| anal pit | 1. An ectodermally lined depression under the root of the tail, adjacent to the terminal part of the embryonic hindgut; at its bottom, proctodeal ectoderm and cloacal endoderm form the cloacal plate. When this epithelial plate ruptures, the anal and urogenital external orifices are established. Synonym: anal pit. 2. Terminal portion of the insect alimentary canal, extending from the pylorus (area of malpighian tubule attachment) to the anal opening; in certain diptera (flies) and other insects, the proctodeum is divided into a tubular anterior intestine and an enlarged posterior intestine, or rectum, ending at the anus. Origin: L. Fr. G. Proktos, anus + hodaios, on the way, fr. Hodos, a way (05 Mar 2000) |
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| anal plate | The anal portion of the cloacal plate. (05 Mar 2000) |
| anal reflex | Contraction of the internal sphincter gripping the finger passed into the rectum. (05 Mar 2000) |
| anal region | The posterior portion of the perineal region through which the anal canal opens; bounded by a line through both isehial tuberosities, the sacrotuberous ligaments and the coccyx. Synonym: regio analis, anal region. (05 Mar 2000) |
| anal sac | A vesicular cutaneous invagination opening by a duct on each side of the anal canal in carnivores (best developed in skunks, but absent in some bears, the raccoon, kinkajou, coati, and sea otter), each lying between the external and internal anal sphincter muscles, which aid in emptying the contents. The sac stores odouriferous scent markers produced by glands that line its wall or duct; frequently the sac becomes impacted in the dog or cat, requiring manual emptying. (05 Mar 2000) |
| anal sacs | Two sacs opening on either side of the anus near the junction of the mucous membrane and skin in carnivores. The glandular lining produces a gray or brown sebaceous secretion having an unpleasant odour. The sac ducts sometimes become occluded and the secretion accumulates. This leads to irritation that the animal attempts to relieve by rubbing its anus along the ground. The sacs may subsequently become infected and abscessed. (12 Dec 1998) |
| anal sinuses | The grooves between the anal columns. Synonym: Morgagni's sinus. Pockets or crypts in the columnar zone of the anal canal between the anocutaneous line and the anorectal line; the sinuses give the mucosa a scalloped appearance. Synonym: sinus anales, anal crypts, Morgagni's crypts, rectal sinuses. (05 Mar 2000) |
| anal sphincter | See: external anal sphincter, internal anal sphincter. (05 Mar 2000) |
| anal triangle | The posterior portion of the perineal region through which the anal canal opens; bounded by a line through both isehial tuberosities, the sacrotuberous ligaments and the coccyx. Synonym: regio analis, anal region. (05 Mar 2000) |
| anal valves | Delicate crescent-shaped mucosal folds that pass between the lower ends of neighboring anal columns; the small pocket thus formed is an anal sinus. Synonym: valvulae anales, Morgagni's valves. (05 Mar 2000) |
| anal verge | The transitional zone between the moist, hairless, modified skin of the anal canal and the perianal skin. (05 Mar 2000) |
| analbuminaemia | Absence of albumin from the serum. Origin: G. An-priv. + albumin + G. Haima, blood (05 Mar 2000) |
| analcime | <chemical> A white or flesh-red mineral, of the zeolite, occurring in isometric crystals. By friction, it acquires a weak electricity; hence its name. Origin: Gr. Priv. + strong, strength: cf. F. Analcime. Source: Websters Dictionary (01 Mar 1998) |
| analemma | 1. <chemistry> An orthographic projection of the sphere on the plane of the meridian, the eye being supposed at an infinite distance, and in the east or west point of the horizon. 2. An instrument of wood or brass, on which this projection of the sphere is made, having a movable horizon or cursor; formerly much used in solving some common astronomical problems. 3. A scale of the sun's declination for each day of the year, drawn across the torrid zone on an artificial terrestrial globe. Origin: L. Analemma a sun dial on a pedestal, showing the latitude and meridian of a place, Gr. A support, or thing supported, a sun dial, fr. To take up; + to take. Source: Websters Dictionary (01 Mar 1998) |
| analepsy | 1. <medicine> Recovery of strength after sickness. 2. <neurology> A species of epileptic attack, originating from gastric disorder. See: Analemma. Origin: Gr. A taking up, or again, recovery, from. Source: Websters Dictionary (01 Mar 1998) |