| y | Something shaped like the letter Y; a forked piece resembling in form the letter Y. Specifically: <zoology> Y moth, a handsome European noctuid moth Plusia gamma) which has a bright, silvery mark, shaped like the letter Y, on each of the fore wings. Its larva, which is green with five dorsal white species, feeds on the cabbage, turnip, bean, etc. (11 Mar 1998) |
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| Y body | A single fluorescent spot originating in the long arm of the Y chromosome and visible in somatic nuclei of buccal smears. (05 Mar 2000) |
| Y cartilage | Y-shaped cartilage, the connecting cartilage for the ilium, ischium, and pubis; it extends through the acetabulum. Synonym: hypsiloid cartilage. (05 Mar 2000) |
| y chromatin | Brilliantly fluorescent body seen in cells stained with the dye quinacrine which lights up the y chromosomes most brightly. (12 Dec 1998) |
| Y chromosome | <genetics> The small chromosome that is male-determining in most mammal species and found only in the heterogametic sex. Thus in mammals the male has one Y chromosome and one X chromosome. One region of the Y chromosome, the pseudoautosomal region, is homologous to and pairs with the X chromosome. The primary determinant of male sexual development is found on the unpaired, differentiated segment of the Y chromosome. It carries few other genes besides those dictating sperm development and triggering appropriate hormonal output. (18 Nov 1997) |
| y map | The array of genes on the y chromosome. Once thought to be a genetic wasteland, the y now is known to contain at least 20 genes, some of them unique to the y including the male-determining gene and male fitness genes that are active only in the testis and are thought responsible for the formation of sperm. Other genes on the y have counterparts on the x chromosome, are active in many body tissues and play crucial housekeeping roles with the cell. (12 Dec 1998) |
| y wave | The wave in the atrial and venous pulse curves reflecting rapid filling of the ventricles just after the atrioventricular valves open. (05 Mar 2000) |
| y-angle | In craniometry, the angle at the inion formed by lines drawn from the hormion and the lambda. Synonym: hypsiloid angle. (05 Mar 2000) |
| Y-axis | A cephalometric indicator of the vertical and horizontal coordinates of mandibular growth expressed in degrees of the inferior facial angle formed by the intersection of the sella-gnathion plane with the Frankfort horizontal plane. (05 Mar 2000) |
| Y-linkage | The state of a genetic factor (gene) being borne on the Y chromosome. This idea is analogous with X-linkage but since the Y chromosome does not fully take part in chiasma formation and recombination, it not amenable to analysis by conventional linkage methods. Little is known about its content. There is a gene for the H-Y antigen, and indirect arguments suggest that there is a principle that determines the formation of the testis and masculinization of the foetus but its localization, though narrowing the limits, remains elusive. (05 Mar 2000) |
| y-linked | A gene on the Y chromosome. A y-linked gene is by necessity passed from father to son. (12 Dec 1998) |
| Y-linked gene | A gene located on a Y chromosome. Synonym: holandric gene. (05 Mar 2000) |
| y-linked inheritance | Inheritance by genes on the y chromosome. Also called holandric inheritance. (12 Dec 1998) |
| Y-linked locus | Any (haploid) locus that in normal karyotypes is borne on the Y chromosome. The known content is so far small. (05 Mar 2000) |
| Y-shaped ligament | <anatomy> A triangular ligament attached by its apex to the anterior inferior spine of the ilium and rim of the acetabulum, and by its base to the anterior intertrochanteric line of the femur; the strong medial band is attached to the lower part of the intertrochanteric line; the strong lateral part is fixed to the tubercle at the upper part of this line; the bands diverge, forming a Y-like figure with a weak area between; among the strongest of the body's ligaments, it limits extension at the hip joint. Synonym: ligamentum iliofemorale, Bertin's ligament, Bigelow's ligament, hypsiloid ligament, Y-shaped ligament. (05 Mar 2000) |