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Protococcus is a genus of single-celled Algae. The British species Protococcus viridis forms a yellowish-green stratum on trees, damp walls and shallow pools.
 Research Protococcus
The epidermis (surface of the skin) consists of dead cells, which are rubbed off as a person moves and goes about their business. This layer of dead cells is often refered to as 'false' skin. The
epidermis consists of four layers: the stratum basale, the stratum spinosum, the stratum granulosum, and the stratum corneum.
Research Epidermis
The renal capsule is the membranous covering of the kidney. It directly covers the renal cortex, which forms the outer stratum of the kidney.
Research Renal Capsule
The sebaceous glands lie just below the skin adjacent to the hair follicles and connected by a short duct. They secretes sebum into the hair follicles, providing a lubricant for the hair and skin. Sebum is a semifluid substance composed of waxes, fatty acids, cholesterol, and debris from skin cells. By coating the hair and the dead keratin cells of the stratum corneum, sebum sequesters moisture, keeping hair glossy and skin pliable. Sebum is important for many other reasons. It contains a precursor to vitamin D that produces the mature vitamin when struck by the ultraviolet rays of the sun. It also kills certain forms of harmful bacteria.
Research Sebaceous glands
The stratum basale is the deepest layer of the epidermis, consisting of a single row of columnar or cuboidal cells. The epidermal cells originate from this layer and new cells are continually being produced. Some of these cells make the protein keratin, which toughens them. Others produce melanin, the substance that gives skin colour. As the cells in this layer increase in number, they are pushed outward and become part of the stratum granulosum.
Research Stratum Basale
The stratum corneum is the outer layer of the epidermis. It is composed of flat, dead cells which have lost their nuclei. It is constantly being sloughed off as dandruff. These cells are rubbed off as you move, wear clothes, and wash. Keratin, a horny protein found in hair and fingernails, is also found in the cells of the stratum corneum and prevents evaporation. It also helps to ward off injury because of its toughness.
Research Stratum Corneum
The stratum granulosum is the thin layer of epidermis, composed of only a few layers of cells just above the stratum spinosum. The cells of the stratum granulosum fill with keratin and die as they continue upward to reach the top layer, the stratum corneum. The entire process takes about a month and the cells are worn away with friction.
Research Stratum Granulosum
The stratum spinosum is the middle layer of the epidermis between the stratum basale and the stratum granulosum.
Research Stratum Spinosum
In geology, the term bed describes a layer or seam, or a horizontal stratum of one formation between layers of others, for example a bed of coal, iron, etc.
Research Bed
In geology a dip is the inclination or angle at which strata slope or dip downwards into the earth. The degree of inclination or amount of the dip, which is easily measured by a special instrument, is determined by the angle which a line drawn perpendicular to the direction of the stratum makes with the horizon. The line in which such strata cut the surface is called the strike, and is always at right angles to the dip.
Research Dip
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The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
©1993 - 2009 The Probert Encyclopaedia
Southampton, United Kingdom
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Abbreviations
