PARALLEL TUBULAR GRANULES IN HUMAN IMMATURE NEUTROPHILS - AN ELECTRON-MICROSCOPIC STUDY

Unique rounded granules consisting of clustered parallel tubules, 29-3 1 nm in diameter, with occasional, flocculent or amorphous electron-de nse material (parallel tubular granules, PTGs) were found in immature neutrophils in the bone marrow in a case of chronic neutrophilic leuke mia (CNL). PTGs were positive for electron microscopic myeloperoxidase . Since no structures similar to PTGs have been documented, we investi gated the bone marrow of 65 adult patients with hematologic diseases, and 7 adult patients with miscellaneous non-hematologic diseases, by e lectron microscopy. The results showed that no PTGs were found in any cases other than the original CNL case. These findings suggest that PT Gs are rare granules representing certain primary granules. In additio n, the presence of PTGs might be helpful in diagnosing CNL.