Metamorphosis of the Drosophila visceral musculature and its role in intestinal morphogenesis and stem cell formation.

The visceral musculature of the Drosophila intestine plays important roles in digestion as well as development. Detailed studies investigating the embryonic development of the visceral muscle exist; comparatively little is known about postembryonic development and metamorphosis of this tissue. In this study we have combined the use of specific markers with electron microscopy to follow the formation of the adult visceral musculature and its involvement in gut development during metamorphosis. Unlike the adult somatic musculature, which is derived from a pool of undifferentiated myoblasts, the visceral musculature of the adult is a direct descendant of the larval fibers, as shown by activating a lineage tracing construct in the larval muscle and obtaining labeled visceral fibers in the adult. However, visceral muscles undergo a phase of remodeling that coincides with the metamorphosis of the intestinal epithelium. During the first day following puparium formation, both circular and longitudinal syncytial fibers dedifferentiate, losing their myofibrils and extracellular matrix, and dissociating into mononuclear cells ("secondary myoblasts"). Towards the end of the second day, this process is reversed, and between 48 and 72h after puparium formation, a structurally fully differentiated adult muscle layer has formed. We could not obtain evidence that cells apart from the dedifferentiated larval visceral muscle contributed to the adult muscle, nor does it appear that the number of adult fibers (or nuclei per fiber) is increased over that of the larva by proliferation. In contrast to the musculature, the intestinal epithelium is completely renewed during metamorphosis. The adult midgut epithelium rapidly expands over the larval layer during the first few hours after puparium formation; in case of the hindgut, replacement takes longer, and proceeds by the gradual caudad extension of a proliferating growth zone, the hindgut proliferation zone (HPZ). The subsequent elongation of the hindgut and midgut, as well as the establishment of a population of intestinal stem cells active in the adult midgut and hindgut, requires the presence of the visceral muscle layer, based on the finding that ablation of this layer causes a severe disruption of both processes.

Critical roles of type III phosphatidylinositol phosphate kinase in murine embryonic visceral endoderm and adult intestine.

The metabolism of membrane phosphoinositides is critical for a variety of cellular processes. Phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P(2)] controls multiple steps of the intracellular membrane trafficking system in both yeast and mammalian cells. However, other than in neuronal tissues, little is known about the physiological functions of PtdIns(3,5)P(2) in mammals. Here, we provide genetic evidence that type III phosphatidylinositol phosphate kinase (PIPKIII), which produces PtdIns(3,5)P(2), is essential for the functions of polarized epithelial cells. PIPKIII-null mouse embryos die by embryonic day 8.5 because of a failure of the visceral endoderm to supply the epiblast with maternal nutrients. Similarly, although intestine-specific PIPKIII-deficient mice are born, they fail to thrive and eventually die of malnutrition. At the mechanistic level, we show that PIPKIII regulates the trafficking of proteins to a cell's apical membrane domain. Importantly, mice with intestine-specific deletion of PIPKIII exhibit diarrhea and bloody stool, and their gut epithelial layers show inflammation and fibrosis, making our mutants an improved model for inflammatory bowel diseases. In summary, our data demonstrate that PIPKIII is required for the structural and functional integrity of two different types of polarized epithelial cells and suggest that PtdIns(3,5)P(2) metabolism is an unexpected and critical link between membrane trafficking in intestinal epithelial cells and the pathogenesis of inflammatory bowel disease.

Development of the inverted visceral yolk sac in three species of caviids (Rodentia, Caviomorpha, Caviidae).

Guinea pig related rodents possess numerous derived placental characters. We attempt to identify diversity within the visceral yolk sac and its association with the chorioallantoic placenta in three species of caviids, two of them possessing a capsule formed by the decidua that covers the chorioallantoic placenta. The results verify that in early pregnancy all three species have an inverted yolk sac placenta. In advanced pregnancy the species differ: Galea spixii, as representative without a capsule, bear a yolk sac in apposition to the chorioallantoic placenta with signs of exchange activity until term. Galea is similar to other caviomorphs in this respect. In Dasyprocta leporina and Cuniculus paca, the representatives possessing a capsule, the yolk sac endoderm lacks signs of substance exchange. Evidently, the presence of a capsule prevents such an interaction. The variations established here must be considered if animal models for human placentation are required which have restricted access to the chorioallantoic placenta from the outside.

[Pineal gland and extrapineal melatonin in visceral organs during natural human aging].

In order to define the functional morphology of the pineal gland (epiphysis) and to reveal extrapineal sources of melatonin (MT) during human aging, biopsy samples obtained from 175 male persons aged 16 to 84 were examined. The dynamics of MT-containing cells in the stomach, intestine, bronchi, prostate and the non-endocrinal cells of the adrenals were described.

Mitochondria in smooth muscle cells of viscera.

The spatial density of mitochondria was studied by thin-section electron microscopy in smooth muscles of bladder, iris and gut in mice, rats, guinea-pigs and sheep. Morphometric data included areas of muscle cell profiles (~6,000 muscle cells were measured) and areas of their mitochondria (more than three times as many). The visual method delivers accurate estimates of the extent of the chondrioma (the ensemble of mitochondria in a cell), measuring all and only the mitochondria in each muscle cell and no other cells. The digital records obtained can be used again for checks and new searches. Spatial density of mitochondria varies between about 2 and 10% in different muscles in different species. In contrast, there is consistency of mitochondrial density within a given muscle in a given species. For each muscle in each species there is a characteristic mitochondrial density with modest variation between experiments. On the basis of data from serial sections in the rat detrusor muscle, mitochondrial density varies very little between the muscle cells, each cell having a value close to that for the whole muscle. Mitochondrial density is different in a given muscle, e.g., ileal circular muscle, from the four mammalian species, with highest values in mouse and lowest in sheep; in mice the mitochondrial density is nearly three time higher that in sheep. In a given species there are characteristic variations between different muscles. For example, the bladder detrusor muscle has markedly fewer mitochondria than the ileum, and the iris has markedly more.

Topographical significance of membrane skeletal component protein 4.1 B in mammalian organs.

The polarized architecture of epithelial cells is a fundamental determinant of cell structures and functions. Both formation and orientation of proper epithelial polarity are needed for cell-cell or cell-matrix adhesion, signal transduction and cytoskeletal interactions of multimolecular complexes at apical, lateral and basal cell membranes. These cell membrane domains are usually segregated by some junctional complexes. Recent molecular genetic studies on the anchor structure between myelin sheaths and axons have indicated the specific molecular organization for polarization of axolemma and the myelin sheaths at paranodes, termed 'septate-like junctions'. It was also speculated that other mammalian organs may use a similar junctional system. The protein 4.1 B was originally found to be localized in paranodes and juxtaparanodes of myelinated nerve fibers. Our recent immunohistochemical studies on protein 4.1B have indicated its significance for the cell-cell and/or cell-matrix adhesion in various rodent organs. The protein 4.1 family of proteins have been supposed to possess variable molecular domains relating to cell adhesion, ion balance, receptor responses and signal transduction. Therefore, more precise studies on the molecular structure and the functional domains of protein 4.1B, as well as on its changes under physiological and pathological conditions, may provide a clue for organogenesis in various mammalian organs.

Cellular localization of enzymatically active thrombin in intact human tissues by hirudin binding.

Cellular sites of coagulation activation within complex, intact tissues have been studied by immunohistochemical techniques. Hirudin, a specific and high affinity inhibitor of the active site of thrombin, together with antibody to hirudin were applied to sections of AMeX-fixed specimens of normal lung, kidney, placenta, freshly incised skin and unperturbed skin obtained at fresh autopsy; to rheumatoid synovial tissue; and to malignant tissue from a variety of tumor types. Staining for thrombin was observed selectively on pulmonary alveolar, rheumatoid synovial, and placental macrophages that express an intact extrinsic coagulation pathway. Staining was also observed restricted to the endothelium of capillaries in freshly incised skin but not in either unperturbed skin or in aged incisions. Staining of tumor cell bodies was observed in small cell carcinoma of the lung, renal cell carcinoma, and malignant melanoma tissues that we found previously to show tumor cell-associated procoagulant activity. This staining occurred commonly on cells within the tumor mass that were distant from stromal fibrinogen/fibrin. By contrast, tumor-associated macrophage but not tumor cell staining was seen in adenocarcinoma and squamous cell carcinoma of the lung, and little or no staining was seen colon cancer tissue. Negative controls in which either the hirudin probe or its antibody were omitted failed to show staining. These results are in accord with previous findings and suggest that such techniques may be useful for studying the cellular sites of thrombin generation in intact tissues. We postulate that administration of potent and specific thrombin antagonists, such as hirudin, to patients with relevant tumor types might be followed by homing of hirudin to tumor cells in vivo so that effects of local thrombin generation on malignant progression can be determined.

Contraction bands in visceral and vascular smooth muscle.

Smooth muscle contraction bands (SMCBs) have been described in the gastrointestinal tract, subsequent to acute ischemia, and in the coronary arteries of animals and individuals with a sudden death; in these circumstances SMCBs have been postulated to serve as a premortem marker, and suggested as diagnostically useful. The present investigation was undertaken to determine whether the presence of SMCBs could be correlated with a premortem clinical condition. Retrospectively, the routinely prepared histological sections from 76 autopsy and 93 surgical cases were screened semiquantitatively for the presence of SMCBs. The autopsy sections examined included the gastrointestinal tract, the prostate, and the coronary arteries, as well as all other smooth muscle-containing tissues; the surgical specimens included: coronary artery endarterectomies; saphenous vein bypass grafts; temporal artery biopsies; prostatic curettings; colectomies; varicose veins; leiomyomas of uterus, bowel, and skin; and, leiomyosarcomas. The clinical and pathology reports were reviewed for patient demographics, major clinical diagnoses, presence of shock, details of any resuscitation attempts, time interval to postmortem, and the cause of death. SMCBs were evident in 100% of the gastrointestinal and prostate, and in 96% of the coronary artery autopsy sections examined. All surgical specimens were positive for SMCBs, the exceptions being leiomyomas (positive in 13 of 22; 60%) and leiomyosarcomas (4 of 5; 80%); SMCBs in surgical specimens were less prominent when compared with those observed in autopsy tissue. No correlation was found between the presence of SMCBs and any clinical or demographic parameter assessed, because of the virtual universal occurrence of the SMCBs. The presence of less distinct SMCBs in surgical specimens may very well be artifactual, akin to myocardial and skeletal muscle contraction bands. The observation that SMCBs at autopsy are virtually ubiquitous suggests that they are best considered an agonal phenomenon, and a nonspecific pathological finding.

Sulfatide storage in visceral organs of arylsulfatase A-deficient mice.

The inherited deficiency of arylsulfatase A (ASA) in humans causes lysosomal accumulation of sulfatides in visceral organs and in the nervous system and leads to wide-spread demyelination (metachromatic leukodystrophy, MLD). ASA-deficient mice have previously been generated by means of targeted gene disruption. In the present study, visceral organs of ASA-deficient mice were investigated. A simple technique for the histochemical detection of accumulated sulfatides was elaborated using pre-embedding staining with alcian blue. The gall bladder, intrahepatic bile ducts, exocrine pancreatic ducts, respiratory epithelium and, with low degree, testicular Sertoli cells, showed sulfolipid storage. The storage pattern in the kidney will be described in a separate publication. Hepatocytes, pancreatic islets, adrenal glands, and gastric epithelium were unaffected. Ultrastructurally, the intralysosomal storage material displayed parallel and concentric lamellar patterns. Apart from some differences, the topographic distribution of the sulfatide storage resembled that in human MLD. In addition to being an animal model of the human disease, the ASA-deficient mouse may be useful for investigating the cell biology of sulfolipids in visceral organs.

Ultrastructural changes of tissues produced by inhalation of thinner in rats.

Thinner is a substance that is used for industrial purposes and for drug abuse; addiction is of young people (average age, 7.5 years). Although the health problem of voluntary or nonvoluntary solvent sniffing is important, great attention has been paid to the epidemiology and pharmacology of paint thinner or industrial solvents inhalation, but studies at the morphological and biochemical level are scarce. This work describes the morphological changes in the lung, liver, kidney, adrenal glands, and central nervous system induced by short- (up to 4 weeks) and long-term (up to 14 weeks) periods of thinner inhalation in rats.

A combined electron microscopic investigation of the peritoneal mesothelium in the rat.

Visceral and parietal peritoneum of adult Wistar rats was studied by means of transmission and scanning electron microscopy. The structure of the peritoneum follows a general plan: mesothelium, basal lamina, and submesothelial connective tissue layer. Two basic types of mesothelial cells are described: flat and high (cubic), as well as transitional forms. A regularity of distribution of these cells in the visceral and parietal peritoneal sheets, and in the cover of individual organs and regions is described. A functional characterization of the different types of mesothelial cells is attempted, based on the differences of their cytoplasmic organization. The involvement of the mesothelium in the homeostasis in the peritoneal cavity is discussed.

[Electron microscopic observation of the effects of Rhodiola kirilowii (Regel.) Maxim. in preventing damage of the rat viscera by a hypoxic high altitude environment].

This paper has shown that the pathologic damages done to rat's viscera due to hypoxic environment of altitude can be reduced significantly by oral administrations of Shengmaiyin, Danshen-Chuanxiong mixture and Rhodiola kirilowii. Shengmaiyin that maintains interior substances in the plate layer bodies proves more effective than Danshen-Chuanxiong mixture, while the latter excels in preventing capillary contraction, thus improving blood circulation. Rhodiola kirilowii has the effects of both Shengmaiyin and Danshen-Chuanxiong mixtures.

[The morphological changes in the internal organs in hemochromatosis]. / Morfologicheskie izmeneniia vnutrennikh organov pri gemokhromatoze.

Visceral changes were studied by histological and electron-microscopic methods in cadavers of 18 subjects dead from hemochromatosis. Pronounced visceral changes in all cases represented a characteristic tetrad of signs: bronze-colored skin, pigmentary cirrhosis of the liver, involvement of the pancreas, and cardiomyopathy. In forensic medical practice hemochromatosis can be found in subjects who were probably genetically predisposed to it and, as a rule, had a history of alcohol abuse. Among the numerous complications of the disease, the most incident are cardiac pathology (dilatation cardiomyopathy) and diabetes mellitus with concomitant intoxications caused by various inflammations.

Electron microscopy of the morphological changes in rat viscera during experimental hyperthermic shock.

Hyperthermic shock is a thermoregulatory disorder that affects living organisms that are acutely or chronically exposed to high temperatures or when performing intense physical activity in a hot environment. In this paper, we will show the changes embodied in hyperthermic shock caused by multiple injuries to vital organs in Wistar rats that were suddenly exposed to high temperatures of up to 410 for about 10-15 minutes, their central temperature rising above 40.60C. This process resulted in multiple injuries of the vital organs, evidenced by electron microscopy. In addition, this suggested that most changes caused by hyperthermic shock are incompatible with life.

Experimental analysis of the transdifferentiation of visceral to parietal endoderm in the mouse.

The visceral endoderm (VE) of isolated extraembryonic regions (ExEmbs) of 7 days postcoitum (dpc) prestreak mouse conceptuses have been shown to convert readily to parietal endoderm (PE). The present study addresses the following three unanswered questions. On what does conversion depend, how rapidly does it occur, and is it an enduring general property of a residual small population of relatively immature cells? In situ hybridization reveals that change in cell state occurs within 2 days of culture. Deprivation of the mesoderm also promotes it in later ExEmbs. Conversely, the conversion to PE in isolated 7 dpc ExEmbs is suppressed by grafting 8 dpc or 9 dpc mesoderm. Hence, the conversion provides an example of transdifferentiation that is promoted by the absence of extraembryonic mesoderm. The presence of mesoderm seems to be necessary to enable the VE to grow rather than convert to PE, as occurs if it retains contact with the extraembryonic ectoderm.

Mice with Ppt1Deltaex4 mutation replicate the INCL phenotype and show an inflammation-associated loss of interneurons.

Infantile Neuronal Ceroid Lipofuscinosis (INCL) results from mutations in the palmitoyl protein thioesterase (PPT1, CLN1) gene and is characterized by dramatic death of cortical neurons. We generated Ppt1Deltaex4 mice by a targeted deletion of exon 4 of the mouse Ppt1 gene. Similar to the clinical phenotype, the homozygous mutants show loss of vision from the age of 8 weeks, seizures after 4 months and paralysis of hind limbs at the age of 5 months. Autopsy revealed a dramatic loss of brain mass and histopathology demonstrated accumulation of autofluorescent granular osmiophilic deposits (GRODS), both characteristic of INCL. At 6 months, the homozygous Ppt1Deltaex4 mice showed a prominent loss of GABAergic interneurons in several brain areas. The transcript profiles of wild-type and mutant mouse brains revealed that most prominent alterations involved parts of the immune response, implicating alterations similar to those of the aging brain and neurodegeneration. These findings make the Ppt1Deltaex4 mouse an interesting model for the inflammation-associated death of interneurons.

Generalised nuclear and cytoplasmic inclusion disease: a rare case investigated by microscopy and immunohistochemistry.

A Caucasian female who was noted to be mildly microcephalic at birth was diagnosed as having cerebral palsy at the age of 1 year. Her development was delayed and she never walked or talked. She appeared relatively stable neurologically until the age of 17 years when she had an illness with fever thought to be due to a virus. She was noted to deteriorate from this time on until her death at the age of 19 years. Autopsy revealed intranuclear and cytoplasmic inclusions wide-spread throughout the brain and visceral organs. There was no evidence of inflammation. Immunohistochemistry revealed strong immunoreactivity for tau protein and neurofilament protein. Electron microscopy revealed the inclusions to be composed of homogeneous finely granular material. Scattered within the granular material in the cytoplasmic bodies were crystalline structures with a honeycomb appearance. The possibility of these changes representing an old viral infection or a primary metabolic disorder are discussed.

[Intranuclear inclusions in the cells of different tissues of the aging rat]. / Vnutriiadernye vkliucheniia v kletkakh razlichnykh tkanei u krys pri starenii.

Ultrastructure of neuronal and glial nuclei has been studied in various parts of the CNS, in parenchymatous cells of internal organs, in endotheliocytes and pericytes of their blood capillaries in intact rats--mature (6-8-month-old) and old (26-28-month-old), as well as at certain experimental influences. In all the cellular populations studied (most often in neurons), various in their structure, intranuclear inclusions (INI) have been revealed, that are considered as five main types. The number of INI increases sharply at ageing, that is especially noticeable under experimental conditions. Some INI are situated in morphologically preserved, actively working cells, being normal components of the nucleus, others--reflect profound rearrangements of nuclear proteins, disturbances in lipid metabolism up to irreversible destructive processes in the nucleus.

A scanning electron microscopy morphometric study of the rabbit peritoneal surface.

Rabbit peritoneum was studied by SEM to obtain information and statistically meaningful morphometric data of different sites of visceral and parietal peritoneum and to verify the existence of "stomata." Samples were fixed by intraperitoneal infusion of glutaraldehyde, and were photographed by SEM under standard conditions. Morphometric data were obtained by Kontron MOP Videoplan. Variable cell surface patterns were present even within limited areas; however, "stomata" were not observed. The heterogeneity of data obtained can be related to the dynamism of mesothelial cell activity and to the different motilities of the underlying organs.

Crystalline glomerular inclusions in multiple myeloma.

Prominent crystalline inclusions were noted in the glomeruli of a 57-year-old man with a 6-month history of swelling and pain in the hands, slight proteinuria, and elevated serum creatinine and BUN. The crystalline inclusions were most prominent in the visceral epithelium but were also noted in endothelial and mesangial cells, in the parietal epithelium, and in the epithelial cells of the proximal tubules. On electron microscopy the crystalline structures were of various geometric shapes but had no definite substructure. Immunofluorescence was negative. The patient was considered to have a hitherto undescribed metabolic disease. Several months later the patient underwent an operation for carpal tunnel syndrome and amyloid deposits, crystalline inclusions similar to those noted in the kidney were observed in the synovial tissue. Shortly after this the patient was found to have multiple myeloma of IgG, kappa type with Bence Jones proteinuria. Lymphoplasmacytic cells in the bone marrow contained the same crystalline inclusions noted in the kidney and synovium. This case therefore seems to represent a new and very rare form of glomerular involvement in multiple myeloma.