| paraventricular nucleus | A triangular group of large magnocellular neurons in the periventricular zone of the anterior half of the hypothalamus. The cells of the nucleus are similar to those of the supraoptic nucleus; the axons of about 20% of their number join in the formation of the supraopticohypophysial tract and are functionally associated with the posterior lobe of the hypophysis; they project fibres to the brainstem nuclei (dorsal motor nucleus and solitary nucleus) and to the intermediolateral cell column of the spinal cord at thoracic, lumbar, and spinal levels; similar descending autonomic fibres arise from the lateral and posterior hypothalamic nuclei. Synonym: nucleus paraventricularis, filiform nucleus, nucleus filiformis. (05 Mar 2000) |
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| germ nucleus | <cell biology> The smaller nucleus in ciliate protozoans, fully active in inheritance and passed after meiosis to conjugating pairs. Gives rise to the macronucleus or macronuclei. Genes in the micronucleus are not actively transcribed. (18 Nov 1997) |
| masticatory nucleus | <anatomy, nerve> A group of motor neurons innervating the muscles of mastication (masseter, temporalis, internal and external pterygoid muscles) and the musculi tensor tympani and tensor veli palatini. The nucleus lies in the upper pontine tegmentum medial to the main sensory nucleus of the trigeminus. Synonym: nucleus motorius nervi trigemini, masticatory nucleus, motor nucleus of trigeminus, nucleus masticatorius. (05 Mar 2000) |
| red nucleus | A distinctive oval nucleus (pink in fresh specimens because of an iron-containing pigment in many of the cells) centrally placed in the upper mesencephalic reticular formation. It receives fibres from the deep cerebellar nuclei and cerebral cortex and projects fibres to the cerebellum, brainstem, spinal cord, and probably to the thalamus. The nucleus is divided into two regions: pars magnocellularis and pars parvocellularis. (12 Dec 1998) |
| vestibular nucleus | One of a group of four main nuclei that includes: the lateral vestibular nucleus (Deiters' nucleus), medial vestibular nucleus (Schwalbe's nucleus), superior vestibular nucleus (Bechterew's nucleus), and inferior vestibular nucleus, located in the lateral region of the hindbrain beneath the floor of the rhomboid fossa. They receive primary fibres of the vestibular nerve, are reciprocally connected with the flocculonodular lobe of the cerebellum, and project by way of the medial longitudinal fasciculus to the abducens, trochlear, and oculomotor nuclei and to the ventral horn of the spinal cord. The lateral vestibular nucleus projects to the ipsilateral ventral horn of the spinal cord by the vestibulospinal tract. Synonym: nucleus vestibularis. (05 Mar 2000) |
| gigantocellular nucleus of medulla oblongata | One of the three major nuclei of the reticular formation of the brainstem. Synonym: nucleus gigantocellularis medullae oblongatae. (05 Mar 2000) |
| reduction nucleus | A nucleus that degenerates in the cell during the changes incident to fertilization. (05 Mar 2000) |
| caudate nucleus | Elongated gray mass of the neostriatum located adjacent to the lateral ventricle of the brain. (12 Dec 1998) |
| globosus nucleus | A group of two or three small masses of gray substance in the white central core of the cerebellum, medial to the emboliform nucleus; receives axons of Purkinje cells of the intermediate area of the cerebellar cortex; axons of these cells exit the cerebellum via the superior cerebellar peduncle. Synonym: nucleus globosus, spherical nucleus. (05 Mar 2000) |
| medial accessory olivary nucleus | A detached part of the olivary nucleus medial to the latter's main body, against the lateral side of the medial lemniscus and pyramidal tract. Synonym: nucleus olivaris accessorius medialis. (05 Mar 2000) |
| medial central nucleus of thalamus | A small cell group in the interthalamic adhesion of the thalamus, occupying the midline region of the internal medullary lamina, between the left and the right paracentral nucleus. Synonym: nucleus medialis centralis thalami. (05 Mar 2000) |
| medial nucleus of thalamus | A large, composite cell group in the dorsomedial region of the thalamus having reciprocal connections with the entire extent of the frontal cortex anterior to the motor cortex (area 4) and premotor cortex (area 6). The afferent connections of the medial nucleus also include projections from the olfactory cortex and amygdala. Synonym: nucleus medialis thalami, dorsomedial nucleus, mediodorsal nucleus. (05 Mar 2000) |
| medial preoptic nucleus | A group of nerve cells forming the medial zone of the preoptic region. Synonym: nucleus preopticus medialis. (05 Mar 2000) |
| medial vestibular nucleus | Nucleus vestibularis medialis. See: vestibular nucleus. (05 Mar 2000) |
| cell nucleus | Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. (12 Dec 1998) |