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How does a plant embryo develop from a fertilized egg?
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plant development
The life cycle of the fern. (1) Clusters (sori) of sporangia (spore cases) grow on the undersurface of mature fern leaves. (2) Released from its spore case, the haploid spore is carried to the ground, where it germinates into a tiny, usually heart-shaped, gametophyte (gamete-producing structure), anchored to the ground by rhizoids (rootlike projections). (3) Under moist conditions, mature sperm are released from the antheridia and swim to the egg-producing archegonia that have formed on the gametophyte's lower surface. (4) When fertilization occurs, a zygote forms and develops into an embryo within the archegonium. (5) The embryo eventually grows larger than the gametophyte and becomes a sporophyte.
In vascular plants, the development of an embryo from a fertilized egg, or zygote, is known as embryogenesis. This process typically begins with the first cell division of the zygote, which establishes a primary polarization that dictates the future organization of the plant.1
While developmental details vary across plant groups, the general process involves:
- Early Cleavage: The zygote divides into daughter cells. In many plants, this includes the formation of temporary structures like the suspensor and foot, which assist in nutrient absorption during early growth.12
- Organ Specification: Through subsequent divisions, specific cell lineages are established to form the primary organs of the sporophyte, including the root, stem, and leaves.13
- Tissue Differentiation: As the embryo grows, it develops apical meristems—regions of undifferentiated, actively dividing cells—at the ends of its bipolar axis. These meristems eventually differentiate into primary tissue systems, such as the epidermis, ground tissues, and vascular tissues.4
In angiosperms, this process is often supported by double fertilization, where one sperm cell forms the zygote and another contributes to the endosperm, a nutritive tissue that surrounds the developing embryo.56