| 释义 |
tapetumenUK
ta·pe·tum T0043200 (tə-pē′təm)n. pl. ta·pe·ta (-tə) 1. Botany A nutritive tissue that surrounds certain developing spores, particularly the microspores within an anther.2. Anatomy a. A reflective membrane in the back of the eye of many animals that are active during low-light conditions.b. A layer of fibers of the corpus callosum forming the roof of part of the lateral ventricle of the brain.
[Medieval Latin tapētum, coverlet, from Latin tapēte, *tapētum, from Greek tapēs, tapēt-; see tapestry.]
ta·pe′tal (-pēt′l) adj.tapetum (təˈpiːtəm) n, pl -ta (-tə) 1. (Botany) a layer of nutritive cells in the sporangia of ferns and anthers of flowering plants that surrounds developing spore cells2. (Zoology) a. a membranous reflecting layer of cells in the choroid of the eye of nocturnal vertebratesb. a similar structure in the eyes of certain nocturnal insects3. (Anatomy) anatomy a covering layer of cells behind the retina of the eye[C18: from New Latin, from Medieval Latin: covering, from Latin tapēte carpet, from Greek tapēs carpet] taˈpetal adjta•pe•tum (təˈpi təm)
n., pl. -ta (-tə). 1. Bot. a layer of nutritive tissue in a developing sporangium or anther that is absorbed as the spore matures. 2. Anat. any of certain membranous layers or layered coverings, as in the choroid coat in certain animals. [1705–15; < New Latin; Medieval Latin tapētum coverlet (Latin, only pl.) < Greek tapēt-, s. of tápēs carpet] ta•pe′tal, adj. TapetumenUK
tapetum[tə′pēd·əm] (botany) A layer of nutritive cells surrounding the spore mother cells in the sporangium in higher plants; it is broken down to provide nourishment for developing spores. (neuroscience) A reflecting layer in the choroid coat behind the neural retina, chiefly in the eyes of nocturnal mammals. A tract of nerve fibers forming part of the roof of each lateral ventricle in the vertebrate brain. Tapetum a layer (occasionally several layers) of cells in the sporangia of the majority of higher plants; it is rich in nutrients and physiologically active substances. The tapetum may originate from the archespore, as in leptosporangiate ferns and selaginellas. It may be the inner layer of the sporangium wall, as in eusporangiate ferns, plants of the order Lycopodiales, and plants of the genus Equisetum, or the inner layer of a microsporangium, as in seed plants. The substances in tapetum cells are used by the developing sporocytes and spores; in seed plants they are used by the pollen grains as well. The tapetum cells either form a periplasmodium, or amoeboid tapetum, or they maintain their position, forming a secretory tapetum. There is no tapetum in the sporangia of Psilotophyta or Isoëtales. tapetumenUK
tapetum [tah-pe´tum] (L.) 1. a covering structure or layer of cells.2. a stratum in the human brain composed of fibers from the body and splenium of the corpus callosum sweeping around the lateral ventricle.tapetum lu´cidum the iridescent epithelium of the choroid of animals that gives their eyes the property of shining in the dark.ta·pe·tum, pl. ta·pe·ta (tă-pē'tŭm, -tă), [TA] 1. In general, any membranous layer or covering. 2. neuroanatomy a thin sheet of fibers in the lateral wall of the temporal and occipital horns of the lateral ventricle, continuous with the corpus callosum. Synonym(s): Fielding membrane, membrana versicolor3. A dense layer in the choroidea of the eye of many mammalian species, including the cat and dog but not humans, which forms a discrete or diffuse area of reflective cells, rodlets, and fibers; its strong light-reflecting properties cause the metallic hue and light-glow of such eyes in the dark. [L. tapeta, a carpet] tapetum (tə-pē′təm)n. pl. tape·ta (-tə) Anatomy a. A reflective membrane in the back of the eye of many animals that are active during low-light conditions.b. A layer of fibers of the corpus callosum forming the roof of part of the lateral ventricle of the brain.
ta·pe′tal (-pēt′l) adj.ta·pe·tum, pl. tapeta (tă-pē'tŭm, -tă) [TA] 1. In general, any membranous layer or covering. 2. [TA] neuroanatomy A thin sheet of fibers in the lateral wall of the temporal and occipital horns of the lateral ventricle, continuous with the corpus callosum. [L. tapeta, a carpet]tapetum - a nutritive layer surrounding those cells which will become MICROSPORES. The tapetum is found in a wide range of vascular plants, from FERNS to ANGIOSPERMS. In the latter, a tapetal layer is found in the pollen sacs of the ANTHER.
- a layer of specialized reflective cells in the choroid of the EYE, especially noticeable in the eyes of cats.
Fielding, George H., English anatomist, 1801-1871. Fielding membrane - in neuroanatomy, a thin sheet of fibers in the lateral wall of the temporal and occipital horns of the lateral ventricle, continuous with the corpus callosum. Synonym(s): tapetum |