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Lung parenchyma showing damage due to large subpleural bullae. Parenchyma (/ p ə ˈ r ɛ ŋ k ɪ m ə /) [1] [2] is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology, it is the tissue that fills the interior of flatworms. In botany, it is some layers in the cross-section of the leaf. [3]
In plant anatomy, there are two main types of sieve elements. Companion cells and sieve cells originate from meristems , which are tissues that actively divide throughout a plant's lifetime. They are similar to the development of xylem , a water conducting tissue in plants whose main function is also transportation in the plant vascular system ...
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
These are sclereids with thick cell walls and numerous pits, resembling adjacent parenchyma cells. This resemblance suggests that these sclereids are originally parenchyma cells, but are so sclerified that they are now sclereid cells rather than parenchyma cells. These sclereids are an example of brachysclereids, or stone cells.
Three-dimensional schematic of the interstitium, a fluid-filled space supported by a network of collagen. The interstitium is a contiguous fluid-filled space existing between a structural barrier, such as a cell membrane or the skin, and internal structures, such as organs, including muscles and the circulatory system.
The pulmonary pleura covers the entire lung parenchyma. It meets the mediastinal pleura at the root of the lung ("hilum") through a smooth fold known as pleural reflection . A bell sleeve -like extension of the pulmonary pleura hanging under to the hilum is known as the pulmonary ligament .
Cross-section of a flax plant stem: 1. Pith 2. Protoxylem 3. Xylem I 4. Phloem I 5. Sclerenchyma 6. Cortex 7. Epidermis. In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. [1]