Aggregates Of Rough Endoplasmic Reticulum Research Articles

Ultrastructure of spermatiogenesis in the red alga Osmundea spectabilis var. spectabilis (Rhodomelaceae, Ceramiales, Rhodophyta)

Spermatiogenesis in Osmundea spectabilis var. spectabilis (= Laurencia spectabilis var. spectabilis) begins with the differentiation of the epidermal cells within the conceptacle. These cells divide to form filaments that develop toward the centre of the pit. Spermatangial mother cells originate from the cells of the filaments and produce several spermatangia. All young spermatia have some chloroplasts and are surrounded by a spermatangial wall. As the spermatia mature, rough endoplasmic reticulum aggregates and the formation of spermatial vesicles containing granular material commences. Subsequently, spermatial vesicles enlarge by contribution of dictyosome vesicles containing fibrillar material. Spermatia develop a two-layered wall and can be released at any stage of differentiation. Finally, the spermatial vesicles discharge their contents, forming an extracellular, confluent, mucilaginous matrix that surrounds the released mature spermatia. Bacteria cannot enter the spermatia since they are well protected by this matrix. Mature released spermatia are spherical and devoid of a wall, and possess mitochondria, vesicles with electron-dense cores, some concentric membrane bodies and an intact nucleus, but they usually lack chloroplasts.

Case Report: Microtubular Aggregates within the Rough Endoplasmic Reticulum of Embryonal Rhabdomyosarcoma Cells: A Case Report

This study presents a case of embryonal rhabdomyosarcoma (ERMS) of the forearm soft tissue in a 12-year-old female, in which microtubular aggregates in rough endoplasmic reticulum (rER) were noted ultrastructurally. Histologically, tumor cells consisted of typical rhabdomyoblastoid cells with abundant eosinophilic cytoplasm and relatively immature, small tumor cells. Ultrastructurally, two different types of tumor cells were also identified by light microscopy. More than half the tumor cells possessed the characteristic features of rhabdomyoblastic differentiation, such as abundant thick and thin filaments with Z-bands. The other tumor cells were less differentiated cells in which microtubular aggregates (MA) in rER were observed. MA in rER have been described in several nonepithelial tumors, including malignant melanoma, osteosarcoma, extraskeletal myxoid chondrosarcoma, and chordoma. ERMS is another example of mesenchymal tumor in which MA in rER are observed by electron microscopy. Considering the differential diagnosis among mesenchymal tumors, it is important to know that MA can be also observed in ERMS.

Development of the Rough Endoplasmic Reticulum in Incompatible Pollen Tubes of Brugmansia suaveolens (Solanaceae)

After self-pollination of Brugmansia suaveolens, a characteristic stacking of cisternae of the rough endoplasmic reticulum (RER) was seen in pollen tubes. The stacking commenced within less than 6 h after pollination and was the earliest noticeable ultrastructural change. This phenomenon was roughly coincident with a retarded growth rate of the pollen tubes. The RER formed intricate complexes consisting of combinations of two seemingly different arrangements, longitudinally stacked cisternae and concentric stacks. We present a model that interprets the stacked RER profiles as longitudinal sections through cylindrical formations with rounded ends. The appearance of profiles of RER aggregates in electron micrographs is determined by the angle of sectioning. Concentric profiles might be cross sections through such cylinders or sections through rounded or doughnut-shaped appendages.

Decidualization of human endometrial stromal cells in vitro: effects of progestin and relaxin on the ultrastructure and production of decidual secretory proteins*

Decidual cells arise by proliferation and differentiation of endometrial stromal cells of the uterus after appropriate stimulation by ovarian hormones. Previously we have shown that progestin and relaxin stimulate the secretion of several decidual-cell-specific secretory proteins in a long-term primary cell culture system. We now report the effects of progestin and relaxin on the morphology of stromal cells in association with the production rate of two major decidual secretory proteins, prolactin and insulin-like growth factor binding protein-1 (IGFBP-1). Stromal cells were cultured in RPMI 1640 and 2% fetal bovine serum for 22 days under control conditions (no hormone), with relaxin or medroxyprogesterone acetate (MPA), or MPA plus relaxin. Cells treated with MPA alone or MPA plus porcine relaxin grew to a high density with many areas of heaping while control cells and cells grown in medium containing relaxin alone formed discontinuous layers. The cytoplasm was distinguished by aggregates of rough endoplasmic reticulum and secretory granules. Surfaces of cells treated with MPA plus relaxin had clusters of short blunt processes containing secretory granules. The processes were rarely seen in cells exposed to MPA alone and completely absent in control cells or cells exposed to relaxin alone. Intercellular space was greatly widened in cells treated with MPA alone or MPA plus relaxin. There were many extended gap junctions in MPA- and relaxin-treated cells in contrast to controls.(ABSTRACT TRUNCATED AT 250 WORDS)

A case of primary osseous malignant immunoblastic B‐cell lymphoma with intracytoplasmic mu lambda immunoglobulin inclusions

Primary malignant lymphoma of bone, so-called Parker-Jackson reticulosarcoma, is a rare form of extranodal lymphoma with a relatively good prognosis. It often corresponds to B-cell lymphoma of high-grade malignancy. We report a case of mu lambda immunoblastic lymphoma showing two distinctive features: an abundant reactive T-lymphocytic population and unusual intra-cytoplasmic inclusions. These inclusions were PAS positive and consisted of monotypic mu lambda immunoglobulin localized in peculiar aggregates of rough endoplasmic reticulum. Their morphological appearances resembled the well-documented inclusions described in some varieties of non-Hodgkin's lymphoma.

The cytology of dopaminergic and nondopaminergic neurons in the substantia nigra and ventral tegmental area of the rat: A light- and electron-microscopic study

The results of this study support the conclusion that dopaminergic cells can be distinguished from non-dopaminergic cells, at both the light- and electron-microscopic level, by cytological features, and particularly by the pattern of Nissl substance. In both the substantia nigra and the ventral tegmental area, two main categories of cell types can be identified in Nissl preparations: (1) dark-staining, basophilic cells with large masses of Nissl substance (2) light-staining cells with more translucent cytoplasm. The following findings provide evidence that the basophilic cells of both substantia nigra and ventral tegmental area are the dopaminergic cells. (1) There is a good correlation between the topographic distribution of basophilic cells and that of dopaminergic cells mapped by both histofluorescence and immunohistochemical methods. (2) After unilateral destruction of the dopaminergic neurons by intracerebral injection of 6-hydroxydopamine in the dopaminergic pathway, the basophilic cells in the substantia nigra and ventral tegmental area disappeared on the lesion side, while the lighter-staining cells appeared unaffected. (3) In normal rats, and in rats with unilateral 6-hydroxydopamine lesions, intraventricular injection of [ 3H]norepinephrine was used for specific labeling of dopaminergic neurons. In autoradiograms of semithin sections, such labeling was observed only in dark-staining and not in light-staining cells, and in cases of unilateral 6-hydroxydopamine lesion was totally absent on the lesion side. Electron-microscopy showed much of the cytoplasm of the basophilic dopaminergic cells to be densely filled with free ribosomes associated with large, well organized complexes of rough endoplasmic reticulum. The cytoplasm of the light, non-dopaminergic cells contains only sparse free ribosomes and small, widely spaced aggregates of rough endoplasmic reticulum. Both cell types occur in a similar variety of size and shape.

Effect of Some Nucleic Acid Base Analogues and Inhibitors of Protein Synthesis on Orderly Arrangement of Ribosomes in Callus Tissue of Corylus avellana

An embryogenic callus tissue of hazel (Corylus avellana) was used in this study. The meristematic cells of this tissue generate a characteristic rough endoplasmic reticulum (RER) with orderly arrays of bound ribosomes. Some nuclei-acid base analogues and inhibitors of protein synthesis were employed in order to study their action on the formation of these orderly arrays Puromycin did not affect the appearance of RER aggregates and ribosome pairing, although it seemed to reduce their frequency. Cycloheximide, 2-aminopurine and 5-bromouracil suppresed the formation of RER aggregates as well as the pairing of ribosomes. It is concluded that proper nucleic acid and protein synthesis ensuring ribosomal integrity are essential for the structural interaction resulting in the orderly arrays of membrane-bound ribosomes, which are probably pools of ribosomes held in reserve until their recruitment for embryogenesis.

Orderly arrangement of ribosomes in the embryogenic callus tissue of Corylus avellana L.

Cultured callus tissue of hazel (Corylus avellana L.), which has the potency of somatic embryogenesis, was used for the study of cell ultrastructure in the course of callus growth and embryoid formation. The meristematic cells of this tissue exhibit a specific organization of rough endoplasmic reticulum (RER), stacked into extensive parallel sheets. The membranes of the aggregated RER are associated with orderly arrays of bound ribosomes. The high regularity of the alignment of the attached ribosomes seems to be influenced by the distance between the two neighbouring membranes in the RER aggregate. The RER aggregates with orderly attached ribosomes are more frequently found in callus cells and in early embryogenesis than in the advanced stages of embryo development.

Light and electron microscopic studies on the development and liberation of Janczewskia gardneri Setch. spermatia (Rhodophyta)

Abstract Janczewskia spermatia occur in conceptacles and are formed by spermatangial mother cells that originate directly from the inner conceptacular cell layer or from uniseriate filaments. Each spermatangial mother cell produces several spermatangia. Young spermatia are enclosed within an electron dense spermatangial wall and are connected to their respective mother cells by a small septal plug. Reduced chloroplasts are present in the mother cells and in some developing spermatia. As the spermatia mature, the spermatangial wall gelatinizes at the apex of the spermatangium. Subsequently or concomitantly a two-layered spermatial wall forms which ruptures the spermatangium-mother cell pit connection. Rough endoplasmic reticulum aggregates in the posterior end of the spermatium to form spermatial vesicles containing fibrillar material, whereas dictyosome vesicles contribute to the fibrillar material accumulation in later stages. Shortly before or after release from the spermatangial mother cells, the sperm...

Lysosomal and ultrastructural changes in human "toxic" neutrophils during bacterial infection.

"Toxic" neutrophils from humans with severe bacterial infections, identified by the presence of Döhle bodies, "toxic" granules, and vacuoles were shown to differ from normal neutrophils both in ultrastructure and in lysosome activity. Döhle bodies were identified as lamellar aggregates of rough endoplasmic reticulum. Toxic granules corresponded to the azurophilic granules usually identified by Romanowsky stains only in neutrophil precursors. By electron microscopy such granules were large, electron-dense, and peroxidase positive; they could usually be distinguished from the smaller, less dense, "specific" granules also present in control neutrophils, but in the latter they became visible by light microscopy only after prolonged staining or following fixation with glutaraldehyde. These observations suggest that toxic granules represent an abnormal staining reaction of the large dense granules in the toxic cells, and not phagocytized material, newly formed abnormal granules or autophagic bodies. Alkaline phosphatase activity was significantly greater in toxic neutrophils than in normal ones; 80% of the activity of both was located in the lysosome fraction. Beta glucuronidase was normal. Total acid phosphatase was normal, but the percentage located in the nonlysosome fraction of toxic neutrophils was increased, suggesting that lysosomes were "labilized." Formation of neutral red vacuoles in supravitally stained preparations, an index of lysosome activity, occurred more rapidly in toxic neutrophils. This reaction paralleled degranulation and the formation of clear vacuoles in unstained wet mounts and could be blocked by colchicine, a lysosome stabilizer, or enhanced by procedures which activate lysosomes. "Autophagic" vacuoles were observed by electron microscopy in some toxic neutrophils. These observations are discussed in relation to the concept that the "toxic" neutrophils in severe bacterial infection reflect cellular immaturity and/or stimulation or degeneration.