释义 |
DictionarySeeovumhuman ovum HUMAN OVUMhuman ovumThe female gamete, required for reproduction. The ovum develops from an oogonium within the graafian follicle of the ovary and matures through the meiotic process of oogenesis. A mature ovum is about 0.13 to 0.14 mm (0.0051 to 0.0055 in) in diameter. At ovulation, the ovum is bounded by a translucent cellular membrane (the zona pellucida), which is connected to a layer of follicular cells (the corona radiata); these cells enclose the cytoplasm, nuclei, and chromatin material. The exact time during which a human ovum is capable of fertilization and further development before degenerating is not known; however, it is probably 24 hr. See: illustration; oogenesis; ovulationSee also: ovum |