Elements Of Rough Endoplasmic Reticulum Research Articles

Morphology and ultrastructure of the alimentary canal of the cicada Platypleura kaempferi (Hemiptera: Cicadidae)

AbstractThe alimentary canal of cicada Platypleura kaempferi is described. It comprises the oesophagus, filter chamber, external midgut section and hindgut. The elongate oesophagus expands posteriorly, with its posterior end constricting to become a bulb. The filter chamber consists of two parts: a very thin sheath and a filter organ. The filter organ is composed of the anterior and posterior ends of the midgut (internal midgut section), and the internal proximal ends of the Malpighian tubules. The external midgut section differentiates into a collapsed sac and a midgut loop. The latter is divided into three distinct segments. The hindgut contains a dilated rectum and a long narrow ileum. The distal portions of the four Malpighian tubules are enclosed in a peritoneal sheath together with the distal ileum before reaching to the rectum. Ultrastructurally, the oesophagus and the hindgut are lined with a cuticle. The filter chamber sheath consists of cells with large irregular nuclei. Filamentous substances coat the microvilli of the cells of the internal midgut section. The posterior end of the midgut comprises two types of cells, with the first type of cells containing many vesicles and scattered elements of rough endoplasmic reticulum. The anterior and posterior segments of the midgut loop cells have ferritin‐like granules. The ileum cells have well‐developed apical leaflets associated with mitochondria. Accumulations of virus‐like particles enclosed in the membrane are observed in the esophagus, conical segment, mid‐ and posterior segments of the midgut loop.

Anatomy and ultrastructure of the salivary (prosomal) glands in unfed water mite larvae Piona carnea (C.L. Koch, 1836) (Acariformes: Pionidae)

Anatomy and ultrastructure of prosomal salivary glands in the unfed water mite larvae Piona carnea (C.L. Koch, 1836) were examined using serial semi-thin sections and transmission electron microscopy. Three pairs of alveolar salivary glands shown are termed lateral, ventro-lateral and medial in accordance with their spatial position. These glands belong to the podocephalic system and are situated on the common salivary duct from back to forth in the above mentioned sequence. The arrangement of the medial glands is unusual because they are situated one after another on the medial (axial) body line, therefore they are termed anterior and posterior medial glands. The secretory duct of the anterior medial gland mostly turns right, and the duct of the posterior gland turns left. The salivary glands are located in the body cavity partly inside the gnathosoma and in the idiosoma in front of the brain (synganglion). Each gland is represented by a single acinus (alveolus) and is composed of several cone shaped secretory cells arranged around the large central (intra-acinar) cavity with the secretory duct base. The cells of all glands are filled with secretory vesicles of different electron density. The remaining cell volume is occupied by elements of rough endoplasmic reticulum, and the membrane enveloping vesicles may have ribosomes on its external surface. Large nuclei provided with large nucleoli occupy the basal cell zones. The pronounced development of the prosomal salivary glands indicates their important role in extra-oral digestion of water mite larvae.

Cell Adhesion Molecule 1 (CADM1), a Novel Venous Thrombosis Risk Factor, Is Ubiquitously Present In Vascular Endothelium and Smooth Muscle Cells

AbstractAbstract 4316We recently demonstrated that CADM1, interacting with protein C deficiency, is a novel risk factor for venous thrombosis (VT) Blood 114:3084-3091, 2009. CADM1 likely plays a role in maintaining endothelial barrier function. Prior to this study CADM1 had not been identified in endothelial cells. In this study we have determined the distribution of CADM1 in human vasculature. Methods:Human tissue samples representing all organs as well as large vessels were accessioned from archived paraffin blocks from the surgical pathology division of FAHC. Tissue sections were processed for immunoflourescence using as primary antibodies a chicken monoclonal anti-CADM1 IgY antibody (anti-SynCAM/TSLC1 clone 3E1, MBL Inc, Woburn, MA) and anti-smooth muscle actin (SMA) clone 1A4 (Sigma, St. Louis, MO), anti-von Willebrand factor (vWF) rabbit polyclonal antibody (DAKO Inc., Glostrup, DK). vWF staining was used to identify endothelial cells. The secondary antibodies for CADM1, SMA, and vWF were donkey anti chicken alexa 488, donkey anti mouse alexa 647, and donkey anti rabbit alexa 647, respectively. Appropriate negative and positive controls were run. Intensity of staining was rated as absent, trace or present by three observers (TK, DJT, and EGB). Immunoelectron microscopy (IEM) was performed on cultured human umbilical vein endothelial cells (Allcells LLC, Emeryville, CA) using a post embedding procedure with protein-A gold. Peripheral blood leukocytes were evaluated for the presence of CADM1 using the same antibody following cytospin preparation. ResultsCADM1 was found ubiquitously in the macro- and micro-vasculature of all organs as well as the aorta and saphenous vein with intensity of staining showing modest variability from organ to organ. CADM1 staining of SMA was observed in both arterial and venous vessels but was considerably stronger on the arterial side. IEM demonstrated cytoplasmic immunogold staining associated with elements of rough endoplasmic reticulum and actin filaments as well as at the membranes of filopodia. In contrast, peripheral blood monocytes, lymphocytes and granulocytes were negative for CADM1expression. Conclusions:CADM1 is expressed ubiquitously in endothelial and smooth muscle cells of the macro-and micro-vasculature with IEM evidence for its presence in filopodial cytoplasm and membranes. Peripheral blood leukocytes did not show evidence of CADM1 expression. This is the first report of CADM1 positivity in vascular smooth muscle cells. The biological role of CADM1 remains to be determined but its ubiquitous expression in the endothelium of the macro- and micro-circulation, together with an apparent role in endothelial cell motility, suggests an important role in endothelial homeostasis. Disclosures:Bovill:Haemotologic Technologies, Essex Jct., VT: Equity Ownership.

Platelet Pathology in GATA-1 Dyserythropoietic Macrothrombocytopenia.

Germline mutations in the X-linked hematopoietic transcription factor, GATA-1, have been associated with dyserythropoietic anemia (DEA), macrothrombocytopenia (MTP), and congenital erythropoietic porphyria. Recently, morphological features suggestive of the Gray Platelet Syndrome (GPS) were described in a pedigree with a germline R216Q GATA-1 mutation (Blood 106:6a, 2005). The present study has evaluated platelets (Pl) in the electron microscope from members of a previously described pedigree (Blood 98:2681–2688, 2001) with GATA-1 G208S, MTP, and dyserythropoiesis without anemia, for whom detailed platelet morphology studies have not been reported. The presence of a hemizygous GATA-1 mutation was confirmed by conventional fluorescent dye chemistry sequencing of DNA from patient peripheral blood mononuclear cells. Their Pl revealed wide variations in size, shape, internal and external structure. Some normal sized and giant Pl contained usual numbers of alpha granules and dense bodies, while most of the large cells were hypogranular. Some contained no membrane systems or organelles. Others were filled with masses of dense tubular system (DTS) channels, and others contained the tubular inclusions found in the Medich Giant Platelets Disorder (Platelets 15:345–353, 2004). Many of the hypogranular cells contained small vacuoles that may have been enclosing membranes of alpha granules. Except for the tubular inclusions, all of these structural variations are observed in GPS Pl (Am. J. Pathol. 95:445–462, 1979). However, additional striking abnormalities were seen in GATA-1 Pl that are not characteristic of GPS Pl. Many GATA-1 Pl contained unusual, closely associated dense double membranes differing from normal elements of rough endoplasmic reticulum, smooth endoplasmic reticulum, DTS or surface connected open canalicular system (OCS), but resembling channels of the OCS after exposure to EDTA. They were observed previously only in megakaryocytes (Mk) from one family with GATA-1 DEA-MTP (Nat. Genet , 24:266–270, 2000). The dense double membranes were often found in parallel association and, in some examples, isolating areas of cytoplasm. However, the isolated areas were not undergoing autophagic degradation as such areas enclosed by elements of the DTS do in White Platelet Syndrome Pl (Platelets 15:173,2004). Instead, they proved to be another unique feature of GATA-1 platelets, the presence of Pl within Pl. The sequestered cells were usually mature in appearance and often discoid in form with circumferential coils of microtubules. In some GATA-1 Pl there were two Pl within the same cell, and on rare occasions, a Pl within a Pl within a Pl. Pl within Pl have never been observed previously in any human platelet disorder. Another unique feature, related to Pl within Pl, was the frequent Pl to Pl surface attachment of non-activated cells forming large macrothrombocytes with no similarity to aggregates of stimulated normal platelets.Conclusion: The substructural abnormalities of Pl from patients with germline GATA-1 mutations share some overlap with those seen in GPS Pl, but are distinct and unique. The MTP, Pl within Pl and surface Pl to Pl attachments suggest a major defect in the formation and separation of GATA-1 Pl from pro-Pl of the parent Mk, resulting in the MTP characteristic of the disorder.

Oogenesis in ovipositing females of the microtrombidiid mite Platytrombidium fasciatum (C.L. Koch) (Acariformes: Microtrombidiidae)

Summary The process of oogenesis in ovipositing females of the microtrombidiid mite Platytrombidium fasciatum (C.L. Koch, 1836) was investigated by means of transmission electron microscopy. Two ovaries do not fuse at their posterior ends and may be conventionally divided into centrally located compact germarium where oocytes undergo previtellogenesis and prominent peripheral vitellarium consisting of growing oocytes protruding on either sides of the ovaries into surrounding tissues are encompassed only by a basal lamina (tunica propria) (solitary type of oogenesis). Previtellogenic oocytes subsequently grow and contain multiplying mitochondria and prominent Golgi complexes and are characterized by a high rate of synthetic activity. To the end of previtellogenesis, large oval oocytes, tightly packed with elements of rough endoplasmic reticulum and free ribosomes and containing large nucleus, gradually migrate to the ovarian boundaries, coming into contact with a basal lamina. At the onset of vitellogenesis, oocytes form short microvilli on their surface. The processes of yolk accumulation and vitelline envelope formation begin simultaneously and carry out due to endogenous sources. Yolk granules are deposited within the membrane profiles of endoplasmic reticulum and originally occupy a zone just beneath a rim of the cortical ooplasm. In addition to yolk bodies, lipid inclusions are accumulated in the cytoplasm. In the late vitellogenesis, the rarely observed process of extraoocytic obtaining of yolk precursors via pinocytotic activity adds to the main mode of yolk accumulation. The vitelline envelope formation proceeds also intraoocytically due to activity of Golgi complexes, which produce electron-dense globules during early vitellogenesis and small vesicles in the late period. They fuse with plasmolemma to form a vitelline envelope that possesses two distinct layers and in mature egg is devoid of pore canals.

Possible role of monkey gingival fibroblasts in external basement membrane maintenance

Morphological and immunocytochemical investigations were made of the interface between the junctional epithelium and connective tissue in gingiva from young monkeys ( Macaca fuscata). Some fibroblasts with conspicuous cytoplasmic organelles, including the elements of rough endoplasmic reticulum, the Golgi apparatus, and mitochondria, were found close to the external basement membrane in the connective tissue underlying the junctional epithelium. Occasionally, cytoplasmic cell processes either made contact with the lamina densa of the basement membrane or came into direct contact with the plasma membrane of the basal layer of junctional epithelium cells. Fragments of a structure like that of the basement membrane were observed between the process and the basal cells. Fibroblasts could be seen very close to the disrupted portion created by the passage of leukocytes migrating into the junctional epithelium through the external basement membrane. Immunoperoxidase methods demonstrated a positive reaction product for laminin on the external basement membrane. This product was observed in the rough endoplasmic reticulum of junctional epithelium cells and of gingival connective tissue fibroblasts located close to the junctional epithelium basement membrane. The cytoplasm of fibroblasts distant from the epithelium, however, demonstrated no immunoreactivity. These results suggest that, in cooperation with epithelial cells, some fibroblasts located near the junctional epithelium can produce such basement membrane components as laminin and that these components may serve to stabilize and/or restore previously assembled basement membrane.

The Origin of Cortical Vesicles and their Role in Egg Envelope Formation in the "Spiny" Eggs of a Calanoid Copepod, Centropages velificatus

The mature oocytes of the marine calanoid copepod, Centropages velificatus, contain two morphologically distinct populations of cortical vesicles that undergo sequential exocytoses at the time of spawning. The contents of the primary cortical vesicles are released first and form the primary egg envelope. This is followed by the exocytosis of the secondary cortical vesicles. These contain numerous intracisternal granules that, upon release into the perivitelline space, transform into a mass of fine fibers. The continual accumulation of fibers constitutes an extracellular matrix between the primary envelope and the egg's plasmalemma. Further amassment of the fibers beneath the primary egg envelope results in the formation of long, spiny projections. The evolution of the cortical vesicles was traced to the early vitellogenic oocytes and appears to be unique. The two populations of cortical vesicles are synthesized together within the same cisternal elements of rough endoplasmic reticulum (RER). The RER originates from membranous blebs off both the nuclear membrane and stacks of annulate lamellae in the early vitellogenic oocytes. Numerous intracisternal granules are present within the RER. Some of these granules fuse, forming a dense, ring-like structure in the extremities of the cisternae. These bud off from the RER to become the primary cortical vesicles. The unfused intracisternal granules remain as discrete bodies within irregular profiles of vesicular ER and comprise the secondary cortical vesicles.

Cytological studies of the susceptible reaction of sugarbeet roots to Heterodera schachtii

The cellular alterations induced in sugarbeet by Heterodera schachtii were studied at 3 and 12 days after nematode inoculation. Three days after inoculation the procambial cells involved in the nematode feeding were already transformed into a syncytium with ultrastructural features which indicated high metabolic activity. Feeding tubes produced by interaction of nematode saliva with the cell contents were observed; in their vicinity the cytoplasm was devoid of cell organelles except for smooth endoplasmic reticulum. Spiny structures occurred in the parenchyma syncytial cells and they appeared to be related to endoplasmic reticulum and dictyosomes; the relation could be functional and it is possible that the spiny component is involved in protein synthesis. Nuclei were enlarged and amoeboid in form and sometimes they migrated through a space in the cell wall. Conspicuous elements of rough endoplasmic reticulum, arranged in concentric layers and actively synthesizing, and plastids with dense inclusions indicating bulk protein synthesis, were detected in parenchyma cells, adjacent to syncytia. Twelve days after nematode inoculation the ground cytoplasm of the syncytia was densely packed, but without vacuoles and the membrane system resembled endoplasmic reticulum. At this time the modification of the cytoplasm and cell wall appeared to be involved in the rapid solute uptake which would be essential for nematode development.

Massive ribonucleoprotein bodies in gametophyte vegetative cells of the mossTimmiella barbuloides (Brid.) Moenk

Vegetative cells of the gametophyte phase of the mossTimmiella barbuloides (Pottiales) are characterized by large cytoplasmic bodies of spherical shape (SBs) whose ribonucleoprotein composition is cytochemically demonstrated. SBs seem to be derived from massive aggregation of cytoplasmic ribosomes, with possible participation by rough endoplasmic reticulum elements. SBs have been found in stereids, parenchymatous cells and young hydroids of the gametophyte stem, and in euricysts of the leaf nerve. The SBs develop early in the course of cell differentiation and, once formed, persist until advanced stages of cell senescence.

Vaginal hemangiopericytoma: A light microscopic and ultrastructural study

A case of a vaginal hemangiopericytoma in a 20-year-old woman was studied by light and electron microscopy. The neoplastic cells had round-to-oval nuclei with one or two nucleoli; fine chromatin; a foamy, cyanophilic cytoplasm; and an increased nuclear cytoplasmic ratio. Light microscopically, the tumor was composed of spindle-shaped or round cells proliferating around vascular spaces. Mitotic figures, necrosis, and hemorrhage were difficult to find. Electron microscopically, the neoplastic cells occurred in clusters, each of which was enclosed by a basal lamina. The cytoplasm contained abundant free ribosomes, flattened elements of rough endoplasmic reticulum, small Golgi apparatus, round or elongated mitochondria, lysosomes, glycogen particles, and sometimes pinocytotic vesicles and bundles of microfilaments with large dense spots. Desmosomes were also seen. In addition, the cytoplasmic process of the benign vascular pericytes was directly in contact with the neoplastic cells which had varying degrees of cytodifferentiation. The neoplastic cells in this lesion are consistent with an origin from pericytes, confirming the findings of this neoplasm when it arose in other sites.

Ultrastructural Differentiation of an Unusual Structure Lining the Anticlinal Walls of the Inner Secretory Cells in Tamarix Salt Glands

The lateral walls of the inner pair of secretory cells in Tamarix aphylla L. salt glands are bordered by an unusual structure, the interfacial apparatus (IA), which is an extraplasmic structure of two asynchronously formed connected parts. The upper part of the IA initially consists of a complex system of waxy layers; later, many large cytoplasmic vesicles with a lipoidal content appear to empty into this part. The lower part of the IA is smaller than the upper and contains proteinaceous material. The lower part is often found in close association with vesicular profiles or cisternal elements of rough endoplasmic reticulum. The possible functional significance of the IA is discussed.

Localization of proteoglycan core protein in subcellular fractions isolated from rat chondrosarcoma chondrocytes.

Chondrocytes from the Swarm rat chondrosarcoma were pulse-labeled with [3H]serine for 30 min and chased, in the presence of cycloheximide, for times up to 300 min. The movement of newly synthesized core protein precursor of the proteoglycan through elements of the endoplasmic reticulum and Golgi complex was examined. Rough and smooth microsome fractions were obtained by centrifuging postmitochondrial supernatants from cell homogenates on discontinuous sucrose gradients. The core protein precursor was identified in subcellular fractions by (a) immunoprecipitation with an antiserum directed against the hyaluronate binding region of the core protein and the link protein and (b) its size on polyacrylamide gels. Labeled core protein precursor decreased from the microsomes with a t1/2 of 60 +/- 8 min, nearly the same as for the appearance of label in completed proteoglycan monomer (t1/2 = 58 +/- 13 min), consistent with a precursor-product relationship. After correcting for incomplete recovery of the core protein precursor in the microsomal fractions and for cross-contamination of the smooth microsomes by elements of rough endoplasmic reticulum, the redistribution of core protein precursor and completed proteoglycan in the intracellular compartments and of labeled extracellular proteoglycan were fit to a three-compartment model. A t1/2 of 98 +/- 7 min for the loss of core protein precursor from the rough microsomes and a t1/2 = 10 +/- 4 min for the completed proteoglycan in the intracellular compartment (Golgi and secretory vesicles) was obtained. The data indicate that at least 70% of the intracellular transit time for the core protein precursor is spent in the rough endoplasmic reticulum. The addition of glycosaminoglycan chains followed by secretion from the cell occurs relatively rapidly, occupying less than 30% of the total intracellular dwell time.

Structural changes in bovine oocytes during final maturation in vivo

AbstractOn the basis of structural observations bovine oocytes were grouped into four successive classed: 0, those before the luteinizing hormone (LH) surge; 1, those up to 8 h following the LH peak level; 2, those between 8 and 19 h after the LH peak level; and 3, those between 19 h after the LH peak level and ovulation.Oocytes in class 0 had mitochondria located in a generally peripheral position. Interior to the mitochondria were elements of rough endoplasmic reticulum (RER) and numerous membrane‐bound vesicles which bore ribosome‐like particles on their outer surface. The first visible changesater the LH peak level as seen in class 1 were the formation of the periviteline space with loss of contact between the cumulus cells and the oocyte, and ruffing of the nuclear envelope. These changes were followed b the resumption of meiosis as defined by germinal‐vesicle breakdown (GVBD), the disappearance of RER, and the formation fo clusters of mitochondria in association with lipid droplets and elementrs of smooth endolasmic reticulum (SER).The period between 8 and 19 h following LH peak level (class 2) was characterized by intensive clustering of mitochoncria in association with lipid droplets and elements of SER, conversion of lipid, fusion of vesicles, and the appearance of ribosomes in the cytoplasm. During the final stage (class 3), the polar body was extruded, the mitochondria dispersed, and the majority of the organelles became located toward the center of the cell. The relatively organelle‐free cortical region contained cortical granules immediately adjacent to the plasma membrane together with aggregates of tubular SER. The structural changes are discussed in the context of follicular steroidogenesis and oocyte developmental competence.

Fine structural aspects on the renewal and development of surface mucous cells and glandular cells of the gastric body of the adult golden hamster.

By light and electron microscopic autoradiography using 3H-thymidine, the renewal and development of surface mucous cells and glandular cells in the gastric body were studied in normal young adult golden hamsters. The isthmus and neck regions of the gastric gland are composed of immature surface mucous cells, immature parietal cells, young parietal cells and mucous neck cells. It is presumed that the stem cell having the potency of differentiating into various kinds of cells is not present in the gastric mucosa of the adult golden hamster. Immature surface mucous cells, located in the isthmus region and capable of synthesizing DNA, contain abundant free ribosomes and a small number of secretory granules. The secretory granules increase in number as the cells ascend towards the gastric surface, forming a thick granule zone in the cell apex. The cells further contain small electron lucent vesicles which are likely involved in the formation of glycocalyx. The immature parietal cells in a low differentiated state, possessing the DNA synthesizing ability, are rarely found in the isthmus. They show collapsed intracellular canaliculi with long microvilli and contain numerous free ribosomes but smooth tubular elements are difficult to recognize. Some of the mucous neck cells located in the isthmus to neck region and capable of synthesizing DNA, are characterized by abundant free ribosomes, a few elements of rough endoplasmic reticulum relatively well developed Golgi apparatus and a few dense secretory granules. Mature surface mucous cells contain abundant secretory granules filling an apical granule zone. They are fated to be degenerated, and extruded into the gastric lumen. This is considered to be a holocrine process. The middle and basal regions of the gland consist mainly of chief cells, parietal cells and endocrine cells. A few of the chief cells in the middle part of the gastric gland also have the activity of synthesizing DNA. Some of the immature cells in the isthmus region, and mature glandular cells in the bottom of the gland are degenerated and phagocytosed by neighboring epithelial cells. This paper also records the occurrence of smooth muscle fibers in the lamina propria, extending from the muscularis mucosae to the basal part of the degenerated surface epithelium.

Ultrastructural study on the regeneration of the junctional epithelium following gingivectomy (author's transl)

The present experiment was undertaken to study about early stages in the regeneration of the junctional epithelium following gingivectomy in rats. Gingivectomy was carried out on the lingual side of the maxillary molar teeth. At intervals of 0 hour to 28 days post-operatively, the maxillary molar teeth were extracted with the surrounding gingiva and coronal portion of the alveolar crest in situ. The sections were examined in light and electron microscope. The results were followed.1) After 2 days, the epithelial cells were put in contact with the enamel. New junctional epithelium was consisted of the oral epithelium. The junctional epithelium was attached to the enamel surface by means of the basal-lamina-like structure and halfdesmosomes.2) After 3 to 5 days, the junctional epithelium was consisted of the same epithelial cells both the apical and the coronal parts. These newly formed epithelial cells of the apical part provided with welldeveloped Golgi complexes, elements of rough endoplasmic reticulum, but the epithelial cells of the coronal part possessed few organelles. From these results, it was postulated that the epithelial cells had migrated from the apical toward the coronal part. In the junctional epithelium, the epithelial cells seemed to be always supplied and renewed from the oral epithelium. The sulcular epithelium was consisted of keratinized epithelium.3) Formation of the new junctional epithelium following gingivectomy was completed in 28 days. The cells of new junctional epithelium were provided with the Golgi complexes, elements of endoplasmic reticulum. The junctional epithelial cells showed appearances of numerous intracytoplasmic vacuoles. The cells constituting the coronal part of the oral sulcular epithelium showed keratinization.It seems, therefore, that the gingival sulcus following gingivectomy in rats had been reformed by the newly formed junctional epithelium and the keratinized oral sulcular epithelium.

Cytological study on water stress during germination of Zea mays

Kernels of Zea mays were subjected to dehydration treatment at various times during germination. Embryos from kernels dehydrated during the first 36 h of germination are resistant to dehydration and subsequently germinate earlier than controls. Dehydration of kernels germinated during 72h leads to an irreversible arrest of growth of the embryos. However, autoradiographic observations showed that these embryos are still able to incorporate [(3)H] uridine and probably [4-5-(3)H] lysine. Incorporation of [(3)H] thymidine does not occur. The effect of dehydration on root ultrastructure was studied. In embryos dehydrated after 24 h and 72 h of germination, condensation of chromatin is seen and association of elements of rough endoplasmic reticulum with vacuoles and glyoxysomes can be noted. These changes are reversible in drought-resistant embryos and irreversible in drought-sensitive embryos. However, more notable changes than those seen after 24 h can be observed in embryos dehydrated after 72 h of germination: mitochondria and proplastids can not be distinguished with certainty, glyoxysomes fuse and preferably dispose at the periphery of the cell. Rehydration of drought-sensitive embryos causes breakdown in plasma and nuclear membranes, which leads to the loss of cellular compartimentalization. Moreover, the chromatin remains definitively condensed and has lost its function of genetic regulation.

Rod-shaped filamentous inclusions and other ultrastructural features in a cerebellar astrocytoma

A biopsy specimen of a cerebellar astrocytoma from a 14-year-old girl was studied by light and electron microscopy. Histologically the tumor showed a mixture of loose and compact areas with numerous Rosenthal fibers. By electron microscopy most tumor cells contained, besides the usual organelles, large amounts of 70 to 100 A thick filaments. Classical Rosenthal fibers were also identified. In addition many cell bodies and processes were sprinkled with fragments of Rosenthal fiber material. Ordered filamentous arrays (so-called Hirano bodies) were seen in a number of tumor astrocytes. They are considered to be a nonspecific arrangement of filament units largely devoid of cytopathologic significance. Other ultrastructural features of some tumor cells were inchoate forms of the granulated bodies of conventional histology, paired cisternal elements of rough endoplasmic reticulum, and honeycomb-like profiles of transversely cut cylindrical units of smooth endoplasmic reticulum. Microtubular bodies were numerous in the endothelial cells of the tumor vessels.

Some findings on the fine structure of the neurohypophysis in dehydrated and pitressin-treated mice.

The fine structure of the pituitary posterior lobe was observed using normal, dehydrated and Pitressin-treated mice. The normal posterior lobe of the mouse contains numerous neurosecretory granules of about 1,300-2,000 angstrom diameter in the nerve terminals. These granules are often found in contact with neurotubules running longitudinally in the axon. In the 2, 5 and 7 day-dehydrated animals the secretory granules are markedly decreased in number, while small vesicles of about 500 angstrom diameter are conspicuously increased in number in the nerve terminal. It is very difficult to obtain an electron microscopic figure of the exocytosis of the secretory granule. The cluster of small vesicles in the nerve terminal is sometimes surrounded by an electron dense membrane and gradually changed to the cytolysomes. These facts suggest that most of these vesicles are not synaptic vesicles containing acetylcholine but materials derived from the limiting membrane of the released granules and they are gradually disposed of by lysosomes. In Pitressin-treated animals (3 days, 200mU/day), an increase in number of the neurosecretory granules and an appearance of the disposal process of the excess neurosecretory granules are characteristic in the nerve terminal. Some granules are aggregated to become higher in electron density and surrounded by an electron dense membrane. They are positive for acid phosphatase reaction and are degenerated by an autolytic process. In both cases above, the pituicytes showed a marked reaction. The elements of rough endoplasmic reticulum and the Golgi apparatus become well developed and many large lysosomes are seen in the cytoplasm.

Ultrastructural variations in N,N'-bis(4-aminophenyl)-N,N'-dimethylethylenediamine (BED) oxidase localization in rat liver and parotid gland with variation in length of fixation.

The localization and reactivity of a terminal oxidase which oxidizes N,N'-bis(4-amino-phenyl)-N,N'-dimethylethylenediamine (BED) were studied in rat liver and parotid gland after varying the concentration of formaldehyde fixative and the length of fixation. Reaction product was observed in mitochondrial outer compartments, smooth elements of rough endoplasmic reticulum, some Golgi lamellae, perinuclear membranes and cytoplasmic membranous structures often associated with mitochondria. A reaction also occurred in the limiting membrane and, to some degree, in the material comprising the secretory granules of the parotid. The reaction in the mitochondrial outer compartment was extremely formaldehyde-sensitive. Controls in which diaminobenzidine (DAB) was substituted for BED showed reaction only in mitochondrial cristae and outer compartments, whereas controls without either reagent showed no reactivity.

Membrane-bound ribosomes in HeLa cells: I. Their proportion to total cell ribosomes and their association with messenger RNA

The ribosomes associated with the endoplasmic reticulum in HeLa cells have been the object of an electron microscopic and biochemical investigation. An appreciable amount of elements of rough endoplasmic reticulum, in the form of tubules, vesicles, and short cisternae scattered throughout the cytoplasm, has been observed by electron microscopic examination of thin sections of these cells. From the distribution of rRNA among the subcellular fractions, it has been estimated that from 10 to 15% (and possibly as many as 20%) of the total ribosomes in HeLa cells are associated with elements of rough endoplasmic reticulum. 65 to 70% of these ribosomes can be recovered as polysomes after sodium deoxycholate treatment and are presumably engaged in protein synthesis in vivo. Treatment with EDTA releases essentially all the small subunits and about 70% of the larger subunits of the endoplasmic reticulum-bound ribosomes: these respond, therefore, to EDTA treatment similarly to ribosomes of the rough endoplasmic reticulum from rat liver.