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sperm

(Encyclopedia)sperm or spermatozoon spûrˌmətəzōˈən, –zōˈŏn [key], in biology, the male gamete (sex cell), corresponding to the female ovum in organisms that reproduce sexually. In higher animals the spe...

mesoderm

(Encyclopedia)mesoderm, in biology, middle layer of tissue formed in the gastrula stage of the developing embryo. At the end of the blastula stage, cells of the embryo are arranged in the form of a hollow ball. Con...

aging

(Encyclopedia)aging, in biology, cumulative changes in an organism, organ, tissue, or cell leading to a decrease in functional capacity. In humans, aging is associated with degenerative changes in the skin, bones, ...

botany

(Encyclopedia)botany, science devoted to the study of plants. Botany, microbiology, and zoology together compose the science of biology. Humanity's earliest concern with plants was with their practical uses, i.e., ...

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, ...

mutation

(Encyclopedia)mutation, in biology, a sudden, random change in a gene, or unit of hereditary material, that can alter an inheritable characteristic. Most mutations are not beneficial, since any change in the delica...

Hershey, Alfred Day

(Encyclopedia)Hershey, Alfred Day, 1908–1997, American microbiologist, b. Owosso, Mich., Ph.D., Michigan State College (now Michigan State Univ.), 1934. Hershey was a professor at the Washington Univ. School of M...

anatomy

(Encyclopedia)anatomy ənătˈəmē [key], branch of biology concerned with the study of body structure of various organisms, including humans. Comparative anatomy is concerned with the structural differences of pl...

In

(Encyclopedia)In, symbol for the element indium. ...

antiviral drug

(Encyclopedia)antiviral drug, any of several drugs used to treat viral infections. The drugs act by interfering with a virus's ability to enter a host cell and replicate itself with the host cell's DNA. Some drugs ...