a Related Biological Terms

In vertebrates, the limb bones and the bones that support them.

A thin tube extending from the cecum in the human digestive system.

Generally refers to a software package with a specific purpose.

In the eye, a nutritive, watery fluid between the cornea and the lens that focuses incoming light rays and maintains the shape of the eyeball.

A solution in which water is the solvent.

a water-bearing layer of soil, sand, gravel, or rock that will yield usable quantities of water to a well. An aquifer, in hydrology, is a rock layer that contains water and releases it in appreciable amounts. The rock contains water-filled pore spaces, and when the spaces are connected, the water can flow through the rock matrix. An aquifer also may be called a water-bearing stratum, lens, or zone. Wells can be drilled into many aquifers, and they are one of the most important sources of fresh water on Earth. The Types of Aquifer (1)A confined aquifer is a water-bearing stratum that is confined or overlain by a rock layer that does not transmit water in any appreciable amount, or that is impermeable. (2)A groundwater aquifer is said to be unconfined when its upper surface (water table) is open to the atmosphere through a permeable material. (3) Unlike a confined aquifer, the water table in an unconfined aquifer system has no overlying impervious rock layer to separate it from the atmosphere.

Arachidonic acid (AA) is a polyunsaturated fatty acid present in the phospholipids (especially phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositides) of membranes of the body's cells, and is abundant in the brain, muscles, and liver. Arachidonic acid is an essential fatty acid and a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes Bosetti. Arachidonic acid is synthesized from γ-linolenic acid derived from linoleic acid, an essential fatty acid, by the enzyme Δ6-desaturase. Once formed, arachidonic acid can be converted to any of the eicosanoids. Arachidonic acid is the quantitatively most important precursor in PG biosynthesis. Arachidonic acid liberated from membrane phospholipids by the actions of phospholipase A2 (PLA2) is transformed to the unstable endoperoxide PGH2 by the COX enzyme.

Multicellular structures in plants where female gametes form.

cavity formed during gastrulation by invagination of the vegetal plate Cells (in sea urchin) or involution of Cells at the blastoporal lip (in amphibians); it will become the interior of the primitive gut.

a somatic cell of sponge that can differentiate into all three other cell types of the organism.