Rough-surfaced Endoplasmic Reticulum Research Articles

Physiological and transcriptome analysis of Mytilus coruscus in response to Prorocentrum lima and microplastics

Nowadays, diarrheic shellfish toxicity (DSP) toxin and microplastics (MPs) are commonly found in coastal waters worldwide. Due to their widespread use, their persistence and toxicity, they may induce adverse effects on Mytilus coruscus. However, the underlying toxic mechanisms of DSP and MPs on M. coruscus remain unclear. This study explored the physiological index and transcriptome change of the digestive gland of adult M. coruscus exposed for 3 days to polystyrene (PS) MPs (0.2 mg/L, 90-100 μm) and Prorocentrum lima alone or in combination. The results showed that the CAT activity and MDA content significantly increased, respiration rate and feeding rate significantly decreased. The combination of MPs and P. lima caused more structural damage to the rough surface endoplasmic reticulum and mitochondria in the digestive glands of M. coruscus. The transcriptome analysis showed that 485 and 220 genes were up- and down-regulated, respectively, after exposure to P. lima; 1,989 up-regulated DEGs and 1,098 down-regulated DEGs were identified after exposure to MP treatment, and 1,004 up-regulated DEGs and 664 down-regulated DEGs were identified after exposure to the combination of P. lima and MPs. The DEGs were mainly enriched in the lysosome, mRNA surveillance pathway, carbon metabolism, the mTOR signaling pathway, the complement and coagulation cascades, and the TNF signaling pathway. The MP, P. lima exposure mainly induced the expression of RNA-binding protein musashi, serine/arginine repetitive matrix protein 1, low affinity immunoglobulin epsilon Fc receptor, toll-like receptor 2, caspase 7, calmodulin, E3 ubiquitin-protein ligase, serine/threonine-protein kinase PRP4, glutathione S-transferase, and heat shock 70 kDa protein. MPs and P. lima poison mainly influence the expression of RNA transport, immune related gene, apoptosis, signal related gene, and antioxidant gene change. The combination of MPs and P. lima has a synergistic toxic effect. This study provides a new insights into its physiological and molecular responses of M. coruscus to MPs and P. lima toxic exposure.

Morphology and ultrastructure of the tarsal adhesive organs of the Madagascar hissing cockroach Gromphadorhina portentosa.

The present transmission and scanning electron microscopic study of the ultramorphology of the pliable attachment pads (arolium, euplantulae) of the Madagascar hissing cockroach Gromphadorhina portentosa reveals structural evidence for their function in producing, storing, and secreting an adhesion-mediating secretion and releasing it to the exterior. The exocrine epidermal tissue of both the arolium and the euplantula is significantly enlarged by numerous invaginations stretching into the hemolymph cavity. Its cells show large nuclei, numerous mitochondria, Golgi complexes, and a prominent rough-surfaced endoplasmic reticulum integrated within an electron-dense cytoplasm that contains numerous vesicles of diverse electron density and size. Invaginations of the cell membrane provide evidence for strong membrane turnover. The glandular epithelium of both the arolium and the euplantula releases the adhesion-mediating secretion into a subcuticular void from which it has to permeate the thick cuticle of the adhesive pads. The subcuticular void is compartmentalized by cuticle bands through which the adhesion-mediating secretion permeates via small canals. The secretion subsequently enters a larger storage reservoir before being received by a prominent sponge-like cuticle. The structural differences between the arolium and the euplantula consist of the number and length of the interdigitations spanning the hemolymph cavity, of the subdivision of the subcuticular reservoir by cuticle bands, and of the thickness of the sponge-like cuticle. The structural results are discussed with respect to the production of a chemically complex (emulsion-like) adhesive, its controlled release to the exterior, and the micromechanical properties of the cuticle of the pliable pad.

A Case of Over-the-Counter, Drug-Induced Autoimmune Hepatitis: Immunohistochemical and Electron Microscopic Studies

Introduction: In daily clinical practice, drug-induced liver injury(DILI) can always be a cause of liver injury in patients taking medications. Over-the-counter(OTC) drug: Pabron has been purchasing at the pharmacy in Japan, Thailand, Malaysia, and Chinese Taipei as a multi-component cold medicine. We desribed a case of DI-autoimmune hepatitis(AIH) from OTCdrug: Pabron gold®. Case description: A 64-year-old man sought treatment for common cold and was admitted for general fatigue and liver dysfunction. Blood test results included total bilirubin (T-bil), 2.4 mg/dL; direct bilirubin (D-bil), 1.4 mg/dL; AST, 1,244 IU/L; ALT 1,455 IU/L; ALP 1,242 IU/L; and γ-GTP 599, IU/L. Viral hepatitis serology was negative. Other relevant data included IgG level, 1,907 mg/dL; IgM, 95 mg/dL; ANA x80 (cut-off, < x40); ASMA x20 (cut-off, OTC, namely Pabron Gold®, prior to disease onset which was suspected as the cause of liver injury. A DI lymphocyte stimulation test for Pabron Gold® was positive, 2,447 cpm (503%) (< 179%). The liver biopsy revealed spotty necrosis and the accumulation of ceroid pigment in Kupffer cells around central vein, and piecemeal necrosis with multiple plasma cells around portal tracts. Moreover, the plasmocytic infiltration showed positive CD79a staining while negative CD20 staining. Ultrastructually, “cart-wheel” chromatin configuration in the nucleus was observed in some of plasma cells packing with a lot of rough-surfaced endoplasmic reticulum. Moreover, the characteristic granular osmiophilic materials and lipid droplet were observed in Kupffer cell. HLA typing test was HLA-DR4 positive. The score based on simplified criteria for autoimmune hepatitis diagnosis was 6, probable. With a persistent rise in aminotransaminase levels, the patient was started on steroids with predonine prescribed to control the hepatic inflammation. Discussion: This report is the first to describe a case of DI-AIH following the use of an over-the-counter drug. In fact, DI-AIH diagnosis represents a challenge to the clinician because neither histological nor clinical pathognomonic features of AIH exist. We described a case of OTC Pabron gold®-associated liver injury, diagnosed as DI-AIH, calling for caution in the use of OTC.

Mechanism underlying acute lung injury due to sulfur mustard exposure in rats.

Sulfur mustard (SM), a bifunctional alkylating agent that causes severe lung damage, is a significant threat to both military and civilian populations. The mechanisms mediating the cytotoxic effects of SM are unknown and were investigated in this study. The purpose of this study was to establish a rat model of SM-induced lung injury to observe the resulting changes in the lungs. Male rats (Sprague Dawley) were anesthetized, intratracheally intubated, and exposed to 2 mg/kg of SM by intratracheal instillation. Animals were euthanized 6, 24, 48, and 72 h post-exposure, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. Exposure of rats to SM resulted in rapid pulmonary toxicity, including partial bronchiolar epithelium cell shedding, focal ulceration, and an increased amount of inflammatory exudate and number of cells in the alveoli. There was also evidence that the protein content and cell count of BALF peaked at 48 h, and the alveolar septum was widened and filled with lymphocytes. SM exposure also resulted in partial loss of type I alveolar epithelial cell membranes, fuzzy mitochondrial cristae, detachment and dissociation of ribosomes attached to the surface of rough endoplasmic reticulum, cracked, missing, and disorganized microvilli of type II alveolar epithelial cells, and increased apoptotic cells in the alveolar septum. The propylene glycol control group, however, was the same as the normal group. These data demonstrate that the mechanism of a high concentration of SM (2 mg/kg) induced acute lung injury include histologic changes, inflammatory reactions, apoptosis, oxidative stress, and nuclear DNA damage; the degree of injury is time dependent.

Ultrastructural immunolocalization of laminin 332 (laminin 5) at dento-gingival interface in Macaca fuscata monkey.

Although laminin 332 (laminin 5), an extracellular matrix molecule involved in cell adhesion and migration, has been localized at the interface between the tooth enamel and junctional epithelium, its ultrastructural localization remains to be fully clarified. The purpose of the present study was to investigate the ultrastructural distribution of laminin 332 at the dento-gingival interface in Japanese monkey (Macaca fuscata) using pre- and post-embedding immunoelectron microscopy. Pre-embedding immunoelectron microscopy revealed a broad band of internal basal lamina together with supplementary lamina densa, and both showed immunolabeling for laminin 332. Immunoreaction products for laminin 332 were observed in the rough-surfaced endoplasmic reticulum of the junctional epithelial cells close to the tooth enamel. Post-embedding immunoelectron microscopy revealed an increase in the number of immunogold particles toward the coronal portion, resulting in a large accumulation of particles on the basal lamina, preferentially on the lamina densa. Concomitantly the dental cuticle at the dento-gingival interface was sporadically, but specifically, immunogold-labeled with anti-laminin 332 antibody. These data suggest that junctional epithelium actively produces laminin 332, and that the products accumulate at the dento-gingival interface during cell migration coronally towards the gingival sulcus.

Developmental effects of oral exposure to diethylstilbestrol on mouse placenta

Placental growth and function are of biological significance in that placental tissue promotes prenatal life and the maintenance of pregnancy. Exposure to synthetic estrogens causes embryonic mortality and placental growth restriction in mice. The aim of the present study was to examine the effects of diethylstilbestrol (DES) on placenta in mice. DES at 1, 5, 10 or 15 µg kg(-1) day(-1) , or 17β-estradiol (E2 ) at 50 µg kg(-1) day(-1) , was administered orally to ICR mice on days 4 through to 8 of gestation. Expression of ERα, ERβ, ERRβ or ERRγ mRNA in the junctional or labyrinth zone of the placentas on day 13 was assessed using RT-PCR, as well as the embrynic mortality, embryonic and placental weight, histological changes of labyrinth and ultrastructural changes of the trophoblast giant cells (TGCs). Embryo mortalities in the DES 10 and 15 µg kg(-1) day(-1) groups were markedly increased. No significant changes in embryonic and placental weight were observed in any DES- or E2 -exposed groups. Expression of ERα mRNA in the junctional zone with male embryos in the 5 µg kg(-1) day(-1) group was significantly higher than that in the control, whereas expression was not determined in the 15 µg kg(-1) day(-1) group. Histological observation revealed that the placentas exposed to DES at 10 µg kg(-1) day(-1) lacked the developing labyrinth. Ultrastructural observation of the TGCs showed poor rough-surfaced endoplasmic reticulum in the DES 10 µg kg(-1) day(-1) group. The present data suggest that developmental changes induced by DES may be related to interference with the nutrition and oxygen exchange between mother and embryo or decreased protein synthesis, resulting in a high frequency of embryo mortality.

D469del-COMP Retention in Chondrocytes Stimulates Caspase-Independent Necroptosis

Mutations in the cartilage oligomeric matrix protein gene (COMP) cause pseudoachondroplasia (PSACH). This dysplasia results from the intracellular retention of mutant COMP protein and premature death of growth-plate chondrocytes. Toward better understanding of these underlying mechanisms, we examined D469del-COMP activation of the unfolded protein response and cell death pathways in rat chondrosarcoma cells. Using an inducible expression system, we examined the effects of D469del-COMP retention after 4 days of mRNA expression and then 5 days without inducing agent. Retention of D469del-COMP stimulated Chop (Ddit3) and Gadd34 (Ppp1r15a) and triggered reactivation of protein translation that exacerbated intracellular retention. High levels of Nox4 and endoplasmic reticulum receptor stress-inducible Ero1β generated reactive oxygen species, causing oxidative stress. Increased expression of Gadd genes and presence of γH2AX indicated that DNA damage was occurring. The presence of cleaved apoptosis inducing factor (tAIF) and the absence of activated caspases indicated that retention of D469del-COMP triggers cell death in chondrocytes by necroptosis, a caspase-independent programmed necrosis. Loss of growth-plate chondrocytes by necroptosis was also found in our pseudoachondroplasia mouse model. These results suggest a model in which D469del-COMP expression induces persistent endoplasmic reticulum stress, oxidative stress, and DNA damage, thus priming chondrocytes for necroptosis. We define for the first time the precise mechanisms underlying D469del-COMP pathology in pseudoachondroplasia and suggest that oxidative stress and AIF may be promising therapeutic targets.

Ultrastructural and in vivo confocal microscopic evaluation of interface after Descemet’s Stripping Endothelial Keratoplasty in rabbits

To study healing at the donor-recipient interface after Descemet's Stripping Endothelial Keratoplasty (DSEK) in rabbits by ultrastructural and in vivo confocal microscopic evaluation. The right eye of eight New Zealand White rabbits underwent DSEK. Postoperatively, each rabbit was subjected to routine slitlamp examination daily for 2 weeks and then weekly for 6 weeks. In vivo confocal microscopic evaluation was performed at 1, 2, 4 and 8 weeks. Two rabbits were randomly chosen at 1, 2, 4 and 8 weeks for transmission electron microscopic examination. Interface haze decreased with each follow-up visit. Activated keratocytes and associated cellular processes were evident throughout all the follow-ups with in vivo confocal microscopy. Highly reflective particles were left at the interface until the end-point of the study. Upon ultrastructural evaluation, increased rough-surface endoplasmic reticulum in keratocytes, clefts, folds and retained Descemet's membrane (DM) were found. Clefts lack of adherence at the interface and degenerated keratocyte may make up the highly reflective particles. In addition, retained DM does not appear to affect adhesion and very minimal healing is produced at the DM-stroma smooth interface, which permits better quality of vision in Descemet's membrane endothelial keratoplasty.

Chondroid chordoma of the skull base: immunohistochemical and ultrastructural study of two cases with special reference to microtubules within rough-surfaced endoplasmic reticulum

Two cases of skull base chordoma (case 1, a 57-year-old woman; case 2, a 69-year-old woman) were investigated immunohistochemically and ultrastructurally. The tumors showed histopathological features typical of chondroid chordoma and contained both classical chordomatous and hyaline cartilaginous components. Tumor cells were immunoreactive for cytokeratin, vimentin, and S-100 protein, but negative for microtubule-associated protein 2 and class III beta-tubulin (tub-B3). Tumor cells of case 2 were immunoreactive for tau-protein and class II beta-tubulin (tub-B2), whereas those of case 1 were negative. Ultrastructurally, tumor cells in both cases showed the presence of abundant glycogen granules, well-developed intracellular organelles, and desmosome-like junctions. In case 2, several microtubules were closely packed and ran parallel or in random directions within the dilated cisterns of rough-surfaced endoplasmic reticulum (rough ER). "Microtubules within rough ER" has been described in several neoplasms, including classical and chondroid chordomas. Although previous reports documented the tub-B3 immunoreactivity in chordomas, our results suggested that, in our case 2, the predominant isoform of beta-tubulin in microtubules within rough ER was not tub-B3 but tub-B2.

Ultrastructural differences in the endoplasmic reticulum among various pituitary tumor types

Our aim was to reveal ultrastructural differences in the endoplasmic reticulum (ER) among surgically removed human pituitary tumors. More than 2000 pituitary tumors were studied by electron microscopy. In growth hormone (GH) adenomas, the ER is well developed and consists mainly of rough surfaced endoplasmic reticulum (RER) and few ER membranes without ribosomes, called smooth surfaced endoplasmic reticulum (SER). In the sparsely granulated GH adenomas, the ER is less prominent and is seen in fibrous bodies containing keratin immunopositive microfilaments. In prolactin (PRL) adenomas, the RER is conspicuous, forming concentric whorls. In adenocorticotropin (ACTH) and thyroid stimulating hormone (TSH) adenomas, the ER and consists of RER and to a lesser extent, SER. In gonadotroph adenomas and null cell adenomas, the ER is poorly developed. In GH adenomas exposed to somatostatin analogs and in prolactin adenomas exposed to dopamine agonists, regression of ER is noted. In pituitary carcinomas, the ER is recognizable but it is less extensive than in the benign neoplasms. In conclusion, the ultrastructural investigation of ER provides valuable information on the cytogenesis and cellular composition of pituitary tumors. There is also a mild correlation between endocrine activity and extent of ER. However, no correlation exists between invasive and non‐invasive tumors and growth potential. Pituitary carcinomas cannot be distinguished from benign adenomas based on the ultrastructural features of ER.

An Inducible Cartilage Oligomeric Matrix Protein Mouse Model Recapitulates Human Pseudoachondroplasia Phenotype

Cartilage oligomeric matrix protein (COMP) is a pentameric extracellular protein expressed in cartilage and other musculoskeletal tissues. Mutations in the COMP gene cause pseudoachondroplasia (PSACH), a severe dwarfing condition that has a growth plate chondrocyte pathology. PSACH is characterized by intracellular retention of COMP and other extracellular matrix (ECM) proteins, which form an ordered matrix within large rough endoplasmic reticulum cisternae. This accumulation is cytotoxic and causes premature chondrocyte cell death, thereby depleting chondrocytes needed for normal long bone growth. Research to define the underlying molecular mechanisms of PSACH has been hampered by the lack of a suitable model system. In this study, we achieved robust expression of human mutant (MT) or wild-type (WT) COMP in mice by using a tetracycline-inducible promoter. Normal growth plate distribution of ECM proteins was observed in 1-month-old WT-COMP and C57BL\6 control mice. In contrast, the structure of the MT-COMP growth plate recapitulated the findings of human PSACH growth plate morphology, including (1) retention of ECM proteins, (2) intracellular matrix formation in the rER cisternae, and (3) increased chondrocyte apoptosis. Therefore, we have generated the first mouse model to show extensive intracellular retention of ECM proteins recapitulating the human PSACH disease process at the cellular level.

The role of interferon-gamma in lymphocytic thyroiditis: its functional and pathological effect on human thyrocytes in culture

Interferon-gamma (IFN-gamma) has been recognized to possess diverse non-immunological effects on epithelial cells such as cellular growth and differentiation. We have previously demonstrated that IFN-gamma suppressed thyroid-stimulating hormone (TSH)-stimulated thyroglobulin (TG) synthesis in human thyrocytes through inhibition of TG gene transcription. To define the pathological mechanism involved in the action of IFN-gamma, we studied the ultrastructural changes of human thyrocytes cultured in monolayer. Stimulation of the thyrocytes with TSH 10 mU/ml for 2 days resulted in marked increase in TG release into the medium. This was accompanied by elongation of microvilli, increase in follicles and acinar formation, increase in secretory granules and prominence of Golgi apparatus and rough-surfaced endoplasmic reticulum. Addition of IFN-gamma (500 U/ml) resulted in marked degeneration with shrinkage of the cell membrane, vacuolation of cytoplasm, swollen mitochondria and presence of lysosomal granules. Co-culturing the thyrocytes with the IFN-gamma and TSH resulted in suppression of the morphological responsiveness to TSH. There was also suppression of TSH-induced TG secretion. However, at 500 U/ml IFN-gamma did not cause lysis of the thyrocytes as estimated by the cellular DNA content. Furthermore, binucleated cells were frequently encountered in those wells that were treated with IFN-gamma for either 2 or 5 days. The findings suggest that IFN-gamma resulted in de-differentiation and degeneration of the thyrocytes, which subsequently regained the growth potential and showed attempts at regeneration. This may explain why most patients with lymphocytic thyroiditis recover from the acute injury and do not suffer from permanent hypothyroidism.

Rat wild-type parathyroid hormone receptor (PTH-R) and mutant PTH-RP132L show the different intracellular localization in vitro

A replacement of proline with leucine at position 132 of the receptor for parathyroid hormone (PTH)/parathyroid hormone-related peptide (PTHrP), i.e., PTH-R, has been discovered in human Blomstrand's lethal chondrodysplasia. As skeletal deformities in this type of chondrodysplasia appear to compromise the receptor binding to its ligands, we examined the possibility that rat PTH-R carrying P132L mutation (PTH-R(P132L)) would result in abnormal intracellular localization. Osteoblastic MC3T3-E1 cells were transfected with expression vectors containing cDNAs encoding either wild-type PTH-R or mutant PTH-R(P132L). The cells expressing the wild-type PTH-R produced a receptor protein with a molecular mass of 66.3 kDa, which localized its immunoreactivity mainly on the cell surfaces. In contrast, the PTH-R(P132L) was hardly detected on the cell surfaces, but accumulated within the rough-surfaced endoplasmic reticulum. Consistent with this localization, the cells expressing the mutant receptor failed to generate cyclic AMP in response to PTH. Furthermore, a remarkably weaker intensity of the 66.3 kDa band compared with the wild-type counterpart suggests that PTH-R(P132L) is prone to degradation in the transfected cells. In summary, these findings indicate that defective transport of PTH-R(P132L) to the cell surface would be a molecular basis for Blomstrand's chondrodysplasia.

Unique Matrix Structure in the Rough Endoplasmic Reticulum Cisternae of Pseudoachondroplasia Chondrocytes

Mutations in cartilage oligomeric matrix protein (COMP) cause two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED/EDM1). Because COMP exists as a homopentamer, only one mutant COMP subunit may result in an abnormal complex that is accumulated in expanded rough endoplasmic reticulum (rER) cisternae, a hallmark of PSACH. Type IX collagen and matrilin-3 (MATN3), also accumulate in the rER cisternae of PSACH chondrocytes, but it is unknown how mutant COMP interacts with these proteins. The studies herein focus on defining the organization of these intracellularly retained proteins using fluorescence deconvolution microscopy. A unique matrix organization was identified in which type II procollagen formed a central core surrounded by a protein network of mutant COMP, type IX collagen, and MATN3. This pattern of matrix organization was found in multiple cisternae from single chondrocytes and in chondrocytes with different COMP mutations, indicating a common pattern of interaction. This suggests that stalling of mutant COMP and an interaction between mutant COMP and type II procollagen are initiating events in the assembly of matrix in the rER, possibly explaining why the material is not readily cleared from the rER. Altogether, these data suggest that mutant COMP initiates and perhaps catalyzes premature intracellular matrix assembly.

Morphological Alterations of Submandibular Glands Caused by Cisplatin in the Rat

Cisplatin is a platinum-containing antineoplastic agent, widely used in the treatment of various malignant neoplasms including head and neck cancer. In this study we examined ultrastructural changes of rat submandibular glands (SMGs) after cisplatin treatment. Male Wistar rats aged 8 weeks were used in the experiments. Cisplatin was injected intraperitoneally into the rats (5 mg/kg/day) for three consecutive days. After 1, 3, 5, and 7 days, the SMGs were removed and observed under an electron microscope. The terminal portion of the SMG is seromucosal. Acinar cells contained a parallel array of rough-surfaced endoplasmic reticulum in the basal cytoplasm, and the apical cytoplasm was filled with homogeneous secretory granules. Vacuolation of cells was observed on the first day after cisplatin treatment. On the third and fifth days, the rough-surfaced endoplasmic reticulum showed an irregular arrangement. Mitochondrial swelling, and the presence of autophagolysosomes was also confirmed. On the seventh day, the damage to organelles began to decrease and the SMG exhibited a tendency towards improvement.

Ossifying Fibromyxoid Tumor: Modified Myoepithelial Cell Tumor? Report of Three Cases with Immunohistochemical and Electron Microscopic Studies

Ossifying fibromyxoid tumors (OFMT) are rare soft tissue tumors of uncertain histogenesis and clinical behavior. Since Enzinger, Weiss, and Liang first described 59 examples in 1989 (Am Surg Pathol. 13:817–827), approximately 150 cases have been reported. Their clinicopathologic features are fairly well characterized and their histogenesis remains unknown. Three examples of soft tissue tumors with typical histopathologic characteristics of OFMT were studied: case 1, a 43-year-old female with a 2.5-cm tumor of the back; case 2, a 56-year-old man with an 8-cm thigh mass; and case 3, an 81-year-old female with a 13.5-cm buttock tumor. For immunohistochemistry, formalin-fixed, paraffin-embedded tissue sections were stained with antibodies against cytokeratin, smooth muscle actin, desmin, vimentin, S-100 protein, EMA, and collagen type IV using standard ABC-peroxidase methods. For electron microscopy, tissue samples fixed in EM-grade buffered formalin were processed according to routine methods. Immunohistochemistry showed that the tumor cells were positive for vimentin and S-100 protein in all 3 cases. Stains for collagen type IV revealed diffusely positive staining in the stroma with a tendency for stronger staining around the cell borders in 2 out of 3 cases. Desmin was positive in one and actin was positive in one other case. By electron microscopy, tumor cells were characterized by centrally located round to oval nuclei with varying amounts of cytoplasm containing scanty cytoplasmic organelles. There were rare profiles of rough-surfaced endoplasmic reticulum (RER) and rare mitochondria with areas of condensed intermediate filaments. No tonofilaments or actin filaments were present. There were multiple short web-like processes, some of which were attached to that of neighboring cells by primitive cell junctions. In all 3 cases, lesional cells showed external lamina (EL), which was abundant in case 1, forming redundant scrolls frequently. In case 2, EL was less prominent and incomplete, and interrupted portions of EL were present only along the periphery of cell columns or nests bordering the stroma. In case 3, which behaved as a malignant tumor, the tumor cells were less differentiated spindle cells with primitive cellular features, and EL was rarely found along the short span of tumor cell borders. In this study, tumor cells in OFMT were polygonal to stellate often with multiple short cytoplasmic processes. The tumor cells were found to form cell clusters attached by primitive intercellular junctions between cytoplasmic processes forming intercellular bridges. The cell borders facing the stroma around cell clusters tended to be flat and had incomplete EL, while no EL was present along the cell borders facing the inner aspect of cell clusters. These ultrastructural findings together with immunophenotypic expression of S-100 protein presented closer resemblance to those of modified myoepithelial cells in pleomorphic adenomas of salivary glands and skin appendages rather than peripheral nerve sheath tumors. The authors conclude that these findings render more support to the hypothesis of myoepithelial histogenesis of OFMT. They also conclude that ultrastructural study not only helps accurate diagnosis, but also may aid in predicting malignant behavior by the degree of deviation from the typical examples of OFMT.

Occurrence of Tubuloreticular Structures and Intracisternal Paracrystalline Inclusions in Endothelial Cells of Tissue from Different Epidemiological Types of Kaposi's Sarcoma

Biopsied tissue specimens from 40 cases of classic, atypical classic, endemic, and AIDS-associated Kaposi's sarcoma (KS) were investigated by electron microscopy. To search for ultrastructural differences between non-AIDS-associated KS and AIDS-associated KS, the occurrence of the following 2 ultrastructural abnormalities of the rough-surfaced endoplasmic reticulum in KS cells was evaluated semi-quantitatively: tubuloreticular structures (TRS) and intracisternal paracrystalline inclusions (IPI). These peculiar structures were found in 23 of the 40 KS cases. Two types of TRS could be distinguished: loose TRS (LTRS) and compact ones (CTRS). LTRS were observed in endothelial cells of tissue from all the different epidemiological types of KS. CTRS were confined to AIDS-associated KS. IPI were present in endothelial tumor cells of only 3 non-AIDS-associated KS cases. The study shows that in cells of KS tissue only CTRS, but not LTRS, are an ultrastructural marker for AIDS-associated KS.

Ultrastructural determination of gingival Langerhans cells in alloxan-induced diabetic rats.

The ultrastructure of Langerhans cells has not been fully investigated in diabetes-associated gingival tissues. The present study was carried out to investigate the ultrastructure of gingival Langerhans cells in alloxan-induced diabetic rats. Gingival biopsies were obtained from 22 diabetic and 18 control rats. Langerhans cells were observed by transmission electron microscopy (TEM) in the basal layers of healthy oral epithelium. On rare occasions, Langerhans cells were found in the suprabasal layers of the oral epithelium. Langerhans cells in the oral epithelium of diabetic rats were seen in the basal and suprabasal layers. Usually, Langerhans cells had clear cytoplasm and convoluted or indented nuclei and few or no specific granules. The clear cytoplasm contained mitochondria, lysosomes and a small number of rough-surfaced endoplasmic reticulum regions, but it lacked tonofilament. Occasionally, centrioles were also observed in the cytoplasm. The membrane of Langerhans cells had no junctional complexes such as desmosomes. In diabetic rats, Langerhans cell precursors were developed into specific granule-bearing cells. Both Langerhans cells and their granules were more frequent in the gingiva of diabetic rats than in the control group. These data suggest that Langerhans cells play an important role in explaining the pathogenesis and development of diabetic gingivitis.

Physiological and Histological Studies on the Effect of Lupine Seeds on the Fish, Clarias lazera Treated with Glucose and Alloxan

Catfish Clarias lazera (C. gariepinus) was used to study the effect of aqueous lupine seed suspension (ALSS) (Lupinus termis) on normal or treated fish with alloxan or glucose after 5, 24 and 4 days. Injection of alloxan was followed by hyperglycemia, hyperlipidemia, hypercholesterolemia, and rise in serum levels of total free amino acids (TFAA), AST and ALT compared with control. In liver, alloxan significantly reduced glycogen and total lipid/triglyceride ratio, while it accumulated lipids and elevated AST and ALT compared with control values. Also, alloxan induced lipid and glycogen depletion in red and white muscles. However, all disturbances in these parameters were restored to normal after ALSS administration. In glucose-treated fish, ALSS significantly increased glycogen content in white and red muscles. Also, glucose plus ALSS treatment increased red muscle contents of TFAA, total lipids and triglycerides. ALSS treatment did not induce any histological changes in liver. Both glucose and alloxan treatments induced damage effect on liver besides, ultrastructural alterations in the liver were observed. Furthermore, histochemical observation revealed a high liver glycogen following repeated glucose doses, while liver glycogen was depleted in response to alloxan injection. Alloxan induced necrosis, mitochondrial damage, few ribosomes on the surface of rough endoplasmic reticulum (rER) with disrupted cisternae in liver cells. Repeated doses of glucose injection for 4 days led to necrosis, clumps of rarefied cytoplasm as well as some cisternae of rER appeared to be devoid of ribosomes. However, most histological and ultrastructural changes in the liver were restored to normal after ALSS administration. In conclusion, it could be suggested that the lupine seeds have a protecting effect against both metabolic disturbances and damaging effect on liver cells in response to repeated doses of glucose or to alloxan treatments.

Thyroid hormone regulation of granular intercalated duct cells in the submandibular glands of female mice.

Intercalated ducts (IDs) in the submandibular glands (SMGs) of mice exhibit a sexual dimorphism, in which a few cells in the IDs of females, but not of males, possess secretory granules. The effects of a hypophysectomy (Hypox) followed by the administration of triiodo- l-thyronine (T3) on such granular intercalated duct (GID) cells in the female gland were histologically examined. Semithin sections stained with Heidenhain's iron hematoxylin revealed that Hypox resulted in the complete disappearance of the GID cells. In Hypox females, electron-microscopy examination of the ID cells whose localization corresponded to that of the GID cells in normal females showed that these cells had a pale, centric nucleus, poorly developed rough-surfaced endoplasmic reticulum (RER) and Golgi apparatus, and no secretory granules. When T3 (1 mg/kg body weight) was given to Hypox female mice every other day for 2 weeks, the GID cells reappeared in most of the ID segments. Electron microscopy revealed that these cells had abundant secretory granules in their apical cytoplasm, a nucleus located near the base of the cell, and layered cisterna of RER and segments of Golgi apparatus in the perinuclear cytoplasm. The localization and distribution of the GID cells in the T3-treated Hypox females were almost the same as those in normal females. Taken together, these results suggest that thyroid hormones upregulate the GID phenotype, and that thyroid hormones are essential for the exocrine activities of GID cells.