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stem cells

(Encyclopedia)stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastu...

stem

(Encyclopedia)stem, supporting structure of a plant, serving also to conduct and to store food materials. The stems of herbaceous and of woody plants differ: those of herbaceous plants are usually green and pliant ...

glial cells

(Encyclopedia)glial cells: see brain.

brain stem

(Encyclopedia)brain stem, lower part of the brain, adjoining and structurally continuous with the spinal cord. The upper segment of the human brain stem, the pons, contains nerve fibers that connect the two halves ...

Gurdon, Sir John Bertrand

(Encyclopedia)Gurdon, Sir John Bertrand, 1933–, British biologist, Ph.D. Oxford, 1962. He has been a researcher at Cambridge since 1971. Gurdon was the joint recipient of the 2012 Nobel Prize in Physiology or Med...

Yamanaka, Shinya

(Encyclopedia)Yamanaka, Shinya, 1962–, Japanese physician and researcher, grad. Kobe Univ. (M.D., 1987), Osaka City Univ. (Ph.D., 1993). He was a professor at Osaka City Univ. (1996–99), the Nara Institute of S...

bark, in botany

(Encyclopedia)bark, outer covering of the stem of woody plants, composed of waterproof cork cells protecting a layer of food-conducting tissue—the phloem or inner bark (also called bast). As the woody stem increa...

pith

(Encyclopedia)pith, in botany, core of the stem of most plants. Pith is composed of large, loosely packed food-storage cells. As the stem grows older the pith usually dries out, and in some it disintegrates and the...

meristem

(Encyclopedia)meristem mĕrˈistĕmˌ [key], a specialized section of plant tissue characterized by cell division and growth. Much of the mature plant's growth is provided by meristems. Apical meristems found at th...

tissue

(Encyclopedia)tissue, in biology, aggregation of cells that are similar in form and function and the intercellular substances produced by them. The fundamental tissues in animals are epithelial, nerve, connective, ...