| ameloblastoma | <oncology, tumour> A malignant jaw tumour (adamantinoma) which stems from the ameloblasts, cells which form tooth enamel. (09 Oct 1997) |
|---|---|
| pigmented ameloblastoma | A benign neoplasm of neuroectodermal origin that most often involves the anterior maxilla of infants in the first year of life. It presents clinically as a rapidly growing blue-black lesion producing a destructive radiolucency; histologically, it is characterised by small round undifferentiated tumour cells interspersed with larger polyhedral melanin-producing cells arranged in an alveolar configuration. Synonym: melanoameloblastoma, pigmented ameloblastoma, pigmented epulis, progonoma of jaw, retinal anlage tumour. (05 Mar 2000) |
| pituitary ameloblastoma | <oncology, tumour> A form of primary brain tumour which develops in the pituitary gland. These tumours often secrete increased quantities of pituitary hormones (for example growth hormone) which can result in conditions such as gigantism and acromegaly. They are often benign and rare and comprise less than 5% of childhood brain tumours. Other symptoms include vision changes, headache and weight gain. Treatment often includes a combination of surgery and radiation therapy. (27 Sep 1997) |
| plexiform | Weblike, or resembling or forming a plexus. Origin: plexus + L. Forma, form (05 Mar 2000) |
| plexiform layer | molecular layer |
| plexiform layer of cerebral cortex | Layer 1 of the cortex cerebri. Synonym: plexiform layer of cerebral cortex. (05 Mar 2000) |
| plexiform layers of retina | Layer's of the retina where synapses occur; in the external layer, processes of rods and cones synapse with bipolar neuron dendrites; in the internal layer, axon terminals of bipolar cells synapse with ganglion cell dendrites. See: retina. Synonym: stratum plexiforme externum et internum retinae. (05 Mar 2000) |
| plexiform neuroma | plexiform neurofibroma |
| neurofibroma, plexiform | A type of neurofibroma representing an anomaly rather than a true neoplasm, in which the proliferation of schwann cells occurs from the inner aspect of the nerve sheath, thereby resulting in an irregularly thickened, distorted, tortuous structure. In some instances the process extends along the course of the nerve and may eventually involve the spinal roots and the spinal cord. (12 Dec 1998) |