Development of the granule population in heterophil granulocytes from rat bone marrow

Ultrastructural study of periodic lamellar granules in human neutrophils

Granules consisting of periodically arranged membranous lamellae and amorphous electron-opaque material, i.e., periodic lamellar granules, are present in human neutrophils. To date, no extensive ultrastructural studies have been carried out on these granules because of their infrequent presence in neutrophils. The bone marrow of 18 cases of chronic myeloproliferative disorders, including one case of chronic neutrophilic leukemia in which periodic lamellar granules were frequently seen in neutrophils, was investigated by electron microscopy. Periodic lamellar granules were seen in neutrophils in 12 of the 18 cases at varying frequencies. They were preferentially seen in immature neutrophils. The transverse profiles of these granules revealed concentric complete/incomplete rings or periodic parallel straight lines, i.e., various patterns of lamellar arrangement were present. Periodic lamellar granules were positive for myeloperoxidase and lysozyme at the electron-microscopic level. These results suggest that these granules represent a primary neutrophil granule subtype. However, their functional and pathologic significance remains unknown.

Ultrastructure of fibrillar granules in human neutrophils

Fibrillar granules (FGs) represent neutrophilic primary granules containing clustered filaments. We investigated neutrophils in the bone marrow obtained from 17 patients with chronic myeloproliferative disorders (CMPD) by electron microscopy. FG-positive neutrophils were seen in 15 of the 17 CMPDs with varying frequencies. The diameter of FG-filaments was 7-8 nm, showing that they corresponded to neither intermediate filaments nor actin filaments.

Parallel tubular granules in human immature neutrophils--an electron microscopic study

Unique rounded granules consisting of clustered parallel tubules, 29-31 nm in diameter, with occasional, flocculent or amorphous electron-dense material (parallel tubular granules, PTGs) were found in immature neutrophils in the bone marrow in a case of chronic neutrophilic leukemia (CNL). PTGs were positive for electron microscopic myeloperoxidase. Since no structures similar to PTGs have been documented, we investigated the bone marrow of 65 adult patients with hematologic diseases, and 7 adult patients with miscellaneous non-hematologic diseases, by electron microscopy. The results showed that no PTGs were found in any cases other than the original CNL case. These findings suggest that PTGs are rare granules representing certain primary granules. In addition, the presence of PTGs might be helpful in diagnosing CNL.

Effect of acute lead intoxication on the ultrastructure of neutrophils in the peripheral blood of the rat

The influence of lead acetate on the ultrastructure of peripheral neutrophils was investigated in adult male rats. It was found that a single intraperitoneal administration of lead at dose 150 mg Pb/kg b.w. led to ultrastructural changes in the neutrophils at 3 and 6 h post injection. At the time of testing the exposed population had a mean (+/- SD) blood lead concentration from 206.2 +/- 24.8 micrograms/100 ml to 75.2 +/- 9.9 micrograms/100 ml compared with a mean value of 4.0 +/- 0.7 micrograms/100 ml for the control groups. The ultrastructural alterations such as irregular nuclei with deep invaginations, plasma membrane pockets, the presence of vacuoles with a heterogeneous material and an increasing amount of RER cisternae, were most clearly expressed 6 h after lead administration. In addition there appeared sometimes nuclear pockets, and a prominent crystalline inclusion placed in the cytoplasmic matrix of some neutrophils. No differences in the mitochondrial morphology and cytoplasmic granule pattern between exposed and control rats were observed.

Granule formation and polarity of the Golgi apparatus in neutrophil granulocytes of the rat

The formation of granules in neutrophil (heterophil) progenitor cells was examined with the electron microscope in sections of rat bone marrow fixed in 2% glutaraldehyde and postfixed with reduced osmium (Karnovsky: Proceedings of the 11th Meeting, American Society of Cell Biologists, Abstr. 284, p. 146, 1971). The cells were also osmicated in 2% osmium tetroxide for 36 hours at 37 degrees C to outline the osmiophilic element usually observed on the cis-face of the stacks of saccules of the Golgi apparatus of various cell types. In myeloblasts, which do not produce granules, the cis-osmiophilic element (CE) was found on the concave face of the C-shaped Golgi stacks. In promyelocytes the CE was present on the convex aspect of the C-shaped stacks, while the primary (azurophilic) granules formed in relation to elements on the concave aspects of the stacks. In myelocytes, the situation was reversed: the CE was found on the concave face of the Golgi stacks, while the secondary (specific) granules were seen forming in relation to elements on the convex aspect of the stacks. Finally, in metamyelocytes and mature neutrophils in which no granule formation took place, the appearance on Golgi stacks varied: they were either flat or C-shaped. The CE was indiscriminately found on one face or the other of the flat Golgi stacks of metamyetocytes and on the convex or concave faces of the C-shaped Golgi stacks of mature neutrophils. Using the cis-osmiophilic-element as a marker of the cis-face of the stacked Golgi elements, it thus appeared that despite marked changes in the configuration and orientation of the stacks of the cis-trans polarity of the stacked elements was maintained throughout granulopoiesis. In addition the primary and secondary granules that appeared sequentially in promyelocytes and myelocytes were both seen to form in relation to trans-elements of the Golgi apparatus.

Ultrastructural localization of peroxidase activity in developing neutrophil granulocytes from human bone marrow

Developing neutrophil granulocytes of normal human bone marrow were investigated with the diaminobenzidine technique to determine the ultrastructural localization of peroxidase activity. Neutrophil granulocytes have three types of granule: nucleated, azurophil, and specific granules. These granules are produced consecutively during the eomyelocyte stage, the promyelocyte stage, and the myelocyte stage, respectively. The organelles involved in the production of granules, i.e., the nuclear envelope, rough endoplasmic reticulum, and Golgi apparatus, are peroxidase positive during the eomyelocyte and promyelocyte stages and peroxidase negative thereafter. This pattern differs for the granules themselves: nucleated granules are negative in the eomyelocyte and become positive in the promyelocyte. Azurophil granules become positive in the promyelocyte. Specific granules are negative. Our observations highly suggest that small Golgi-derived peroxidase-positive vesicles are involved in the maturation of both nucleated granules and azurophil granules.

Development of the granule population in neutrophil granulocytes from human bone marrow

Bone marrow from hematologically healthy adults was exposed to a number of fixation procedures for investigation of the heterogeneity of the granule population in neutrophil granulocytes at the ultrastructural level. Four main cell stages were distinguished: early promyelocyte, late promyelocyte, myelocyte, and mature neutrophil granulocyte and described separately; metamyelocytes and band-form or stab cells are described together. The characteristic changes in the cytoplasm during myelopoiesis were analysed quantitatively. Special attention was given to the development of the granule population. Three types of granule arise in successive cell stages: granules which develop a sub-structure in the matrix (nucleated granules) are formed in early promyelocytes, granules with a homogeneous electron-dense matrix (azurophil granules) in late promyelocytes, and granules with a less electron-dense matrix (specific granules) in myelocytes. The three types of granule remain present during myelopoiesis. The best results in distinguishing the granule types were obtained by prefixation either in 0.1% glutaraldehyde or in 1.5% glutaraldehyde followed by washing in phosphate-buffered Ringer solution to which aminotriazole had been added. Granule counts revealed for the mature neutrophil a total number of granules of about 220 per ultrathin section. This population of granules is composed of about 12% nucleated, 11% azurophil, and 77% specific granules. When our previous findings are taken into account, the existence of three successively formed and morphologically distinguishable types of granule in heterophil (neutrophil) granulocytes has been demonstrated for three mammalian species: the guinea pig, the rat, and man. A separate term for the early promyelocyte stage is proposed: eomyelocyte.