reduction

1. The restoration, by surgical or manipulative procedures, of a part to its normal anatomic relation. SYN: repositioning (2). 2. In chemistry, a reaction involving a gain of one or more electrons by a substance, such as when iron passes from the ferric (3+) to the ferrous (2+) state, or when hydrogen is added to the double bond of an organic compound, or when an aldehyde is converted to an alcohol. [L. reductio, fr. re-duco, pp. ductus, to lead back]

- r. of chromosomes the process during meiosis whereby one member of each homologous pair of chromosomes is distributed to a sperm or ovum; the diploid set of chromosomes (46 in humans) is thus reduced to the haploid set in each gamete; union of the sperm and ovum then restores the diploid or somatic number in the one-cell zygote.

- closed r. of fractures r. by manipulation of bone, without incision in the skin.

- r. en masse r. of hernial sac and contents, so that intestinal obstruction is still present.

- open r. of fractures r. by manipulation of bone, after surgical exposure of the site of the fracture.

- selective r. a technique for intrauterine termination of one or more fetuses while leaving one or more fetuses undisturbed, usually in pregnancies with fetal anomalies or with multiple gestations. SYN: selective termination.

- tuberosity r. the surgical excision of excessive fibrous or bony tissue in the area of the maxillary tuberosity prior to the construction of prosthetic appliances.

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re·duc·tion ri-'dək-shən n

1) the replacement or realignment of a body part in normal position or restoration of a bodily condition to normal

2) the process of reducing by chemical or electrochemical means

3) the psychological diminishment of emotion or needs through activity or adjustment

4) MEIOSIS specif production of the gametic chromosome number in the first meiotic division

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n.

(in surgery) the restoration of a displaced part of the body to its normal position by manipulation or operation. The fragments of a broken bone are reduced before a splint is applied; a dislocated joint is reduced to its normal seating; or a hernia is reduced when the displaced organ or tissue is returned to its usual anatomical site.

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re·duc·tion (re-dukґshən) [L. reductio] 1. the correction of a fracture, dislocation, or hernia. 2. in chemistry, the addition of hydrogen to a substance, or more generally, the gain of electrons.