11 Trending Words of 2014
ovule o·vule (ō'vyōōl, ŏv'yōōl)
A small or immature ovum of a mammal.
A small egglike structure. Also called ovulum.
The female reproductive structure that develops into a seed in a seed-bearing plant. An ovule consists of a megasporangium surrounded by one or two layers of tissue called integuments. The megasporangium produces spores that develop into megagametophytes. These megagametophytes remain within the tissues of the ovule and produce one or more egg cells. Sperm from pollen grains enter the ovule through an opening called a micropyle and fertilize the egg cells. The resulting embryo then begins to develop within the ovule, which becomes a seed. Among the conifers and cycads, the ovules are typically found in pairs on scales in the female cones. The ovules of angiosperms are contained in a structure called the ovary within in the flower. See more at flower, gametophyte, megasporogenesis, pollination.
plant structure that develops into a seed when fertilized. In gymnosperms (conifers and allies) the ovules lie uncovered on the scales of the cone. In angiosperms (flowering plants), one or more ovules are enclosed by the ovary (portion of the carpel, or female reproductive organ). Each ovule is attached by its base to the stalk (funiculus) that bears it. A mature angiosperm ovule consists of a food tissue covered by one or two future seed coats. A small opening (the micropyle) in the integuments at the apex of the ovule permits the pollen tube to enter and discharge its sperm nuclei into the embryo sac, a large oval cell in which fertilization and development occur. Variations in form and position of the ovule are significant in plant classification: orthotropous ovules stand out straight into the cavity of the ovary; campylotropous ovules are at right angles to the funiculus; anatropous ovules are directed back toward the funiculus. Intermediate forms also occur.