natrijum-kalijum pumpa

The middle layer of cells in embryonic development; gives rise to muscles, bones, and structures associated with reproduction. The middle embryonic tissue layer. Cells and ...

melanin

生物学; 細胞生物学

A pigment that gives the skin color and protects the underlying layers against damage by ultraviolet light; produced by melanocytes in the inner layer of the epidermis.

mejoza

生物学; 細胞生物学

Cell division in which the chromosomes replicate, followed by two nuclear divisions. Each of the resulting gametes (in animals, spores in plants) receives a haploid set of ...

megaspore

生物学; 細胞生物学

Four haploid cells produced by meiosis in the ovule of a þower. Usually, three of these cells degenerate, with the remaining cell becoming the female gametophyte phase of the ...

moždina

生物学; 細胞生物学

1. A term referring to the central portion of certain organs; e. G. , the medulla oblongata of the brain and the adrenal medulla, which synthesizes epinephrine and norepinephrine. ...

makroevolucija

生物学; 細胞生物学

The combination of events associated with the origin, diversification, extinction, and interactions of organisms which produced the species that currently inhabit the Earth. Large ...