Structural characterization and origin of surface vesicles in monocytes: another membranous pathway from cytoplasm to cell surface.

The monocytes in acute monocytic leukemia (AML-M5b) were analyzed by scanning and transmission electron microscopy (SEM and TEM) to understand more fully their structure and origin. By SEM, monocytes exhibited localized expansions of the surface, some of which appeared to bud off as surface vesicles (SVs). Filopodial processes and pseudopodia were also present. TEM demonstrated that the SVs were composed of a double-membrane at the pole away from the cell body, and a single membrane nearer to the cell body. In the peripheral cytoplasm, intracellular vesicles (IVs) had the appearance of vacuoles and were enclosed by single membranes. Most SVs were characterized by a notch as a rER edge and an expanded head. Filopodial processes had the same thickness of 40 nm as the SV walls, which suggested a close developmental relationship between the two. Pseudopodia between SVs were irregular in size. Rod-like rER cisternae were prominent in the peripheral cytoplasm and some showed a close physical juxtaposition as to suggest a transition from rER to IVs to SVs. Ultrastructural cytochemistry demonstrated activity of 5'-nucleotidase over rER, SVs, filopodial processes and pseudopodia, and a patchy reaction over other areas of plasma membrane. Overall, the results indicated that rER transforms into SVs, filopodial processes and pseudopodia, as a way of integrating cytoplasmic membranes into the plasma membrane.

Malformation of the endoplasmic reticulum system evolving into giant inclusions and Auer bodies in acute promyelocytic leukemia: an ultrastructural study of 6 cases.

The endoplasmic reticulum（ER）is the largest membranous network serving as a region for protein, lipid and steroid synthesis, transport and storage. Detailed information about ER-cisternae, ER-tubules and rough endoplasmic reticulum (rER) is scarce in human blood cells. This study describes a series of giant inclusions and Auer bodies in promyeloblasts in six patients with acute promyelocytic leukemia (APL), by light microscopy, transmission electron microscopy (TEM) and cytochemical stains. TEM revealed that giant inclusions and pro-Auer bodies were associated with rER and surrounded by tubular structures composed of degenerated or redundant membrane in promyeloblasts, which corresponded with elements of the ER system. This paper reveals that in the promyeloblasts of APL, ER is the source of and transforms progressively into giant inclusions and Auer bodies.

Ultrastructural analysis of nucleated erythrocyte in patients with autoimmune hemolytic anemia (AIHA).

Autoimmune hemolytic anemia (AIHA) is a group of diseases characterized by immune-mediated lysis of mature red blood cells (RBCs). It is mainly classified into primary and secondary types based on etiology and mechanisms underlying autoantibody production. AIHA is diagnosed using morphological observation of bone marrow smears under a light microscope and monospecific direct antiglobulin test to detect hemolysis. Here, we retrospectively studied ultrastructural abnormalities of nucleated erythroid cells in bone marrows from 10 patients with AIHA using transmission electron microscopy. Our results revealed severe damage and injury to nucleated erythroid cells, including morphological irregularity, pyknosis, karyolysis, expansion of perinuclear cisternae and cytoplasmic lysis. These results indicate that aberrant immunity attacks not only mature RBCs but also nucleated erythroid cells, and ineffective hematopoiesis is partly involved in the pathogenesis of AIHA.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome: a case report.

A biopsy of gastrocnemius muscle from a patient with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome was studied histologically in semithin sections stained by hematoxylin-and-eosin (H&E) and toluidine blue, and ultrathin sections by transmission electron microscopy (TEM). H&E stain demonstrated typical ragged-red fibers (RRFs) and affected fibers in fascicles. Toluidine-blue stain showed an irregular meshwork in the center of RRFs. TEM demonstrated damaged myofibrils and variations in mitochondrial structure in RRFs and affected fibers. Dense mitochondria were compacted with cristae and pleomorphic electron-dense inclusions. Lucent mitochondria included paracrystalline inclusions with a parking lot appearance. At high magnification, the paracrystalline inclusions were composed of plates that paralleled and connected with mitochondrial cristae. These observations indicated that electron-dense granular and paracrystalline inclusions resulted from cristal degeneration and overlapping in mitochondria in MELAS syndrome.

Comparative analysis of full-length transcriptomes based on hybrid population reveals regulatory mechanisms of anthocyanin biosynthesis in sweet potato (Ipomoea batatas (L.) Lam).

BACKGROUND: Sweet potato (Ipomoea batatas (L.) Lam.) is a highly heterozygous autohexaploid crop with high yield and high anthocyanin content. Purple sweet potato is the main source of anthocyanins, and the mechanism of anthocyanin biosynthesis in storage roots has not been fully revealed. RESULTS: In order to reveal the mechanism of anthocyanin biosynthesis and identify new homologous genes involved in anthocyanin biosynthesis in the storage roots of sweet potato, we used Ningzishu 1 and Jizishu 2 as parents to construct a F1 hybrid population. Seven anthocyanin-containing lines and three anthocyanin-free lines were selected for full-length and second-generation transcriptome analyses. A total of 598,375 circular consensus sequencing reads were identified from full-length transcriptome sequencing. After analysis and correction of second-generation transcriptome data, 41,356 transcripts and 18,176 unigenes were obtained. Through a comparative analysis between anthocyanin-containing and anthocyanin-free groups 2329 unigenes were found to be significantly differentially expressed, of which 1235 were significantly up-regulated and 1094 were significantly down-regulated. GO enrichment analysis showed that the differentially expressed unigenes were significantly enriched in molecular function and biological process. KEGG enrichment analysis showed that the up-regulated unigenes were significantly enriched in the flavonoid biosynthesis and phenylpropanoid biosynthesis pathways, and the down-regulated unigenes were significantly enriched in the plant hormone signal transduction pathway. Weighted gene co-expression network analysis of differentially expressed unigenes revealed that anthocyanin biosynthesis genes were co-expressed with transcription factors such as MYB, bHLH and WRKY at the transcription level. CONCLUSIONS: Our study will shed light on the regulatory mechanism of anthocyanin biosynthesis in sweet potato storage roots at the transcriptome level.

Foam cell origination from degenerated vascular smooth muscle cells in atherosclerosis: An ultrastructural study on hyperlipidemic rabbits.

To clarify foam cell origination in atherosclerosis, a series of morphologic and ultrastructural alterations of vascular smooth muscle cells (VSMCs) and foam cells were studied by light and electron microscopy in atherosclerotic aortas from hyperlipidemic rabbits induced for 5 weeks. The study exhibited that VSMCs were severely degenerated and damaged, including irregular shapes, expanded mitochondria, aplenty lipid droplets, and disarranged myofilaments in cytoplasm in media adjacent to atheromatic bottoms. Most lipid laden cells shared interphase structures of VSMCs and foam cells, and some dissolved spindle cells contained lipid droplets, lipofuscin, and rod-like CCs in cytoplasm also. The result demonstrated that VSMCs were degenerated and transformed into foam cells in atherosclerosis, which was responsible for the accumulation of lipid and cholesterol crystals in atherosclerotic arteries.

One cell one niche: hematopoietic microenvironments constructed by bone marrow stromal cells with fibroblastic and histiocytic features.

Hematopoietic microenvironments have been extensively studied, especially focusing on regulation of hematopoietic stem cells (HSCs) in HSC niche following progress of molecular biology in resent years. Based on prior morphological achievements from 1970s, the characteristics of cellular compartments and bone marrow stromal cells (BMSCs) were studied ultrastructurally in human and mice bone marrow in the present study. The samples, human bone marrow granules, were collected from bone marrow aspirations (BMAs) of 20 patients with hematocytopenia and isolated BMSCs were found undesignedly in nucleated cells of BMAs of the patients. Femoral bone marrow samples were collected from 6-week-old three sacrificed mice. Detailed images illustrated maturing hematopoietic cells harbored individually in honeycomb-like microenvironment constituted by BMSCs that shared of fibroblastic and histiocytic characteristics in hematopoietic microenvironments of human and mice bone marrow.

Systematic alteration of apoptosis: a review with ultrastructural observations on leukemia cells in vivo.

The ultrastructural characteristics of apoptosis have been described microscopically for four decades. Alterations of nuclei, apoptotic bodies, cytoplasm, and some organelles have been illustrated and investigated during apoptosis. The successive changes of cellular components corresponding with differentiation of apoptotic cells are illustrated in the present review, based on ultrastructural observation of leukemia cells of patients in our routine clinic work by transmission electron microscopy. Most electron micrographs demonstrated that membranous components of nuclear envelop, rough endoplasmic reticulum and Golgi apparatus, and mitochondria were degenerated step by step during apoptosis. The successive images suggested that the endoplasmic reticulum and Golgi apparatus were transferred to cell surface from cytoplasm and participated in formation of apoptotic bodies in apoptosis, although relevant clinical data and more experimental evidence were needed for restraining of leukemia cases from diagnostic work randomly in recent decades.

A novel anemia associated with membranous cytoplasm degeneration in 16 patients: an ultrastructural study.

Sixteen patients with mild anemia and hemolysis were difficult to be classified into any known category based on laboratory examinations and light microscopy. To make a definite diagnosis and investigate the pathomechanism, ultrastructural study was performed on erythroid cells from 16 patients. Transmission electron microscopy demonstrated a series of alterations of cytoplasm, including cytoplasm sequestration, membranous transformation, and degeneration in erythroblasts and reticulocytes at different stages. The affected erythroblasts were usually complicated with chromatin condensation, karyorrhexis, nuclear membrane lysis, and megaloblastic changes. The reticulocytes with the cytoplasm alterations had a huge size from 10 um to 15 um in diameter. The membranous cytoplasm degeneration revealed a unique pathomechanism of dyserythropoiesis and ineffective erythropoiesis in 16 patients with anemia, and suggested a novel anemia category though more details remained to be investigated.

Platelet production of megakaryocyte: A review with original observations on human in vivo cells and bone marrow.

Megakaryocytes (MKs) build characteristic structures to produce platelets in a series of steps. Although mechanisms of demarcation membrane system (DMS) and open canalicular system transformation have been proposed based on experimental studies in recent decades, the related evidence is lacking in human cells in vivo. The present review describes and discusses the development of MKs, transformation of DMS, and the release and maturation of proplatelets based on our observation of human MKs in vivo and bone marrow biopsy by light microscope and transmission electron microscope. Four stages were subdivided from megakaryoblasts to matured cells; presumption of DMS transformation from endoplasmic reticulum and Golgi apparatus were evidenced in contrast to another presumption of DMS transformation from plasma membrane in this review. Effectors of interaction between hematopoietic cells, the sucking and shearing force of sinus blood flow on movement of MKs, and release of proplatelets were emphasized. Additionally, the mechanism of secondary splitting of proplatelets in circulation was demonstrated ultrastructurally. These findings and conceptions might significantly promote our understanding of the mechanism of platelet production in human in vivo cells.

Histiocytic differentiation in acute monocytic leukemia.

Myeloid histocytes of dendritic cells (DCs), Langerhans cells (LCs), and macrophages in varied tissues, as leukemic blasts in acute monoblastic and monocytic leukemia (AML-M5a and M5b), are derived from monocyte progenitors in bone marrow. Based on DC induction from hematopoietic stem cells, myeloid progenitors, and monocytes, and occasional expressions of histocyte-related antigens (HRAs) in M5, we presume some M5 cases share histiocytic phenotypes originally. To clarify the conception, 93 M5 cases were tested with antibodies for HRAs, CD1a, CD163, S100, fascin, and langerin by immunostaining, and their morphologic characteristics were studied by light and transmission electron microscopy. The study revealed that 23 M5 cases were positive for two or more kinds of HRAs and shared a serial of histocytic immunophenotype and morphologic features, which were closely associated with M5b subtype and expression of CD14 in M5.

p32 is a novel target for viral protein ICP34.5 of herpes simplex virus type 1 and facilitates viral nuclear egress.

As a large double-stranded DNA virus, herpes simplex virus type 1 (HSV-1) assembles capsids in the nucleus where the viral particles exit by budding through the inner nuclear membrane. Although a number of viral and host proteins are involved, the machinery of viral egress is not well understood. In a search for host interacting proteins of ICP34.5, which is a virulence factor of HSV-1, we identified a cellular protein, p32 (gC1qR/HABP1), by mass spectrophotometer analysis. When expressed, ICP34.5 associated with p32 in mammalian cells. Upon HSV-1 infection, p32 was recruited to the inner nuclear membrane by ICP34.5, which paralleled the phosphorylation and rearrangement of nuclear lamina. Knockdown of p32 in HSV-1-infected cells significantly reduced the production of cell-free viruses, suggesting that p32 is a mediator of HSV-1 nuclear egress. These observations suggest that the interaction between HSV-1 ICP34.5 and p32 leads to the disintegration of nuclear lamina and facilitates the nuclear egress of HSV-1 particles.

On the maturation of megakaryocytes: a review with original observations on human in vivo cells emphasizing morphology and ultrastructure.

Megakaryocytes engage in the synthesis of a variety of molecular and macromolecular constituents to build-up characteristic megakaryocyte structure and form proplatelets in a series of cells from megakaryocyte precursors to the fully matured cell. The process is illustrated in this review by light microscope morphology and transmission electron microscopy, which emphasizes new findings in human in vivo megakaryocytes, thereby making a contrast with the abundant literature on megakaryocytes from experimental animal and human in vitro material. Four stages are identified and described, based on the development of characteristic structures including α-granules, dense granules (dense-core granules), the demarcation membrane system (DMS), and proplatelets. The mechanism of DMS development is discussed, in terms of hypotheses suggesting origin from the plasma membrane, and contributions of membrane from the Golgi apparatus and endoplasmic reticulum. The formation of the marginal zone is also discussed, which is suggested to result from a circumscription of the peripheral organelle-free cytoplasmic fringe by peripheral circular cytoskeletal elements such as cytoplasmic actin and microtubules.

Congenital dyserythropoietic anemia in China: a case report from two families and a review.

Congenital dyserythropoietic anemias (CDAs) are a group of hereditary disorders characterized by ineffective erythropoiesis and distinct morphological abnormalities of erythroblasts in the bone marrow. Most cases of CDA, caused by a wide spectrum of mutations, have been reported from Europe and Mediterranean countries, while a few cases have been described in China. Here, we present three cases of CDA, one from one family and two from a second unrelated family, with typical morphologic features and clinical presentations. Sequence analysis of CDA-related genes revealed that the proband with CDA Ι in the first family was a compound heterozygote of CDAN1 with mutation IVS-12+2T>C and c. 3389C>T, while both probands with CDA ΙΙ in the second family were a homozygote of the SEC23B gene with mutation c.938G>A (R313H). This study suggests that more patients with CDA, sharing a phenotype and genetic background like those of European and Mediterranean origin, remain to be diagnosed and reported in China.

Activation of monocyte-derived cells in the bone marrow of myelodysplastic syndrome.

OBJECT: To study the relationship between monocyte/histiocyte activation and myelodysplastic syndrome (MDS). METHODS: Analyzing ultrastructure and myeloperoxidase reaction of nucleated cells in bone marrow from 59 cases of MDS by transmission electron microscopy. Four groups of MDS were subdivided on the basis of their content of activated inflammatory cells - morbid hematopoiesis with minimal inflammatory cell activation (MH-MICA); MDS with monocytic system activation (MSA); MDS with lymphocyte activation (LCA); and MDS with granulocyte activation (GCA). RESULTS: About 20, 22, 7, and 10 cases were classified as MH-MICA (34%), MSA (37%), LCA (12%), and GCA sub-types (17%), respectively. About 3, 5, 0, and 3 cases from MH-MICA, MSA, LCA, and GCA, respectively, underwent leukemic transformation within 2 years. CONCLUSION: The findings suggest that activation of inflammatory cells in bone marrow is an important feature of MDS, and that monocytes/histocytes are perhaps the most prominent cellular participants in the pathogenesis of MDS.

Morphologic characteristics of blastic plasmacytoid dendritic cell neoplasm: a case report.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare aggressive lymphoma derived from plasmacytoid dendritic cells or precursor dendritic cells. Despite some 240 reported cases, its morphology and especially ultrastructure has not been satisfactorily studied. A case is reported of a 13 year old boy, who, despite chemotherapy, died within a 12-month period. The electron microscopy findings - microvillous processes, nuclei with slight irregularities, a moderate amount of heterochromatin, and rough endoplasmic reticulum in the form of long, narrow profiles, often in parallel arrangements - taken together, serve to distinguish BPDCN from other neoplastic cells, such as monocytes, plasma cells and the cells of chronic lymphocyte leukemia.

Analysis of monocyte and histiocytic cell populations in bone marrow of patients with confirmed and suspected cases of reactive histocytosis.

OBJECTIVE: To describe characteristics of monocytes and histiocytes in the bone marrow of patients with a confirmed and suspected diagnosis of reactive histiocytosis. METHODS: 14 patients with a confident diagnosis of reactive histiocytosis or with a suspected diagnosis were inpatients at the Tianjin Blood Diseases Hospital between 2008 and 2012. Nucleated cells from bone marrow were observed by light microscopy - morphologically and immunohistochemically for histiocyte antigens - and ultrastructurally by transmission electron microscopy. RESULTS: Monocytes, atypical histiocytes, macrophages, hemophagocytes, reticular cells and dendritic cells were significantly increased in 9, 9, 5, 3, 3 and 2, respectively, of the 14 cases. Atypical histiocytes expressed some morphological characteristics of promonocytes. CONCLUSION: Monocytes, atypical histiocytes, macrophages, hemophagocytes, reticular cells and dendritic cells were increased in different relative degrees in patients with bone marrow reactive histiocytosis or suspected reactive histiocytosis. The increase in numbers of monocytes, atypical histiocytes and macrophages was a particularly significant feature. It is argued that atypical histiocytes with immature monocyte features might be precursors of hemophagocytes, reticular cells or dendritic cells.

Ultrastructural characteristics of erythroid cells in congenital dyserythropoietic anemia type II, with a focus on peripheral cisternae and double membranes.

Peripheral cisternae and double membranes (PCDMs) in erythroid cells are a landmark of type II congenital dyserythropoietic anemia (CDA). To gain further insights into the mechanism of dyserythropoiesis, erythroblasts and erythrocytes in bone marrow were studied in 22 Chinese patients with CDA Ⅱ by transmission electron microscopy. The study demonstrated an increase in all patients in erythroblasts with PCDMs with development from pro-erythroblast to red blood cells. PCDMs often connected with cisternae of endoplasmic reticulum (ER) and the perinuclear space, and were accompanied by karyopyknosis, karyolysis and disruption in polychromatic and orthochromatic erythroblasts. The results suggest that PCDMs are transformed from ER during erythropoiesis and participate in the dissolution and deletion of late erythroid cells in patients with CDA II.

Development of Auer bodies from giant inclusions associated with rough endoplasmic reticulum in acute promyelocytic leukemia.

Giant inclusions and Auer bodies in promyeloblasts were investigated in a study which included transmission electron microscopy (TEM) for morphology and ultrastructural cytochemistry for myeloperoxidase in 10 patients with acute promyelocytic leukemia (APL). Ultrastructural cytochemistry demonstrated positive myeloperoxidase reactivity in giant inclusions, expanded rER cisternae, Auer bodies and primary granules. TEM revealed that giant inclusions were adorned by degenerated rER membrane, some of them sharing features with Auer bodies. We hypothesize a novel origin for Auer body development in promyeloblasts of APL, namely that they originate from peroxidase-positive and expanded rER cisternae, and that primary granules were directly released from these expanded rER elements, bypassing the Golgi apparatus.