1) Involucre 
Involucrum is a layer of new bone growth outside existing bone seen in pyogenic osteomyelitis. It results from the stripping off of the periosteum by the accumulation of pus within the bone, and new bone growing from the periosteum. It can be seen radiographically (e.g. with x-rays), but is extremely rare in developed countries as osteomyelitis is...
• (n.) See Involucre. • (n.) A sheath which surrounds the base of the lasso cells in the Siphonophora.
(in″vo-loo´krәm) Latin word meaning a covering or sheath, as of a sequestrum.
In`vo·lu'crum noun ; plural Latin Involucra , English Involucrums . [ Latin See Involucre .] 1. (Botany) See Involucre . 2. (Zoology) A sheath which surrounds the base of the lasso cells in the Siphonophora. 
Type: Term Pronunciation: in′vō-lū′krŭm, -loo′kră Definitions: 1. An enveloping membrane, a sheath or sac. 2. The sheath of new bone that forms around a sequestrum. Synonyms: involucre
A covering or sheath, such as contains the sequestrum of a necrosed bone; localized overgrowth or hypertrophy of bone in response to infection
involucre.