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Related to pore: pore over, Pore pressure, skin pore


1. Anatomy Zoology any small opening in the skin or outer surface of an animal
2. Botany any small aperture, esp that of a stoma through which water vapour and gases pass
3. any other small hole, such as a space in a rock, soil, etc.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in plant anatomy, a thin, microscopic area in the primary cell membrane. Pores, which are more commonly called pits, usually appear in pit fields, intertwined with plasmodesmata of cytoplasm. They are formed during the uneven secondary thickening of the cell membrane. Pores may appear in the membranes of adjacent cells (pit-pairs). A distinction is made between simple pits, which are found in parenchyma tissues and in fibers, and bordered pits, which form chiefly in the water-conducting elements of woody tissue. In the tracheids of conifers, the membrane of bordered pits of adjacent cells has a thickening in the center called a torus, which can function as a valve. Pores play an important role in the vital activity of cells and in the conduction of substances to all the tissues. Pores are also present in the cell membranes of lower plants. Sometimes the conducting elements of vessels in higher plants develop contiguous openings in the membranes of adjacent cells (at the site of the pores) called perforations.


The pores of animals included the openings of the efferent ducts of the sweat glands on the surface of the epidermis (sweat pores) and the openings of the canals by which the taste receptors communicate with the surface of the epithelium of the oral cavity (taste pores).

In karyology, pores are round spots filled with a solid substance in the membrane of the cell nucleus. They are circumscribed by the fused surface of the internal and external nuclear membrane, which forms a small ring containing eight granules joined together by thin fibrils. The substance filling the pore sometimes presses deep into the karyoplasm in the form of a cylinder and protrudes slightly into the cytoplasm surrounding the nucleus, forming a pore complex with the ring. A pore is 200–1,000 A in diameter. Pores occupy 5 to 10 percent of the entire nuclear membrane surface. Owing to the nature of permeability, pores play an important role in the transport of macromolecular substances from the nucleus to the cytoplasm and back.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A very small, dark area on the sun formed by the separation of adjacent flocculi.
Any minute opening by which matter passes through a wall or membrane.
An opening or channelway in rock or soil.
A minute cavity in a powder compact, metal casting, or electroplated coating.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Figure 5 shows the dependence of electrical conductivity and crystallinity of the PPy:PSS composites on the size of the micro-pores in the filter paper used for synthesis and Table 2 shows the relationship between conductivity and pore size.
where r is the pore radius, D is the pore fractal dimension, and c is a constant.
where [d.sub.10] is the diameter of the corresponding pore image block when the cumulative area is 10%.
Figure 5 shows the relation between the cooling speed, lamellar spacing, and spherical pore spacing of the two kinds of ceramic pores.
The present work is aimed at investigating the nanoscale pore structure characteristics as well as porosity and permeability of the mudrock and fine-grained sandstone which are the most typical rock types in coal reservoirs of China by using combined methods of FIB-SEM, MIP, and NMR.
The main output of the test was excess pore water pressure time history.
Figure 4 shows the pore radii as function of density.
Cross-sectional information on the pore microstructure characteristics and element distribution rule was analyzed in detail.
Excessive production of oil in people with oily skin causes the pores to get clogged resulting in constant stretching of their walls and consequent enlargement.
The Geolog log-based pore pressure prediction module offers tools to predict pore and fracture pressure profiles in wells based on logging data.