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Meristem
In cell biology, the meristem is a structure composed of specialized tissue found in plants, consisting of stem cells, known as meristematic cells, which are undifferentiated cells capable of continuous cellular division. These meristematic cells play a fundamental role in plant growth, regeneration, and acclimatization, as they serve as the source of all differentiated plant tissues and organs. They contribute to the formation of structures such as fruits, leaves, and seeds, as well as supportive tissues like stems and roots. Meristematic cells are totipotent, meaning they have the ability to differentiate into any plant cell type. As they divide, they generate new cells, some of which remain meristematic cells while others differentiate into specialized cells that typically lose the ability to divide or produce new cell types. Due to their active division and undifferentiated nature, meristematic cells form the foundation for the formation of new plant organs and the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Tissue
In biology, tissue is an assembly of similar cells and their extracellular matrix from the same embryonic origin that together carry out a specific function. Tissues occupy a biological organizational level between cells and a complete organ. Accordingly, organs are formed by the functional grouping together of multiple tissues. The English word "tissue" derives from the French word "", the past participle of the verb tisser, "to weave". The study of tissues is known as histology or, in connection with disease, as histopathology. Xavier Bichat is considered as the "Father of Histology". Plant histology is studied in both plant anatomy and physiology. The classical tools for studying tissues are the paraffin block in which tissue is embedded and then sectioned, the histological stain, and the optical microscope. Developments in electron microscopy, immunofluorescence, and the use of frozen tissue-sections have enhanced the detail that can be observed in tissues. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Growth
Important structures in plant development are buds, Shoot (botany), shoots, roots, leaf, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant always has embryonic tissues. By contrast, an animal embryo will very early produce all of the body parts that it will ever have in its life. When the animal is born (or hatches from its egg), it has all its body parts and from that point will only grow larger and more mature. However, both plants and animals pass through a phylotypic stage that evolved independently and that causes a developmental constraint limiting morphological diversification. According to plant physiology, plant physiologist A. Carl Leopold, the properties of organization seen in a plant are emergence, emergent properties which are more than the sum of the individual parts. "The assembly of these tissues and functions into an integrated multicel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vascular Cambium
The vascular cambium is the main growth tissue in the stems and roots of many plants exhibiting secondary growth, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain other vascular plants. It produces secondary xylem inwards, towards the pith, and secondary phloem outwards, towards the bark. Generally, more secondary xylem is produced than secondary phloem. In herbaceous plants, it occurs in the vascular bundles which are often arranged like beads on a necklace forming an interrupted ring inside the stem. In woody plants, it forms a cylinder of unspecialized meristem cells, as a continuous ring from which the new tissues are grown. Unlike the xylem and phloem, it does not transport water, minerals or food through the plant. Other names for the vascular cambium are the main cambium, wood cambium, or bifacial cambium. Occurrence Vascular cambia are found in all seed plants except for five angiosperm lineages whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phloem
Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is called translocation. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Ancient Greek word (''phloiós''), meaning "bark". The term was introduced by Carl Nägeli in 1858. Different types of phloem can be distinguished. The early phloem formed in the growth apices is called protophloem. Protophloem eventually becomes obliterated once it connects to the durable phloem in mature organs, the metaphloem. Further, secondary phloem is formed during the thickening of stem structures. Structure Phloem tissue consists of conducting cells, generally called sieve elements, parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells and supportive cells, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Cell Wall
A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. While absent in many eukaryotes, including animals, cell walls are prevalent in other organisms such as fungi, algae and plants, and are commonly found in most prokaryotes, with the exception of mollicute bacteria. The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In land plants, the primary cell wall comprises polysaccharides like cellulose, hemicelluloses, and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit cell walls composed of glycoproteins and polysaccharides, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Cell
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells, which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type. In mammals, roughly 50 to 150 cells make up the inner cell mass during the blastocyst stage of embryonic development, around days 5–14. These have stem-cell capability. '' In vivo'', they eventually differentiate into all of the body's cell types (making them pluripotent). This process starts with the differentiation into the three germ layers – the ectoderm, mesoderm and endoderm – at the gastrulation stage. However, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellular Differentiation
Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover. Some differentiation occurs in response to antigen exposure. Differentiation dramatically changes a cell's size, shape, membrane potential, metabolic activity, and responsiveness to signals. These changes are largely due to highly controlled modifications in gene expression and are the study of epigenetics. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. Metabolic composition, however, gets dramatically altered where st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protoplasm
Protoplasm (; ) is the part of a cell that is surrounded by a plasma membrane. It is a mixture of small molecules such as ions, monosaccharides, amino acids, and macromolecules such as proteins, polysaccharides, lipids, etc. In some definitions, it is a general term for the cytoplasm (e.g., Mohl, 1846), but for others, it also includes the nucleoplasm (e.g., Strasburger, 1882). For Sharp (1921), "According to the older usage the extra-nuclear portion of the protoplast 'the entire cell, excluding the cell wall''was called "protoplasm," but the nucleus also is composed of protoplasm, or living substance in its broader sense. The current consensus is to avoid this ambiguity by employing Strasburger's (1882) terms cytoplasm Kölliker (1863), originally as synonym for protoplasm''and nucleoplasm van Beneden (1875), or karyoplasm, used by Walther Flemming">Flemming (1878)''">karyoplasm">'term coined by Edouard Van Beneden">van Beneden (1875), or karyoplasm, used by Walther Flemming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Growth
Primary growth in plants is growth that takes place from the tips of roots or shoots. It leads to lengthening of roots and stems and sets the stage for organ formation. It is distinguished from secondary growth that leads to widening. Plant growth takes place in well defined plant locations. Specifically, the cell division and differentiation needed for growth occurs in specialized structures called meristems. These consist of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells continue to divide until they differentiate and then lose the ability to divide. Thus, the meristems produce all the cells used for plant growth and function. At the tip of each stem and root, an apical meristem adds cells to their length, resulting in the elongation of both. Examples of primary growth are the rapid lengthening growth of seedlings after they emerge from the soil and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermis (botany)
The epidermis (from the Greek language, Greek ''ἐπιδερμίς'', meaning "over-skin") is a single layer of cells that covers the leaf, leaves, flowers, roots and Plant stem, stems of plants. It forms a boundary between the plant and the external environment. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients. The epidermis of most leaves shows Anatomical terms of location#Dorsal and ventral, dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. Woody stems and some other stem structures such as potato tubers produce a secondary covering called the periderm that replaces the epidermis as the protective covering. Description The epidermis is the outermost cell layer of the primary plant body. In some older works the cells of the leaf epidermis have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woody Plants
A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring. Characteristics Woody plants are usually trees, shrubs, or lianas. These are usually perennial plants whose stems and larger roots are reinforced with wood produced from secondary xylem. The main stem, larger branches, and roots of these plants are usually covered by a layer of bark. Wood is a structural tissue that allows woody plants to grow from above ground stems year after year, thus making some woody plants the largest and tallest terrestrial plants. Woody plants, like herbaceous perennials, typically have a dormant period of the year when growth does not take place. This occurs in temperate and continental due to freezing temperatures and lack of daylight during the winter months. Meanwhile, dormancy in subtropical an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Wilhelm Von Nägeli
Carl may refer to: *Carl, Georgia, city in USA *Carl, West Virginia, an unincorporated community *Carl (name), includes info about the name, variations of the name, and a list of people with the name *Carl², a TV series * "Carl", an episode of television series ''Aqua Teen Hunger Force'' * An informal nickname for a student or alum of Carleton College CARL may refer to: *Canadian Association of Research Libraries *Colorado Alliance of Research Libraries See also *Carle (other) *Charles *Carle, a surname *Karl (other) *Karle (other) Karle may refer to: Places * Karle (Svitavy District), a municipality and village in the Czech Republic * Karli, India, a town in Maharashtra, India ** Karla Caves, a complex of Buddhist cave shrines * Karle, Belgaum, a settlement in Belgaum ... {{disambig ja:カール zh:卡尔 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
