microsomen.

1881 Jrnl. Royal Microsc. Soc. 1 475 Imbedded in the protoplasm are almost always strongly refractive granules, which assume a darker tincture—the ‘microsomes’ of Hanstein.

1887 H. M. Ward tr. J. von Sachs Lect. Physiol. Plants i. vi. 79 This substance [sc. the protoplasm]..is thickly set with very numerous small granules (microsomes).

1900 A. J. Ewart tr. W. Pfeffer Physiol. Plants I. ii. 43 Cytoplasm may contain minute bodies..which..may be termed microsomes or microsomata.

1923 Science 9 Mar. 282/1 It is probable that both macrosomes and microsomes may be of several, perhaps many, different kinds.

1935 Bot. Gaz. 97 198 They have been variously termed microsomes, spherosomes, cytosomes, lipoid granules, fat globules, etc.

1943 A. Claude in Science 21 May 453/2 The term microsome..was applied originally by Hanstein (1880) to any granules, as seen in living protoplasm.

1943 A. 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.

1955 Federation Proc. (Federation Amer. Soc. Exper. Biol.) 14 262/1 It was found that the microsomes are morphologically identical with the vesicular and tubular elements of the endoplasmic reticula (ER) of intact cells.

1960 New Biol. 31 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.

1968 L. 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.

1970 E. J. Ambrose & D. M. 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.

1990 EMBO Jrnl. 9 2392/1 The products were analyzed for integration or translocation into dog pancreas microsomes.