| primitive streak | An ectodermal ridge in the midline at the caudal end of the embryonic disk from which arises the intraembryonic mesoderm; achieved by inward and then lateral migration of cells; in human embryos, it appears on day 15 and gives a cephalocaudal axis to the developing embryo. Synonym: germinal streak. (05 Mar 2000) |
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| vascular-streak dieback | A fungal disease of the cacaotree caused by Oncobasidium theobromae. (09 Oct 1997) |
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| germinal streak | An ectodermal ridge in the midline at the caudal end of the embryonic disk from which arises the intraembryonic mesoderm; achieved by inward and then lateral migration of cells; in human embryos, it appears on day 15 and gives a cephalocaudal axis to the developing embryo. Synonym: germinal streak. (05 Mar 2000) |
| gonadal streak | A form of aplasia in which the ovary is replaced by a functionless tissue, as found in Turner's syndrome. Synonym: streak gonad. (05 Mar 2000) |
| meningitic streak | A line of redness resulting from drawing a point across the skin, especially notable in cases of meningitis. Synonym: tache cerebrale, tache meningeale, Trousseau's spot. (05 Mar 2000) |
| streak | 1. A line or long mark of a different colour from the ground; a stripe; a vein. "What mean those coloured streaks in heaven?" (Milton) 2. A strake. 3. <chemical> The fine powder or mark yielded by a mineral when scratched or rubbed against a harder surface, the colour of which is sometimes a distinguishing character. 4. The rung or round of a ladder. Origin: OE. Streke; akin to D. Streek a line, stroke, G. Strich, AS. Strica, Sw. Strek, Dan. Streg, Goth. Stricks, and E. Strike, stroke. See Strike, Stroke, and cf. Strake. Source: Websters Dictionary (01 Mar 1998) |
| streak culture | A culture produced by lightly stroking an inoculating needle or loop with inoculum over the surface of a solid medium. (05 Mar 2000) |
| streak gonad | A form of aplasia in which the ovary is replaced by a functionless tissue, as found in Turner's syndrome. Synonym: streak gonad. (05 Mar 2000) |
| streak hyperostosis | A hypertrophying and condensing osteitis which tends to run in longitudinal streaks or columns, like wax drippings on a candle, and which involves a number of the long bones. Synonym: flowing hyperostosis, streak hyperostosis. Origin: rheo-+ G. Osteon, bone, + -osis, condition (05 Mar 2000) |
| fatty streak | <pathology> Superficial fatty patch in the artery wall caused by the accumulation of cholesterol and cholesterol oleate in distended foam cells. (18 Nov 1997) |
| primitive | Undeveloped or in early stages of development, undifferentiated. (16 Dec 1997) |
| primitive aorta | The paired aortic primordia in young embryos. (05 Mar 2000) |
| primitive chorion | The chorion before its villi are well formed. Synonym: previllous chorion. (05 Mar 2000) |
| primitive costal arches | Arch's formed in the thoracic region of the vertebral column in the embryo from the costal processes or costal elements which give rise to the ribs. (05 Mar 2000) |
| primitive erythroblast | <cell biology> Large cell with euchromatic nucleus found in mammalian embryos. In the mouse, the cells are located in the yolk sac and are responsible for early production of erythrocytes with foetal haemoglobin. (18 Nov 1997) |
| primitive furrow | The median depression in the primitive streak flanked by the primitive ridges. Synonym: primitive furrow. (05 Mar 2000) |