nucellus
/nju:'seləs/
Học thuậtThân thiện
Definition
- Noun:
- The central part of a plant ovule; contains the embryo sac: The
nucellusis the tissue within the ovule of a seed plant that is surrounded by the integuments. It functions as the nutritive tissue for the developing embryo sac and, subsequently, the embryo.
Usage
- The is a botanical term used specifically in plant anatomy and reproduction. It is the core structure within an ovule where the megaspore mother cell undergoes meiosis to form the embryo sac.
Examples
- Noun:
- The
nucellusprovides nourishment to the developing female gametophyte. - In some plants, the
nucelluspersists and becomes part of the seed, known as perisperm.
Advanced Usage
- "Degenerate nucellus": In many angiosperms, the is absorbed by the developing embryo sac and endosperm.
- After fertilization, the
nucellusoften degenerates as the endosperm takes over its nutritive role.
Variants and Related Words
- Nucellar (adj): Pertaining to or derived from the nucellus.
- The nucellar tissue was visible under the microscope.
Synonyms
- Megasporangium: In botanical terms, the ovule (which includes the nucellus, integuments, and embryo sac) is considered a megasporangium. The is the sporangium wall tissue.
Noun
- central part of a plant ovule; contains the embryo sac