Akademik

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1. Defective development or congenital absence of an organ or tissue. 2. In hematology, incomplete, retarded, or defective development, or cessation of the usual regenerative process. [G. a- priv. + plasis, a molding]

- congenital a. of thymus SYN: DiGeorge syndrome.

- a. cutis congenita [MIM*107600, *207700, *207730] congenital absence or deficiency of a localized area of skin, with the base of the defect covered by a thin translucent membrane; most often a single area near the vertex of the scalp, but may occur in other areas; underlying structures may also be affected; autosomal inheritance, either dominant or recessive.

- germinal a. SYN: seminiferous tubule dysgenesis.

- gonadal a. congenital absence of essentially all gonadal tissue; the external genitalia and genital ducts are female, but if interstitial cells of Leydig are present, the external genitalia are commonly ambiguous and the genital ducts are female. SEE ALSO: gonadal dysgenesis, gonadal agenesis. Cf.:Klinefelter syndrome, Turner syndrome.

- pure red cell a. a transitory arrest of red blood cell production which may occur in the course of a hemolytic anemia, often preceded by infection, or as a complication of certain drugs; if the arrest persists, severe anemia may result. SEE ALSO: congenital hypoplastic anemia.

apla·sia (')ā-'plā-zh(ē)ə, ə- n incomplete or faulty development of an organ or part

total or partial failure of development of an organ or tissue. See also agenesis.

• aplastic adj.