Journal of Histochemistry & Cytochemistry

Electrocyte membranes of Electrophorus electricus exhibit high ATPase activity, as demonstrated by cytochemical and biochemical techniques. This activity is visualized as electron-dense deposits in electron micrographs, and appears to be localized only at the innervated face of the electrocyte. ATP hydrolysis can be detected cytochemically or biochemically only in the presence of calcium or magnesium. The effects of Ca or Mg on ATPase activity can be described by Michaelis-like functions with similar apparent Km values for Ca and Mg (0.41 mM and 0.23 mM, respectively). Vmax, however, is fivefold higher in the presence of Mg. The effects of the two cations are not additive, and pH dependence of ATP hydrolysis is identical in the presence of Ca or Mg (maximal at pH 8-9). Therefore, it can be concluded that Ca and Mg activate the same enzyme, the differences in Vmax being attributable to influences in kcat.

A variety of heparan sulfate proteoglycans (HSPG) have been identified on cell surfaces and in basement membrane (BM). To more fully characterize HSPG in human skin BM, we used two monoclonal antibodies (MAb) directed against epitopes of the core protein of a high molecular weight HSPG isolated from murine EHS tumor. Indirect immunofluorescence revealed linear distribution of HSPG within all skin BM, and within BM of all other human organs investigated. In a study of the ontogeny of HSPG in human skin BM, HSPG was detectable as early as 54 gestational days, comparable with other ubiquitous BM components, such as laminin and type IV collagen. Immunoelectron microscopy on adult skin and neonatal foreskin showed staining primarily within the lamina densa (LD) and sub-lamina densa regions of the dermoepidermal junction (DEJ) and vascular BM. In neonatal foreskin, additional staining was noted of basilar cytoplasmic membranes of keratinocytes, endothelial cells, and pericytes. We conclude that the core protein of a high molecular weight HSPG is ubiquitous in human BM, appears in fetal skin on or before 54 days, and is present primarily in the regions of the LD and sub-LD.

Ca++-ATPase plays an important role in regulation of the intracellular Ca++ concentration. Biochemical studies of brain have demonstrated that Ca++-ATPase co-purifies with synaptosomes, with synaptic plasma membrane and synaptic vesicle fractions. To better understand the role of this enzyme in normal brain function, we used an electron microscopic (EM) cytochemical method to determine the localization of Ca++-ATPase in rat brain. Reaction product occurred along cytoplasmic membranes. Specific areas of increased reaction product were seen at many but not all post-synaptic densities. Intracellular Ca++-ATPase reaction product was associated with all synaptic vesicles examined and with the Golgi and smooth endoplasmic reticulum (SER). Unlike the situation in peripheral nerve, Ca++-ATPase at the node of Ranvier in the CNS localized preferentially to the nodal axolemma. The localization of Ca++-ATPase at synaptic vesicles agrees with the biochemical evidence for its localization and with the cytochemical evidence for Ca++-ATPase sequestration in those vesicles. The restricted localization at postsynaptic densities suggests that it may be involved in extrusion of Ca++ at synapses where neurotransmitter release causes Ca++ influx.

The exine of birch pollen was examined by scanning and transmission electron microscopy in the native state and after fixation in different aqueous fixatives: glutaraldehyde + OsO4; glutaraldehyde + cetylpyridinium chloride (CPC) + OsO4; glutaraldehyde + cuprolinic blue (CB); and periodate + lysine + paraformaldehyde (PLP). The native pollen exine showed a thin (3-5-nm) border of electron-dense material lining the tectum and electron-dense material within microchannels and bacula cavities. Fixation with the addition of CPC resulted in a voluminous surface coat surrounding the pollen grain, but empty microchannels and bacula cavities. After fixation with the addition of CB, there was a thin surface coat, whereas microchannels and bacula cavities were partially filled with electron-dense material. The other fixatives led to empty microchannels and bacula cavities. There was no surface coat on the pollen grain. However, after all fixation procedures, a thin electron-dense border of the tectum remained visible. Concerning the electron-dense material filling microchannels and bacula cavities in the native pollen grain, the results obtained in the present study suggest that it is either completely lost (after conventional and PLP fixation) or, after fixation with a precipitating additive, partially (CB) or completely (CPC) solubilized and precipitated on the surface of the pollen grain as a surface coat.

A panel of biotinylated (neo)glycoproteins was used for specific detection of endogenous sugar receptors, especially lectins, in formaldehyde-fixed, paraffin-embedded muscle biopsy specimens from human deltoid, quadriceps, and biceps muscles, tibial and quadriceps muscles of rat, and bovine masseter muscle. The glycohistochemical probes used consisted of conjugates of a labeled, histochemically inert carrier protein and various covalently linked, histochemically crucial sugar moieties. Specific binding of alpha-L-fucoside, beta-D-galactoside, beta-D-xyloside, and alpha-D-mannoside to muscle sections was detected, showing no species-specific differences. The presence of receptors for the N-acetylated sugars in natural glycoconjugates, and for sugars with a phosphate group, i.e., mannose-6-phosphate and galactose-6-phosphate, was demonstrated glycohistochemically. However, these binding specificities revealed species-specific differences, e.g., the absence of N-acetyl-D-galactosamine-specific receptors or galactose-6-phosphate-specific receptors in rat muscle. Other charged sugars included glucuronic acid and sialic acid, which bound only to ox and rat muscle or failed to reveal their respective receptors in all types of muscle investigated. This different extent of staining with anionic probes served as a further control to ascertain carbohydrate binding specificity. Positive glycohistochemical reaction developed within sarcomeres only at the level of A-bands. Granular staining was observed in the sarcoplasm among the myofibrils and also in the subsarcolemmal regions. Differences in expression of glycohistochemically detectable sugar receptors were noted between type 1, type 2A, and type 2B fibers. The molecular properties of one type of glycohistochemically detectable sugar receptor were inferred both immunohistochemically and biochemically. An antiserum against an endogenous beta-galactoside-specific lectin from muscle tissue localized this lectin within sections consistently similar to (neo)glycoproteins, detecting beta-galactoside-specific receptor(s). This similarity of binding patterns strongly supports the assumption that (neo)glycoproteins with beta-galactoside termini indeed bind to the respective endogenous lectin. The lectin-specific antiserum enabled us to ascertain that glycohistochemical fiber typing corresponds to enzyme histochemical typing. Moreover, biochemical purification using affinity chromatography and subsequent affinity elution revealed only the immunohistochemically detectable beta-galactoside-specific lectin. Consequently, use of a panel of neoglycoproteins, when frozen sections for histochemical analysis are not available, co

Spatial and temporal changes of cytoplasmic free calcium concentration ([Ca2+]i) in single parietal cells of guinea pig were investigated with a digital imaging microscope equipped with a microspectrofluorometer, using a Ca2+-sensitive dye, fura-2. Intracellular distribution of [Ca2+]i was not homogeneous, but there were two kinds of [Ca2+]i gradient in the resting parietal cells, one a continuous gradient increasing towards the plasma membrane and a second discontinuous gradient (Ca2+ plateau) in some restricted regions of the cytoplasm. When treated with gastrin, only about 40% of parietal cells in the gastric gland responded with an almost twofold increase in the average resting [Ca2+]i of 52.4 +/- 7.1 nM. In the responding cells, the discontinuous plateaus transiently enlarged to the entire cytoplasm. In marked contrast, all of these cells responded to Ca2+ ionophore ionomycin. We also found that when provoked by gastrin Ca2+ transient in the parietal cells in the gastric gland often propagated to some adjacent cells, and occasionally spontaneous Ca2+ transient and oscillation were observed even in the resting state.

The rate of progression through the cell cycle was determined in five human glioma cell lines by a new sequential immunohistochemical staining technique. The cells were labeled first with iododeoxyuridine (IdUrd) for 1-3 hr and then with bromodeoxyuridine (BrdUrd) for 30 min. Labeled cells were identified with Br-3, a monoclonal antibody that recognizes only BrdUrd, and with IU-4, an antibody that recognizes both IdUrd and BrdUrd. Each slide was stained sequentially, first with the immunoperoxidase method for Br-3 and then with the alkaline phosphatase-anti-alkaline phosphatase method for IU-4. Cells that were positive only for IU-4 represented the fraction of S-phase cells that passed into the G2 phase during the period of incubation with IdUrd. The rates of progression measured by this method were constant in each cell line and resulted in smaller standard errors than were obtained by measurements from specimens stained singly for IdUrd and BrdUrd in different slides. The duration of the S-phase calculated from this fraction in the five cell lines ranged from 8-13 hr; the estimated potential doubling times were 25-32 hr and were very similar to the actual doubling times.

Rat monoclonal antibodies (MAb) directed to mouse Ig heavy and light chain determinants were produced. A rat anti-mouse light chain MAb (RAMOL-1) which bound to all (24/24) mouse Ig of the kappa light chain type and with varying strength to 4/4 lambda light chain-bearing Ig was evaluated as a general secondary reagent, together with two MAb that bound to the heavy chain of mouse IgG. They were conjugated with biotin or FITC and used in immunohistochemical and immunofluorescence assays to detect mouse monoclonal antibodies binding to antigens expressed in rat and human tissues and cells. As compared to commercially available polyclonal reagents, RAMOL-1 gave higher staining contrast by showing lower background staining and equal or higher staining of the primary MAb tested. This was a result of two main effects. First, crossreactivity with endogenous Ig and tissue type-specific determinants was eliminated. With polyclonal anti-mouse Ig reagents, binding to endogenous Ig was noted in vascular spaces and on Ig-bearing cells, and to rat gastric mucosa and epithelial tumor tissue in frozen tissue sections, even when diluted in high concentrations of serum homologous to the tissue. Second, binding of the secondary reagent was reduced to cells and tissues prone to have high nonspecific binding capability, such as monocytes/macrophages and formalin-fixed, paraffin-embedded tissue. Owing to unlimited and reproducible access to this homogeneous reagent, RAMOL-1 is used as second antibody to standardize the procedure used for immunohistochemical grading of human malignant tumors by determination of blood group antigen expression detected with mouse MAb.

A monoclonal antibody (3-B-3) to chondroitin 6-sulfated proteoglycan was used with immunoperoxidase electron microscopy to study the relationship of chondrocyte cytoplasmic processes and matrix vesicles in rat epiphyseal growth plate cartilage. Immunoperoxidase staining of the chondrocyte plasmalemma was found at all levels in the growth plate and was most prominent in the hypertrophic zone. The plasmalemma and matrix of the cytoplasmic process often demonstrated stronger reactivity than the remainder of the cell surface. Matrix vesicles showed weak to strong surface or internal reactivity. The majority of them stained very similarly to the cytoplasmic process. X-ray microanalysis of specimens processed by rapid freezing and freeze substitution confirmed that both sulfur and calcium were localized within or in close association with both the cytoplasmic process and the matrix vesicle, suggesting a chemical combination of calcium with sulfated proteoglycans at both sites. These results indicate that there is a selective increase in the concentration of membrane-associated sulfated proteoglycan and calcium in the cell process, from which matrix vesicles may be released into the extracellular matrix.

We describe the synthesis of four phalloidin derivatives conjugated with biotin. An aminomethyldithiolane derivative of ketophalloidin was used as a reactive starter compound, and biotin residues were coupled to this molecule either directly, separated by spacer chains comprised of one or two glycyl residues, or of a 12-atom long chain constructed from succinic acid and hexamethylendiamine. Although all products still displayed a high affinity for F-actin, as seen in competition experiments with [3H]-demethylphalloidin, only the one with the longest spacer (BHPP) showed specific and high-affinity decoration of actin filaments in permeabilized cells, in conjunction with FITC-coupled avidin and fluorescence microscopy. Combined with gold-streptavidin, BHPP decorated the actin filament system at the light and electron microscopic level faithfully and with satisfactory density. Actin filaments polymerized in vitro from purified protein were not as densely labeled as had been expected. However, in all these experiments the new phalloidin probe, when combined with avidin or streptavidin, yielded clear and highly specific labeling of F-actin. Therefore, this system is useful to identify and localize actin unambiguously in microfilaments, independent of actin antibodies, and should facilitate double-label experiments on cytoskeletal components at the ultrastructural level.

The present study demonstrates calcitonin gene-related peptide (CGRP), somatostatin (SOM), bombesin (BOM), and substance P (SP) at the electron microscopic level in lumbar dorsal root axons of normal rats. The highest percentages of labeled axons were for CGRP (14%) and then, in descending order, for SP (8.6%), SOM (6.8%), and BOM (3.1%). The labeled axons were exclusively unmyelinated for SP, SOM, and BOM, and predominantly unmyelinated for CGRP. These data are consistent with the data for labeled sensory cell bodies for these same compounds. We emphasize that these peptides were immunocytochemically visualized in the dorsal roots without experimental manipulation, such as colchicine or dorsal root ligation. Quantitative sampling of this type can be used to assay changes in response to physiological stimuli in numbers of sensory axons that contain identifiable concentrations of these peptides.

To perform immunohistochemical study of the distribution of gamma-glutamyl transpeptidase in human organs, a highly specific antibody against the human enzyme is required. We prepared monoclonal antibody against gamma-glutamyl transpeptidase from human kidney, using the hybridoma technique. The antibody was of the IgG1 type and the light chain belonged to the kappa class. The antibody reacted specifically with the 63 KD heavy subunit of the enzyme. Examination of the specificity of the antibody performed by immunohistochemical staining of human kidney sections revealed that the antigen was localized on the brush border and along the basolateral membrane of the epithelial cells of both the convoluted and the straight portions of the proximal tubule. This antibody was also reactive in several human organs other than kidney, including epididymis, prostate, seminal vesicle, pancreas, and normal liver, and in human hepatoma. These findings indicate the existence of an antigenic determinant common to human kidney and other organs. The monoclonal antibody did not crossreact with mouse, rat, guinea pig, rabbit, or pig kidney.

Nitrosation and acetylation, two histochemical blocking procedures for amino groups, were used to establish the extent to which these groups intervene in the antigen-antibody reaction in immunohistochemistry. We used the peroxidase-antiperoxidase method (PAP) to demonstrate lysozyme in Paneth cells and in lamina propria mononucleocytes of human small intestine as a model system. We studied the relationship of these groups to fixation, concentration of the primary antiserum, and length of blockade, as well as the possibility of reversing blockade as proof of specificity. Our findings support the contention that amino groups are also an important factor in antigen-antibody binding, even in fixed tissue. Fixatives influence the binding process in many ways, with acetylation producing a more successful result than nitrosation in tissue fixed in Bouin without acetic acid, whereas the reverse is true in formaldehyde-fixed tissue.

The presence and activity of alkaline phosphatase in SAOS-2 and TE-85 human osteosarcoma cells grown in culture were examined at the ultrastructural level. A monoclonal antibody raised against purified human bone osteosarcoma alkaline phosphatase was used to localize the enzyme in cultures of the osteosarcoma cells. Similar cultures were analyzed for alkaline phosphatase activity using an enzyme cytochemical method with cerium as the capture agent. Alkaline phosphatase was immunolocalized at the light microscopic level in an osteogenic sarcoma and ultrastructurally on the SAOS-2 cell membrane and the enclosing membrane of extracellular vesicular structures close to the cells. In contrast, the TE-85 cells were characterized by the absence of all but a few traces of immunolabeling at the cell surface. Enzyme cytochemical studies revealed strong alkaline phosphatase activity on the outer surface of the SAOS-2 cell membrane. Much lower enzyme activity was observed in the TE-85 cells. The results support biochemical data from previous studies and confirm that SAOS-2 cells have a significantly greater concentration of alkaline phosphatase at the plasma membrane.

Platelets have been implicated in mesangial cell proliferation in experimental and clinical glomerular disease. In this study, the temporal relationship between release of platelet secretory cationic proteins (PSCP) and progression of mesangial hyperplasia was examined in a model of mesangial proliferative glomerulonephritis induced by Habu snake venom (HSV). Intravenous injection of HSV (2 mg/kg body wt) led to capillary dilatation and ballooning into cysts filled with prominent platelet aggregates at 8 hr and 24 hr. At 48 hr, lesions were heterogeneous, some exclusively cystic, others exclusively nodular (comprised of confluent proliferative mesangial cells). Most lesions were mixed, showing features of cystic lesions containing clusters of proliferating cells. At 72 hr, all lesions were exclusively nodular. These lesions were associated with persistent localization of PSCP, as demonstrated by immunofluorescence microscopy. At 8 hr, PSCP were restricted primarily to platelets, became more intensified and diffuse at later time intervals, and by 72 hr was demonstrated in a homogeneous pattern interspaced throughout the nodular lesions. Studies utilizing antiserum to a specific platelet secretory protein, platelet factor 4 (PF4), showed an identical pattern of glomerular localization. Thus, before and during the proliferative phase of nodular formation, mesangial cells are exposed to a milieu replete with PSCP, some of which are presumably biologically active, suggesting a potential role for platelet-secreted proteins in mesangial hyperplasia in this model.

After injection of [3H]-1,25(OH)2-vitamin D3 (soltriol), nuclear labeling is found in Sertoli cells of testes, being highest at the stage of spermiosis, in epithelium of efferent ductules and caput epididymidis and in connective tissue cells of epididymis, in lamina propria and muscular sheath of deferent duct, and in epithelium and muscular sheath of dorsal and ventral prostate of the mouse. This labeling pattern is characteristic for [3H]-soltriol and differs from that for [3H]-dihydrotestosterone and [3H]-estradiol, although with overlap. The nuclear labeling with [3H]-soltriol suggests an action of the hormone on certain processes during spermatogenesis, on sperm maturation, on epididymal fluid resorption, and on secretion and transport of spermatozoa.

Antiserum to epithelial membrane antigen and three monoclonal antibodies (MAb) to milk-fat globule membranes immunocytochemically stain only epithelial cells, whereas a fourth reacts also with myoepithelial cells in inter- and intralobular ducts of human breast. Staining with peanut lectin shows a gradual increase for epithelial cells, from little or no staining in ducts through variable staining in ductules to intense staining in secretory alveoli. Antisera and MAb to vimentin, smooth-muscle actin, MAb to the common acute lymphoblastic leukemia antigen and to a glycoprotein of 135 KD stain myoepithelial cells in main ducts, but this staining is reduced in inter- and intralobular ducts and ductules. MAb to epithelial-specific keratin 18 stain a minor population of ductal epithelial cells, the major population of epithelial cells in interlobular (ILD) and extralobular terminal ducts (ETD), and epithelial cells in a minority of ductules. In lactating glands most epithelial cells in ductules are stained, but the alveolar and myoepithelial cells are unstained. Keratin MAb PKK2 and LP34 strongly stain myoepithelial cells, but only a minor population of epithelial cells in main ducts. However, these MAb stain principally the epithelial cells in ILD, ETD, and a minority of ductules. In lactating glands most epithelial cells are stained in ductules, but the myoepithelial and not the alveolar cells are stained intensely in secretory lobules. It is suggested that the unusual staining pattern of cells found principally in the ILD, ETD, and some ductules may represent regions of growth and/or subpopulation(s) of cells intermediate between epithelial and myoepithelial cells.

Recent classification of amyloidosis is based on the chemical type of amyloid protein involved. In this study, routinely embedded kidney biopsies from nine patients with generalized amyloidosis and renal involvement were tested by immunoelectron microscopy, using the protein A-gold technique, with a panel of antibodies against the following amyloid proteins: AA, A lambda, A kappa and AF. Among the antibodies, the anti-AA was monoclonal (mc1) and the others polyclonal. In all nine cases, only one type of antibody reacted with each amyloid type. Six cases were classified as AA and three cases as A lambda type. These classifications were in agreement with the clinical data and the results of serum and urine immunoelectrophoresis. The gold particles were always associated with amyloid fibrils. No reaction was evident when an amyloid type was stained by a non-corresponding antibody, or in the four control cases without amyloid. The results show that antigenic classification of amyloid is feasible on routinely processed ultra-thin epoxy sections by immunoelectron microscopy, and thus affords the possibility of retrospective studies.

We have developed a quantitative histochemical assay for measurement of succinate dehydrogenase (SDH) activity in single motoneurons. A computer image processing system was used to quantify the histochemical enzyme reaction product and to follow the time course of the reaction. The optimal concentration for each of the ingredients of the incubation medium for the SDH reaction was determined and the importance of using histochemical "blanks" in the determination of enzymatic activity was demonstrated. The enzymatic activity was linear with respect to reaction time and tissue thickness. The procedure described meets the criteria generally considered essential for establishment of a quantitative histochemical assay. The assay was then used to examine the SDH activity of cat and rat motoneurons. It was found that motoneurons with a small soma size had a wide range of SDH activity, whereas those with a large soma size were restricted to low SDH activity.

Using lectin staining methods in combination with exo- and endo-glycosidase digestion procedures, we analyzed the chemical structure of different types of blood group-related substances in serous cells of formalin-fixed, paraffin-embedded human submandibular glands. Serous cells produced only H antigen; A and B antigens were not present, and the expression of H antigen is dependent on the secretor status of the tissue donor. Although reactivity with Ulex europaeus agglutinin I (UEA-I) was not markedly reduced by alpha-L-fucosidase digestion, an affinity for peanut agglutinin (PNA) was seen after fucosidase digestion in the cells from secretors. In those from nonsecretors, no PNA reactivity appeared after enzyme digestion. On the other hand, sialidase digestion elicited PNA reactivity in serous cells irrespective of the donor's secretor status. PNA reactivity observed after fucosidase or sialidase digestion was susceptible to endo-alpha-N-acetylgalactosaminidase (endo-GalNAc-dase) digestion. SBA reactivity in UEA-I-negative cells from secretors, or in cells from fetuses and newborn infants, was markedly reduced by beta-galactosidase digestion. After galactosidase digestion, reactivity with Griffonia simplicifolia agglutinin II (GSA-II) appeared in the corresponding cells. This GSA-II reactivity was almost completely eliminated by subsequent beta-N-acetylhexosaminidase digestion. Whereas PNA reactivity in these cells was not reduced by beta-galactosidase treatment, it was significantly diminished by endo-GalNAc-dase digestion. These results suggest that at least two kinds of precursor disaccharides are produced in submandibular serous cells, i.e., SBA-reactive D-galactose-(beta 1-3,4)-N-acetyl-D-glucosamine and PNA-reactive D-galactose-(beta 1-3)-N-acetyl-D-galactosamine alpha 1-serine or threonine (O-glycosidically linked Type 3 chain or T antigen). Final fucosylation and synthesis of these two types of precursor chain appear to be under the control of the secretor gene.

12-Lipoxygenase oxygenates the 12 position of arachidonic acid and produces its 12-hydroperoxy derivative. The enzyme is found in greatest amounts in porcine leukocytes and is distributed widely in various other tissues. An anti-12-lipoxygenase antibody was raised in rabbits with the immunoaffinity-purified enzyme as an antigen and was used in immunohisto- and cytochemical studies on the enzyme, the physiological significance of which remains to be clarified. When peripheral blood cells were examined by immunoelectron microscopy, the enzyme was found in neutrophils and monocytes but was not detected in lymphocytes, platelets, and erythrocytes. In immunostained neutrophils and monocytes the enzyme was localized in the cytosol but was not clearly detected in the plasma membrane, nuclear membrane, endoplasmic reticulum, and other organelles. Several other organs known to contain considerable amounts of 12-lipoxygenase were also investigated immunohistochemically, i.e., alimentary tract (ileum and jejunum), lymphatic organs (spleen, lymph node, and thymus), ovary, lung, liver, and others. In these organs, resident mast cells and granulocytes infiltrating the interstitial tissues were positively immunostained. The enzyme was not detected in parenchymal cells of these organs under our experimental conditions.

The aim of this study was to localize the high-affinity uptake of [3H]-GABA in Langerhans islets of rats aged 2.5, 7.5, and 75 days. On high-resolution autoradiography, cells presenting characteristic somatostatin granules were labeled, whereas others containing similar granules appeared nearly devoid of silver grains. Immunogold detection with antisomatostatin antibodies and high-resolution autoradiography suggested that uptake of GABA is indeed performed by somatostatin cells. To test the heterogeneity of uptake frequency in somatostatin cells, a second approach, coupling immunohistochemistry with anti-somatostatin, anti-PP, anti-glucagon, anti-glicentin, and anti-CCK antibodies, and low-resolution autoradiography, was applied on paraffin sections. It demonstrated that the uptake ability is not characteristic of all the somatostatin cells but of only a subpopulation of them. A few cells not immunoreactive to the anti-somatostatin antiserum also appeared to be able to take up GABA. Moreover, except for a rare few, the PP-glucagon-, glicentin-, and CCK-39-immunoreactive cells were not labeled by autoradiography.

Double-label fluorescence microscopy was used to demonstrate the efflux activity of the multidrug transporter in single cultured cells. NIH3T3 cells expressing a transfected MDR1 gene (NIH3T3-MDR) were treated with vinblastine or daunomycin. The accumulation of vinblastine was monitored by examining the morphology of tubulin in cells, using immunofluorescence. Overnight treatment of drug-sensitive cells caused disassembly of microtubules and formation of paracrystals; the absence of vinblastine effects was evident by the presence of intact microtubules. Daunomycin accumulation was detected in nuclei using the inherent fluorescence of the drug with rhodamine epifluorescence microscopy. Drug efflux in multidrug-resistant cells was inhibited with verapamil. When multidrug-resistant cells were treated overnight in vinblastine, an effect of 0.5 microM vinblastine on microtubules was seen only in the presence of verapamil. Similarly, when cells were treated with daunomycin, this drug accumulated in nuclei only when verapamil was present. When cells incubated with vinblastine and verapamil were washed free of drugs, they did not accumulate daunomycin in a subsequent incubation, indicating that the multidrug transporter was still active; this occurred even though the morphologic effects of vinblastine persisted. Cells incubated with vinblastine alone showed an immediate inhibition of efflux activity when verapamil was subsequently added with daunomycin. These results show that the efflux activity of the multidrug transporter can be rapidly manipulated by agents such as verapamil, despite a prior history of drug treatment, and that the effects of inhibition of the transporter are rapidly reversible.

The immunoreactivity of anti-neuron-specific enolase (NSE) and anti-Leu-7 on formalin-fixed sections of human fetal salivary gland epithelium was determined by the avidin-biotin-peroxidase complex (ABC) method. In addition, expression of some neuropeptides such as vasoactive intestinal polypeptide (VIP), somatostatin (SRIF), and substance P in the human salivary gland epithelium during the gestational period was observed, whereas the other polypeptides examined, including glucagon, cholecystokinin (CCK), Leu-enkephalin, and calcitonin were absent. NSE and Leu-7 immunoreactivity in the fetal salivary gland epithelium was observed solitarily or in groups commonly restricted to the developing duct epithelium. Positive immunoreactivity was observed in 46 cases with NSE (73%) and 44 cases with Leu-7 (70%) in 63 fetal salivary glands examined. In contrast, the incidence of positive cases stained with neuropeptides was lower than those of NSE and Leu-7 immunoreactivity in the human fetal salivary gland epithelium. These findings indicate that certain neuropolypeptides, as well as VIP, SRIF, and substance P present in the human fetal salivary gland epithelium may play a significant role in the development of the gland.

Intratumor heterogeneity is a major problem in immunodiagnosis and treatment of carcinomas. To elucidate the well-known heterogeneity in transitional-cell carcinomas of the ability to express blood group ABO isoantigens, a stereological estimate of the mean nuclear volume in areas expressing blood group antigens was compared to the estimate from areas of identical pathological grade at which antigen expression was deleted. Four microscopic fields were examined from antigen-positive and four from antigen-negative areas in sections from 21 blood group O and 20 blood group A individuals. The sections were stained before examination by an indirect peroxidase method using monoclonal anti-H and anti-A antibodies. The mean nuclear volume increased, as expected, with increasing pathological grade. In blood group O individuals the mean nuclear volume was 241.5 microns 3 in antigen-positive areas and 338.2 microns 3 in antigen-negative areas (2p less than 0.0005) of identical pathological grade. In group A individuals the mean nuclear volume was 217.1 microns 3 in positive areas and 351.1 microns 3 in corresponding negative areas (2p less than 0.0025). The variation in volume parameter was essentially caused by a true variation between tumors (greater than 82%). The results indicate a complex biological mechanism associated with the cellular ability to express blood group antigens.

This report describes problems commonly encountered in cryosectioning of fragile tissues, such as jamming and scrambling of sections between knife and anti-roll plate. The electrostatic nature of the factors causing these derangements is demonstrated here using simple methods, and several modifications to the anti-roll plate surface are tested for their help in obviating these difficulties. The anti-roll plate material found to be most effective consists of a metal oxide-coated glass which is commercially available at low cost.

Ultra-thin sections of various tissues were stained with ethidium bromide or propidium iodide, two fluorescent markers widely used for quantitation of nucleic acids. The fluorochromes, tested at different concentrations, were then revealed by incubation of the sections with neutralized phosphotungstic acid. We showed that at the electron microscopic level only nucleic acid-containing structures are revealed. Chromatin, nucleolus, and ribosomes appear to be stained by the end-product of the reaction. Furthermore, controls with proteases and nucleases showed that the staining is related to the binding of the fluorochromes to DNA and RNA and to the subsequent detection of the dyes by neutralized PTA.