| muscle spindle | A specialised muscle fibre found in tetrapod vertebrates. A bundle of muscle fibres is innervated by sensory neurons. Stretching the muscle causes the neurons to fire, the muscle spindle thus functions as a stretch receptor. (18 Nov 1997) |
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| muscle spindles | Mechanoreceptors found between skeletal muscle fibres. Muscle spindles are arranged in parallel with muscle fibres and respond to the passive stretch of the muscle, but cease to discharge if the muscle contracts isotonically, thus signaling muscle length. The muscle spindles are the receptors responsible for the stretch or myotactic reflex (reflex, stretch). (12 Dec 1998) |
| spindle-shaped muscle | <anatomy> One that has a fleshy belly, tapering at either extremity. Synonym: musculus fusiformis, spindle-shaped muscle. (05 Mar 2000) |
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| aortic spindle | A fusiform dilation of the aorta immediately beyond the isthmus. Synonym: His' spindle. (05 Mar 2000) |
| central spindle | A central group of microtubules (continuous fibres) that course uninterrupted, between the asters, in contrast to the microtubules attached to the individual chromosomes (s. Fibres). (05 Mar 2000) |
| meiotic spindle | The meiotic equivalent of the mitotic spindle. (18 Nov 1997) |
| cleavage spindle | The spindle formed during the cleavage of a zygote or its blastomeres. (05 Mar 2000) |
| mitotic spindle | See: spindle and mitosis. (18 Nov 1997) |
| mitotic spindle apparatus | An organelle consisting of three components: 1) the astral microtubules, which form around each centrosome and extend to the periphery; 2) the polar microtubules which extend from one spindle pole to the equator; and 3) the kinetochore microtubules, which connect the centromeres of the various chromosomes to either centrosome. (12 Dec 1998) |
| His' spindle | A fusiform dilation of the aorta immediately beyond the isthmus. Synonym: His' spindle. (05 Mar 2000) |
| sleep spindle | The electroencephalographic record of 14-per-second bursts of wave frequency seen on EEG examination. (05 Mar 2000) |
| spindle | See: mitosis, spindle fibre. (18 Nov 1997) |
| spindle cataract | A cataract in which the opacity is fusiform, extending from one pole to the other. Synonym: fusiform cataract. (05 Mar 2000) |
| spindle cell | A fusiform cell, such as those in the deeper layers of the cerebral cortex. (05 Mar 2000) |
| spindle cell carcinoma | <tumour> A carcinoma composed of elongated cells, frequently a poorly differentiated squamous cell carcinoma which may be difficult to distinguish from a sarcoma. Synonym: sarcomatoid carcinoma. (05 Mar 2000) |
| spindle-celled layer | Layer 6 of the cortex cerebri. Synonym: multiform layer, polymorphous layer, spindle-celled layer. (05 Mar 2000) |
| spindle cell lipoma | <tumour> A microscopically distinctive form of lipoma in which adipose tissue is infiltrated by fibroblasts and collagen; usually found in the shoulder or neck of elderly men. (05 Mar 2000) |