Absence or closure of a natural passage or channel of the body; imperforation.

Congenital absence or occlusion of an orifice or tubular organ.

The absence or closure of the external or middle ear.

An absent portion of an organ. Intestinal atresia (ileal or jejunal atresia) refers to a missing portion of small bowel, a known complication of gastroschisis. If present, this will require an operation, to reconnect the two ends of bowel

an abnormal condition in which a normal opening or tube in the body (as the urethra) is closed or absent

a gap in the bowel causing a complete blockage (obstruction) of the bowel

(Greek, = without + tresis = perforation) closing of a cavity or opening. (More? see atretic follicle

Degeneration and resorption of a follicle before it reaches maturity and ruptures.

The closing of a cavity, or its incomplete development; refers to the degeneration of developing ovarian follicles.

Blocked, destroyed, missing.

blocked or missing

The failure of a bodily structure to develop and the tissue to fully close as it normally would. Usually present and open at birth.