a high degree of refringency..; these are the microsomata of Hanstein. 1887Ward tr. Sachs' Physiol. Plants 79 This..is thickly set with very numerous small granules (microsomes). 1900A. J. Ewart tr. Pfeffer's Physiol. Plants (ed. 2) I. ii. 43 Cytoplasm may contain minute bodies..which..may be termed microsomes or microsomata.
b. Any of the particles which constitute the lightest fraction obtained by ultracentrifugation of cell contents under specific conditions and which are believed to be formed from fragmented endoplasmic reticulum and attached ribosomes; also (esp. formerly), a ribosome in an intact cell.
1943A. Claude in Science 21 May 453/2 In order to differentiate the small particles from the other, already identified elements of the cell, it may be convenient in the future to refer to this new component under a descriptive name which would be specific. For this purpose the term microsome appears to be the most appropriate. The term microsome..was applied originally by Hanstein (1880) to any granules, as seen in living protoplasm. The use of the word was progressively narrowed down, being retained as a general term to designate any small granules of undefined nature. Under these conditions, it seems proper to suggest that the term microsome..should be restricted to designate the small particles exclusively. 1955Federation Proc. XIV. 262/1 It was found that the microsomes are morphologically identical with the vesicular and tubular elements of the endoplasmic reticula (ER) of intact cells. 1957C. P. Swanson Cytol. & Cytogenetics (1958) ii. 32 (caption) The structure of the cytoplasm of rat liver cells as revealed by electron microscopy, showing the endoplasmic reticulum..and the attached particles (microsomes) which are between 100 and 200 A in diameter. 1960New Biol. XXXI. 30 The microsomes themselves, which are obtained after the cell has been broken down, are vesicles made of two components: a membrane, which is rich in proteins and lipids, and very small granules... These small particles contain as much as 40–50 per cent RNA and..most of the cellular RNA is present in them. 1968L. L. Langley Cell Function (ed. 2) i. 9 The endoplasmic reticulum is seen..to form a series of small canals through the cytoplasm... Closely associated with the membranes which line the canals are tiny granules termed microsomes. Because they contain such a high concentration of RNA, they are often referred to as ribosomes. 1970Ambrose & Easty Cell Biol. v. 164 Microsomes are in fact small spherical vesicles formed from disrupted endoplasmic reticulum. The microsomal fraction of homogenized cells may also contain ribosomes.
So microˈsomatous a., epithet applied to animals of minute size (Mayne Expos. Lex. 1856). |