The influence of diet and dimethylhydrazine on the large intestine of vervet monkeys: scanning and transmission electron microscope studies.

The study was designed to identify diet and carcinogen-dependent ultrastructural changes in the epithelium of macroscopically normal colonic mucosa in primates. Seventy adult female vervet monkeys were divided into seven equal treatment groups. Four received a Western high-fat low fibre diet (WD), two a prudent low-fat higher fibre diet (PD) and one a control low-fat high fibre diet (CD). Three groups (2 WD, 1 PD) received dimethylhydrazine intramuscularly at 14 day intervals. After 18 months, monkeys of two groups on the WD were transferred to the PD (WD----PD) and 30 months later all were killed. Mucosae of caecum, colon transversum and rectum were examined by scanning and transmission electron microscopy and showed close similarity to that of humans. Rectal mucosae showed increased surface goblet cell secretory activity, mucin production and microvillar changes related to WD and WD----PD. The enhancing effect of a carcinogen on ultrastructural changes such as cellular pleomorphism, cytoplasmic interbridging, nuclear and nucleolar irregularities and appearance of argentaffin cells in the free surface epithelium were noted predominantly in high-fat treated animals. Such changes observed in the upper part of crypt, orifice and free surface epithelium can be characteristic for precancerous change and could be utilised practically in the detection of precursor lesions of the colon.     

The influence of diet and dimethylhydrazine on the small and large intestine of vervet monkeys

The morphological features of the intestine in monkeys on various diets with and without carcinogen were studied. Seventy adult female vervet monkeys were divided into seven treatment groups. Four groups received a Western high-fat low fibre diet (WD); two a Prudent low-fat higher fibre diet (PD) and one a control low-fat high fibre diet (CD). Three groups (2 WD, I PD) received dimethylhydrazine 10 mg/kg intramuscularly at 14 days intervals. After 18 months, monkeys of two groups on the WD were transferred to the PD and 30 months later all were terminated. Small and large intestine were examined macroscopically, histologically with morphometry, histochemically for acid and neutral, sialo- and sulphomucins and enzyme-histochemically for mucosal gamma-glutamyltranspeptidase (GGT) activity. Large intestines in all other than CD, particularly in WD-treated animals were dilated, thin walled, less corrugated and contained more residual contents. Diverticulosis was found to be mostly associated with WD. Apparently histologically normal colonic mucosa showed changed mucin secretion, predominantly in WD groups, and also GGT activity in all but CD groups. Changes which could be associated with pre-malignancy occurred predominantly but not exclusively in carcinogen treated animals. Within 4 years of feeding to monkeys, diets used by affluent western man caused distinct changes suggestive of the development of intestinal diseases such as megacolon, diverticulosis and cancer. Feeding a prudent diet resulted in only a mild reduction of these signs, whereas they were absent in a usual monkey diet that was much lower in animal products and refined carbohydrates.     

The influence of diet and dimethylhydrazine on the small and large intestine of vervet monkeys.

The morphological features of the intestine in monkeys on various diets with and without carcinogen were studied. Seventy adult female vervet monkeys were divided into seven treatment groups. Four groups received a Western high-fat low fibre diet (WD); two a Prudent low-fat higher fibre diet (PD) and one a control low-fat high fibre diet (CD). Three groups (2 WD, I PD) received dimethylhydrazine 10 mg/kg intramuscularly at 14 days intervals. After 18 months, monkeys of two groups on the WD were transferred to the PD and 30 months later all were terminated. Small and large intestine were examined macroscopically, histologically with morphometry, histochemically for acid and neutral, sialo- and sulphomucins and enzyme-histochemically for mucosal gamma-glutamyltranspeptidase (GGT) activity. Large intestines in all other than CD, particularly in WD-treated animals were dilated, thin walled, less corrugated and contained more residual contents. Diverticulosis was found to be mostly associated with WD. Apparently histologically normal colonic mucosa showed changed mucin secretion, predominantly in WD groups, and also GGT activity in all but CD groups. Changes which could be associated with pre-malignancy occurred predominantly but not exclusively in carcinogen treated animals. Within 4 years of feeding to monkeys, diets used by affluent western man caused distinct changes suggestive of the development of intestinal diseases such as megacolon, diverticulosis and cancer. Feeding a prudent diet resulted in only a mild reduction of these signs, whereas they were absent in a usual monkey diet that was much lower in animal products and refined carbohydrates.     

Basal lamina fenestrations in the human colon: transmission and scanning electron microscope study

Basal lamina at the interface between colonic epithelial cells and the lamina propria was exposed by incubating colonic specimens in 1% boric acid solutions. Examination of this epithelial-stromal interface by scanning electron microscopy (SEM) showed a smooth, slightly undulating basal lamina covering crypts and luminal surfaces. The basal lamina on the luminal surfaces had numerous round or ovoid fenestrations, most measuring 2.5-4.0 microns. These were continuous with channels in the collagen fiber network of the lamina propria. Except very near the surface, no fenestrations were found in the basal lamina lining the crypts. Transmission electron microscopy (TEM) of serial thin sections of colonic mucosa without the epithelial cells removed showed only a few actual basal lamina fenestrations. Rarely, epithelial cell processes extended into the lamina propria through the basal lamina. Most of the fenestrations seen by SEM appeared to correspond spatially by TEM to foci of close contact between the basal lamina and underlying fibroblastic cell processes. At these sites the basal lamina and fibroblastic cell process might be removed along with the overlying epithelial cells during processing with boric acid. These data support functional differences in epithelial-stromal interaction between cell populations lining the luminal surface and those making up the crypt lining and pericryptal fibroblast sheath. The TEM findings demonstrate that the human colonic basal lamina is not absolutely continuous and that the development of basal lamina fenestrations and epithelial cell processes extending into the lamina propria is not pathognomonic of neoplastic transformation and stromal invasion.     

Transmission and scanning electron microscope studies of calcified cartilage resorption

The authors' previous report (Savostin-Asling and Asling, 1973) demonstrated that Meckel's cartilage is a favorable site for study of calcified cartilage resorption. In the present study the ultrastructural features at this resorption front have been examined by transmission and scanning electron microscopes (19-day rat fetus). Multinucleated giant cells (chondroclasts) dominated the erosion front. The many features which they showed in common with osteoclasts included abundant mitochondria, vacuolation, lysosomes, sparsity of roughsurfaced endoplasmic reticulum, and deep infoldings at loci of contact with calcified matrix. Crumbling of matrix (with mineral crystals penetrating between these foldings) and fragmentation of collagen fibrils were also seen. The propensity of chondroclasts for spanning several opened lacunae provided special opportunity to demonstrate cell surface modifications in presence or absence of matrix contact. Ameboid processes extending into lacunae were seen by both transmission and scanning procedures; they were sometimes tipped with a veil of filamentous processes as small as 0.3 μm in diameter. Most hypertrophic chondrocytes, when released from lacunae, appeared to be disintegrating. However, in accord with previous evidence of their possible merger with chondroclasts (in light microscopic studies) there was also evidence for breakdown of cell walls between a chondroclast and a chondrocyte in intimate contact, with possibility of cytoplasmic continuity.     

Thick myofilament mass determination by electron scattering measurements with the scanning transmission electron microscope

Summary An accurate value for mass/length of thick myofilaments is required to establish a limit for the maximum number of myosin molecules per crossbridge repeat. The mass/length of the crossbridge regions of desalted thick myofilaments from insect flight muscle (Lethocerus andMusca) and rabbit psoas has been measured with a computer-linked STEM by comparing the electron scattering signal per unit length of unstained thick filaments with that from TMV particles in the same image. Filament preparation was aided by limited digestion of myofibrils to remove Z bands using calcium-activated factor (CAF) from rabbit skeletal muscle; SDS gels showed that this selective protease spared myosin and tended to spare paramyosin but removed C protein.Lethocerus filaments prepared by the CAF procedure were 20–25% heavier per unit length than those prepared by conventional (simple) shearing, and retained a clear and generally uniform 14.5 nm crossbridge repeat by negative staining.We have expressed mass/length of thick filaments as myosin equivalents (mol. wt 0.470 × 10⁶) per crown (that is, the 14.5 nm insect or 14.3 nm vertebrate repeat along thick filaments). TMV standards, calculated to weigh 0.1304×10⁶ daltons nm^–1 and thus equivalent to 4.02 myosins per 14.5 nm, were uniform to ±3%s.d. for 73 particles after normalizing means for each different image field. After subtracting the known paramyosin content from insect measurements (11% for waterbug, 2% for the housefly), but making no C protein correction to rabbit measurements, the following results were obtained:Lethocerus (all) 4.19±0.50 (243 filaments);Lethocerus (CAF prepns) 4.40±0.44 (145 filaments);Musca (all CAF) 4.14±0.37 (57 filaments); rabbit (all CAF) 2.86±0.34 (75 filaments).These values favour the lowest integral number of myosins per crown among currently competing models of thick filament structure. The rabbit value agrees with several previous estimates, including the STEM measurements of Lamvik, which indicated three rather than four myosins/crown. The insect flight myofilament value of four forces re-evaluation of previous estimates by quantitative gels and quantitative microscopy of whole fibrils which had favoured six myosins/crown.     

Transmission and scanning electron microscope studies of calcified cartilage resorption.

The authors' previous report (Savostin-Asling and Asling, '73) demonstrated that Meckel's carilage is a favorable site for study of calcified cartilage resorption. In the present study the ultrastructural features at this resorption front have been examined by transmission and scanning electron microscopes (19-day rat retus). Multinucleated giant cells chondroclasts) dominated the erosion front. The many features which they showed in common with osteoclasts included abundant mitochondria, vacuolation, lysonsomes, sparsity of rough-sufaced endoplasmic reticulum, and deep infoldings at loci of contact with calcified matrix. Crumbling of matrix (with mineral crystals penetrating between these foldings) and fragmentation of collagen fibrils were also seen. The propensity of chondroclasts for spanning several opened lacunae provided special opportunity to demonstrate cell surface modifications in presence or absence of matrix contact. Amebiod processes extending into lacunae were seen by both transmission and scanning procedures; they were sometimes tipped with a veil of filamentous processes as small as 0.3 mum in diameter. Most hypertrophic chondrocytes. when released from lacunae, appeared to be disintegrating. However, in accord with previous evidence of their possible merger with chondroclasts (in light microscopic studies) there was also evidence for breakdown of cell walls between a chondroclast and a chondrocyte in intimate contact, with possibility of cytoplasmic continuity.     

The formation and final structure of the oocyst wall ofEimeria acervulina: A transmission and scanning electron microscope study

Summary The formation and final structure of the oocyst wall ofEimeria acervulina is described, based on a detailed electron microscope study of the maturing oocysts. After fertilization of the macrogametocyte the wallforming bodies of type I progressively undergo disaggregation into smaller bodies and eventually move into spaces left by the pellicular membranes of the zygote, which simultaneously separate and elevate away from the zygote cytoplasm to form the outer layer of the oocyst wall. A newly formed membrane separates this layer from the cytoplasm. Following the formation of the outer layer, another membrane separates and elevates away from the cytoplasm, and the wall-forming bodies of type II, which by now have migrated to the periphery, move into the spaces and fuse together to form the inner layer of the oocyst wall. A newly formed membrane separates this layer from the cytoplasm. The wall of the young oocyst thus consists of two membrane-bound layers of approximately similar thickness; the outer layer being osmiophilic whilst the inner one is paler. An overlying membrane covers the oocyst. The surface of the oocyst wall was smooth in appearance when viewed with the scanning electron microscope.     

Orientation of the wall of the small intestine for electron microscope studies]

A simple and reliable technique for orientation of small pieces of the intestine is suggested; the technique makes it possible to investigate semi-thin sections under light microscope, and ultrastructural topography of the intestine wall--in electron microscope.     

Transmission electron microscopy on simian immunodeficiency virus-infected cocultures of vervet monkeys

Healthy African green monkeys are the natural reservoirs for certain HIV-related SIVs. More research is now focused on these nonhuman primates that are asymptomatic, so as to answer questions of origins, pathogenesis and therapy with respect to HIV in man. The present study involves the isolation and subsequent co-cultivation of SIV variants from two healthy vervet monkeys (Cercopithecus aethiops pygerythrus). Western Blots (New LAV Blot 1 and New LAV Blot 2, Pasteur) revealed sero cross-reactivity of each monkey to major HIV-1 and HIV-2 antigens. Freshly isolated peripheral blood mononuclear cells of each monkey were co-cultivated with the CEMss and M4C8 T-cell lines. The cocultures were incubated in CO2 at 37 degrees C for 3-4 days, before refeeding with RPMI 1640, phytohaaemagglutinin and interleukin-2. Cytopathic effects in the cocultures were observed 14 days post-infection, with syncytia and enlarged, granular cells being predominant in both of the cell-lines used. The presence and morphology of viral-like particles were observed by transmission electron microscopy. Immunocytochemistry and in situ hybridization may help in characterization of the particles, as well as aid in determining localization and concentration in vitro.     

Apoptosis in mouse primordial germ cells: a study by transmission and scanning electron microscope

A detailed study of the death in vitro of mouse primordial germ cell (PGCs) by means of transmission and scanning electron microscopy is reported. The results show that after 4–5 h of culture 15–20% PGCs assume the typical morphological features of apoptotic cells, including chromatin condensation in dense masses under the nuclear membrane, compaction of the cytoplasm, crowding of organelles and surface protuberances. Cells then break up into discrete fragments (apoptotic bodies) which eventually degenerate by secondary necrosis. It is possible that apoptosis plays a biologically useful role in avoiding uncontrolled PGC proliferation and in eliminating misplaced germ cells whose survivial might be harmful to the animal.     

Development of the pigeon bursa of Fabricius. A scanning and transmission electron microscope study

The development of the pigeon bursa of Fabricius was investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Particularly SEM emphasized that the bursa during development progressively undergoes hypertrophia and hyperplasia of lobules constituting the plicae. Moreover modifications of surface epithelium were observed. During early days of development after hatching, epithelium showed evenly distributed microvilli which become shorter and shorter and also unevenly distributed with aging. In addition TEM allowed us to state that the bursa of Fabricius in pigeons, during development, undergoes morphological modifications among which one of the most remarkable is the gradual and continuous increasing of lymphocytes. Another one, as it was already observed in chickens (Frazier 1974), consists in the contemporaneous but independent development of cortex and medulla, even if we observed undifferentiated epithelial cells moving from medulla to cortex and a migration of lymphocytes and mesenchymal cells from cortex to medulla (Tar et al. 1958; Ackerman et al. 1964; Naukkarinen et al. 1978).     

The fragile X: a scanning electron microscope study.

Scanning electron microscopy (SEM) has been used to study the fragile X chromosome. The fragile site appears as an isochromatid gap in the majority of cases, confirming light microscope (LM) observations. SEM has allowed a more precise location of the fragile site to the Xq27 . 3 region.     

CSF-contacting pinealocytes in the pineal recess of the Mongolian gerbil: A correlative scanning and transmission electron microscope study

The pineal recess of the Mongolian gerbil was studied using correlative scanning and transmission electron microscopy. The surface of the pineal recess can be subdivided into three distinct zones: (1) central, (2) transitional, and (3) peripheral. In the gerbil, the deep pineal gland is located deep to the central and transitional zones. The ependyma of the peripheral zone is densely ciliated and resembles that of the main ventricular lining. Ependymal cells of the transitional zone are sparsely ciliated but possess numerous microvilli on their apical surfaces. Supraependymal neurons were identified in the transitional zones. These cells appear to make a synaptic-like contact with the underlying ependymal cells. Of the three zones, the central zone demonstrated the greatest amount of morphological variability. Although a number of supraependymal structures could be identified in the central zone, the most remarkable feature was the presence of protruding cells that possessed no significant surface features Employing correlative transmission electron microscopy, the protruding cells were shown to be CSF-contacting pinealocytes. The number of CSF-contacting pinealocytes present in the central zone varied from one cell to large clusters that covered the entire zone. The results of this investigation demonstrate the presence of a direct contact and the potential for interaction between the deep pineal gland and the CSF of the pineal recess in the gerbil.     

Differential diagnosis between sclerosing adenosis and tubular carcinoma of the breast under transmission and scanning electron microscope

The tubular carcinoma of the breast is an uncommon histological subtype of invasive breast cancer, which is generally associated with an excellent prognosis. Previous studies have demonstrated that this well differentiated variant is linked with a low incidence of lymph node involvement, a low rate of local recurrence and a high overall survival rate when compared to standard invasive ductal carcinoma. Due to its favorable prognosis, some studies have proposed that a diagnosis of tubular carcinoma might warrant less aggressive surgical or adjuvant treatment. Histologically, tubular carcinoma may mimic sclerosing adenoma or bluntduct adenosis. Its ductal nature appears well confirmed by the few ultrastructural studies of this mammary cancer. Tubular carcinoma should also be distinguished from microglandular adenosis, an uncommon form of sclerosing adenosis. The aim of this study is to prove that the ultrastructure results can give the correct diagnosis between tubular carcinoma and sclerosing adenosis.     

Intrapulmonary airway morphology in three species of monkeys: A correlated scanning and transmission electron microscopic study

Intrapulmonary airways were studied in rhesus (Macaca mulatta), stumptail (Macaca arctoides), and bonnet (Macaca radiata) monkeys by correlated scanning and transmission electron microscopy. Lobar, segmental, and subsegmental bronchi in all three macaques were lined by pseudostratified columnar epithelium composed primarily of ciliated cells, mucous cells, and basal cells. Neuronal processes and cells containing dense-core vesicles were also observed. Terminal bronchioles in rhesus and stumptail monkeys were short and only developed to a single generation. Terminal bronchioles were moderately longer in bonnet monkeys and were occasionally developed to two generations. Terminal bronchioles in bonnet and stumptail monkeys were lined by ciliated pseudostratified columnar epithelium which included nonciliated bronchiolar epithelial (Clara) cells. The arrangement of epithelium in terminal bronchioles differed slightly in rhesus monkeys. All three species had long respiratory bronchioles. They were lined by simple, nonciliated cuboidal and squamous epithelium which usually did not contain secretory droplets. Capillaries were often observed immediately below the luminal epithelium. Cuboidal cells containing dense-core vesicles were a rare component of the epithelium of respiratory bronchioles in stumptail monkeys. Alveolar ducts were lined by an epithelium composed of type I and type II cells. The results of this study indicate that there is general similarity in the mucosal structure of bronchi and respiratory bronchioles between macaques and man but that there are differences in the number of generations and epithelial lining of terminal bronchioles.     

The development of the chicken small intestine: a scanning electron microscopy study

The surface pattern of the small intestine of the chicken was studied using SEM in stages ranging from 11th day of foetal development to 60 days of post-natal life. The definite villi of the small intestine were preceded by the development of the previllous ridges. The villi were finger like and of unequal length during incubation. After hatching, gradually, the villi were longer, well formed with furrows along their sides. Respectively, the crypts, being present at late incubation, increased with age. Columnar epithelial cells with dense microvilli lined the luminal surface of the intestine with obvious goblet cells openings among them.