Langerhans cells in the lymph node: mirror section and immunoelectron microscopic studies.

Cells immunostained with antibodies against both OKT-6 and S-100 protein were observed only in superficial and hilar lymph nodes draining tissues with predominantly squamous epithelia. In contrast, in mesenteric lymph nodes and the spleen, only S-100 protein-positive, but OKT-6-negative cells were found. We suspect that the S-100 and OKT-6-positive cells might be Langerhans cells (LC) and the S-100-positive, OKT-6-negative cells, interdigitating reticulum cells (IDC). We further postulate that the LC in superficial and hilar lymph nodes might migrate from squamous epithelia, with which contact is required for the formation of Birbeck granules.     

In situ embedding method of cells grown in beem capsules for immunoelectron microscopic studies of oncornaviruses.

A technique of in situ embedding of cells grown in BEEM capsules has been devised for immunoelectron microscopic studies of oncornaviruses. As compared to other immunoelectron microscopic procedures, this technique is less time and reagent-consuming. The quality and specificity of this method were tested on well-characterized mouse mammary tumor virus (type B virus) and murine sarcoma virus (type C virus particles). This method gave good results in labeling of the virus particles with ferritin or peroxidase in the cells of mouse tissue cultures. In an application of this method, peroxidase labeling of type B virus particles was obtained in frozen sections of normal prostatic tissues of C3H/Dm and A/Dm strain mice treated with rabbit antiserum to mouse mammary tumor virus from A/Dm strain mouse milk. These results indicate that this method is useful and reliable for immunoelectron microscopy studies of oncornaviruses in tissue culture cells and also in frozen sections of tissues.     

Ultrastructural and histochemical studies on guard cells

Serial thick sections of guard cells from Vicia faba L., Nicotiana tabacum L., Allium cepa L., Zea mays L. and Beta vulgaris L. were obtained systematically (600–800 nm) and viewed with the transmission electron microscope in an effort to demonstrate the presence or absence of a symplastic transport pathway within the stomatal complex. Eight to ten stomata from each species were examined, and no continuous plasmodesmata were found connecting guard cells to sister guard cells or to adjacent epidermal or subsidiary cells. Continuous plasmodesmata were observed in immature guard cells, but were sealed (truncated) during the development of the mature cell wall. Histochemical stains, phosphotungstic acid and silver methenamine, were used to demonstrate differentiation within the mature guard-cell wall. The structural differentiation of the stomatal apoplastic region is discussed in relation to fanctional specialization. Plasma-membrane elaborations or plasmalemmasomes were identified in the guard cells of Zea, and it is suggested that these structures may function in ion transport.Abbreviations PTA-HCl phosphotungstic acid and hydrochloric acid - SM silver methenamine - UA-LC uranyl acetate and lead citrate     

Light and electron microscopic studies on experimental nocardia-toxicosis in mice

An exotoxin (HS-6) produced by Nocardia otitidiscaviarum isolated from certain lesions of cutaneous nocardiosis of a male 82-year-old patient induced severe injuries in the pancreas, liver, stomach, small intestine, heart, thymus and kidney of male ICR mice. Mice given Nocardia-free preparation of HS-6 at a dose of 1 mg/kg of body weight developed several autophagic vacuoles in the pancreas and liver within 20 min after the i.p. injection. Thereafter, the autophagic vacuoles increased in number and size with time. About 24 hr after the administration of HS-6, the liver showed marked accumulation of fat droplets in the cytoplasm of the hepatocytes. Although they contained abundant autophagic vacuoles in the regions of RER, there were no lipomatoses in the acinar cells of the pancreas, those of the chief cells and smooth muscle cells of the stomach, Paneth cells, goblet cells, smooth muscle cells of the small intestine, and plasma cells in the digestive tract. Biochemical examinations revealed that HS-6 had no significant effect on the protein synthesis of reticulocytes. Inoculation of the Nocardia into the mouse peritoneal cavities caused marked granulomatoses in the pancreas, liver and regional lymph nodes, but did not develop autophagic vacuoles in RER regions of these organs.     

A light microscopic study of the mononuclear cells infiltrating skin homografts in the garter snake, Thamnophis sirtalis (Reptilia: Colubridae)

The rejection of skin homografts in the snake, Thamnophis sirtalis is preceded by an infiltration of mononuclear cells into the graft bed. The initial arrangement of infiltrating cells in perivascular halos suggests that these cells emigrate from the blood stream of the host. A cytological study showed that the vast majority of the cells can be classified as small and mediumsized lymphocytes, monocytes and macrophages. Early stages of infiltration were associated with large proportions of lymphocytes while later stages were characterized by a predominance of macrophages. It was concluded that the mononuclear cells associated with graft rejection include large proportions of lymphocytes and macrophages and not just one kind of lymphoid cell.     

Expression of epithelial membrane antigen on malignant mesothelioma cells. An immunocytochemical and immunoelectron microscopic study

The presence of epithelial membrane antigen (EMA) on malignant mesothelial cells found in pleural and ascitic fluids was demonstrated immunocytochemically using a monoclonal anti-EMA antibody. Serous fluids of 25 patients with malignant mesotheliomas were investigated. In 23 cases, varying numbers of EMA-positive tumor cells were present; in 2 cases, no such cells were found. Immunoelectron microscopy was performed both on Lowicryl-embedded sediments of serous fluids and by application of preembedding techniques using the immunogold method. Expression of EMA by the immunogold method was found selectively on the villi of the malignant mesothelioma cells whereas the nonvillous, flat surfaces were largely EMA-negative. The results indicate that immunoelectron microscopy may offer a useful adjunct in the diagnosis of malignant mesothelioma in serous fluids.     

Immunohistochemical and microscopic studies on giant cells in tuberous sclerosis

Tuberous sclerosis (TSC) is an autosomal dominant disease, caused by mutations in TSC1 or TSC2 genes, encoding hamartin and tuberin, respectively. The clinical picture of the disease is connected with the formation of hamartomas, mainly in the heart, kidneys and the brain. In three types of brain lesions: cortical tubers, subependymal nodules and subependymal giant-cell astrocytoma (SEGA) characteristic, so-called "giant cells" are found. In the present review we summarise immunohistochemical findings of two types of studies performed on giant cells aiming at establishing the expression of hamartin and tuberin level and determining the presence of neuron- or astrocyte-specific markers. Moreover, we support our argument with the summary of ultrastructural research done with the purpose of demonstrating structures characteristic of neural and/or glial cells. We conclude that giant cells in cortical tubers and SEGAs are the same undifferentiated cells that, depending on individual determination, can show neural or glial features.     

Effects of light deprivation on prolactin cells in golden hamsters: an immunoelectron microscopic study.

In the golden hamster light deprivation has been shown to induce gonadal regression and reduction of pituitary and plasma levels of prolactin (PRL). In the present study we examined changes in morphology and population ratios of three types of PRL cells 8 weeks after light deprivation, by means of blinding or exposure of hamsters to continuous darkness. In the pituitary of intact hamsters of either sex, which were entrained to a 14-h light: 10-h dark cycle, Type C cells with large secretory granules were the most numerous and Type A with smaller granules the least. After light deprivation the pituitary was found to contain remarkably atrophic PRL cells and showed a profound change in population ratio of PRL cell types, i.e., Type A cells prevailed over the other two types. Pituitary glands from light-deprived and concurrently pinealectomized hamsters exhibited structures and a population ratio of three types of PRL cells similar to those from intact animals. It is suggested that small-granule-containing PRL cells represent an inactive stage of PRL cells, whereas medium- and large-granule-containing cells are functionally active cells. The atrophy of PRL cells can account for the decreased pituitary level of PRL in light-deprived hamsters reported previously.     

Electron microscopic studies on mouse Leydig cells in vitro

The ultrastructure of cultured Leydig cells isolated from mice testes was studied in the early and late phases of culture. Cells were cultured in Leighton tubes on glass evaporated with carbon and covered with Formvar films. Additionally a histochemical test was carried out in order to evaluate the delta 5, 3 beta-hydroxysteroid dehydrogenase activity of Leydig cells in vitro. Levels of androgen released into the culture medium were measured by radioimmunoassay. Both the histochemical and radioimmunological analyses showed high activity of the enzyme studied and a higher androgen level in the first 4 days of culture. During culture a progressive decrease of the steroidogenic function of Leydig cells in vitro as well as some degenerational changes of the cells were observed. The ultrastructural studies showed the difference between Leydig cells in vitro and in vivo and proved the occurrence of the degenerational modifications of cells in the late phase of culture.     

Ultrastructural studies on plastids of generative and vegetative cells in Liliaceae

Summary The behaviour of plastids and mitochondria during the formation and development of the male gametophyte of Chlorophytum comosum has been investigated using electron microscopy. During first pollen mitosis an intracellular polarization of plastids occurs in that the plastids are clustered in the centre of the microspore. The originating generative cell normally lacks plastids. Only in a small number of microspores have plastids been observed near the dividing nucleus of the microspore and later on in the generative cell. These observations agree with the genetic investigations of Collins (1922) on the mode of plastid inheritance which demonstrated a small amount of biparental plastid inheritance in Chlorophytum. The cytological mechanisms underlying plastid polarization during the first pollen mitosis are discussed.     

Different immunoelectron microscopic locations of progesterone receptor and HSP90 in chick oviduct epithelial cells.

The intracellular locations of the components of the heterooligomeric progesterone receptor (PR), heat-shock protein (hsp90), and the ligand-binding component were studied by immunoelectron microscopy in the chick oviduct, using immunogold double labeling and peroxidase techniques with monoclonal antibodies (MAb) against hsp90 (7D alpha and 4F3) and against PR (PR6 and PR13). PR was located in the nuclei of epithelial cells independently of the presence or absence of ligand. Cells with apically located nuclei were often PR negative. Ten minutes after progesterone administration no apparent change was seen in PR immunoreactivity, but chromatin underwent extensive rearrangement and PR was seen at the margins of the hetero- and euchromatin. The nucleoli did not contain PR. Hsp90 was located in the cytoplasm as aggregates, often inside small vesicles. In the apical part of the cell, hsp90 was located at the Golgi complex. The nuclei contained no detectable amounts of hsp90 except for that in the nucleoli. Ten minutes after progesterone administration the location or immunoreactivity of hsp90 did not alter. Thus, there seems to be a clear difference in the intracellular distribution of PR and hsp90. The epithelium also exhibited some cells with high levels of hsp90 and no or low levels of PR. These results raise the question of whether PR is associated with hsp90 in intact cells.     

Ultrastructural and immunohistochemical studies on the zona-reticularis cells of the adrenal cortex of normal and 3-methylcholanthrene-treated mice

The drug-metabolism activity of adrenocortical cells of normal and 3-methylcholanthrene (MC)-treated ddY mice were examined ultrastructurally and immunohistochemically. Immunoblot analyses performed prior to immunohistochemistry revealed the presence of a protein - possible equivalent to cytochrome P-450 found in the liver microsomes of MC-treated male rats - in the adrenal homogenate of MC-treated female mice. Immunohistochemistry demonstrated the presence of a cytochrome-P-450-like protein in the adrenal-cortical cells (especially in the zona-reticularis cells) of MC-treated female mice; at the same time, a remarkable increase in the amount of SER in these cells was observed by electron microscopy. These findings suggest that cells of the mouse adrenal gland, particularly those of the zona-reticularis, might participate not only in steroid biosynthesis but also in some sort of drug metabolism (detoxication). In addition, there might be a sex-related difference in ddY mice.     

Ultrastructural and immunohistochemical studies on the zona-reticularis cells of the adrenal cortex of normal and 3-methylcholanthrene-treated mice

Summary The drug-metabolism activity of adrenocortical cells of normal and 3-methylcholanthrene (MC)-treated ddY mice were examined ultrastructurally and immunohistochemically. Immunoblot analyses performed prior to immunohistochemistry revealed the presence of a protein — possible equivalent to cytochrome P-450 found in the liver microsomes of MC-treated male rats — in the adrenal homogenate of MC-treated female mice. Immunohistochemistry demonstrated the presence of a cytochrome-P-450-like protein in the adrenal-cortical cells (especially in the zona-reticularis cells) of MC-treated female mice; at the same time, a remarkable increase in the amount of SER in these cells was observed by electron microscopy. These findings suggest that cells of the mouse adrenal gland, particularly those of the zona-reticularis, might participate not only in steroid biosynthesis but also in some sort of drug metabolism (detoxication). In addition, there might be a sex-related difference in ddY mice.Supported by grants from the Ministry of Education, Science and Culture, Japan     

Purification of Drosophila hsp 83 and immunoelectron microscopic localization

Heat-shock protein (hsp) 83 was purified from Drosophila culture cells. Analysis by gel filtration revealed that this hsp exists in a dimeric form under nondenaturing conditions. Monoclonal and polyclonal antibodies produced against this hsp have been used to determine its intracellular localization by indirect immunofluorescence and immunogold electron microscopy in normal cells, after heat shock, during recovery and after a second heat shock. Under normal conditions, hsp 83 is predominantly cytoplasmic. Immunogold labeling reveals that this hsp is associated with vacuole-like structures containing numerous dense bodies. In addition, hsp 83 is detected, albeit at a lower level, in the nucleus where it is found within the network of perichromatin ribonucleoprotein (RNP) fibrils. This distribution changes during heat shock: hsp 83 is then found in increased concentrations at the cell periphery close to the plasma membrane. After a recovery period, hsp 83 appears associated with the nuclear membrane and/or with the neighboring endoplasmic reticulum. Following a second heat shock at 37 degrees C after recovery, a renewed deposition of hsp 83 is observed at the cell periphery. A small population of cells also shows an increased concentration of this protein in the nucleus. This intracellular distribution of hsp 83 is consistent with its reported association with various cellular proteins and suggest that this hsp may be involved in their intracellular transport and/or in the modulation of their activity.