Meshwork Pattern Research Articles

CDKN2A and MC1R variants influence dermoscopic and confocal features of benign melanocytic lesions in multiple melanoma patients

Non-invasive diagnostic tools are effective in the histomorphological study of melanocytic lesions. The role of melanoma susceptibility genes on melanocytic nevi histopathological features is not clear. The current study aimed to correlate genetic alterations and histomorphological features of melanocytic nevi. Clinical, dermoscopic and confocal features of 34 multiple melanoma patients and 34 controls were compared. Among patients with melanoma, carriers of CDKN2A mutations and/or MC1R variants, and wild-type genes were also compared. In patients with melanoma, a lighter phototype (P=0.051), a higher number of nevi (P<0.01) and clinically atypical nevi (P<0.01) were observed. At dermoscopy, these nevi showed a complex pattern (P=0.011), atypical network (P=0.018) and irregular pigmentation (P=0.037); at confocal, an irregular meshwork pattern (P=0.026) with atypical nests (P=0.016) and an inflammatory infiltrate (P=0.048) were observed. Among patients with melanoma genetically tested, CDKN2A G101W mutation carriers were more frequently younger (P=0.023), with clinically atypical nevi (P=0.050), with cytological atypia (P=0.033) at confocal. G101W mutation and MC1R variants carriers showed hypopigmented nevi (P=0.002) and, at confocal, roundish cells infiltrating the junction (P=0.019). These data suggest an influence of CDKN2A mutation and MC1R variants in the development of dysplastic melanocytic lesions. Non-invasive histomorphological evaluation, together with genetic studies, improves melanoma risk identification and early diagnosis, for a patient-tailored management.

Towards an in vivo morphologic classification of melanocytic nevi

Nevi are common benign neoplasms and the main diagnostic entity in the differential diagnosis of melanoma. Reflectance confocal microscopy (RCM), a novel technique for skin imaging at cellular-level magnification, has been shown to be useful for differentiating nevi from melanoma. However, systematic studies of the specific RCM features of nevi are still lacking. To describe the characteristic RCM features of common melanocytic nevi and to correlate them with histopathology. A total of 180 biopsy-proven nevi were imaged with RCM prior to excision. RCM images were evaluated for the overall nevus pattern and presence of specific RCM criteria. Upon histopathology, nevi were analysed for thickness using adapted Breslow depth and Clark's level grading. Observed RCM patterns varied according to anatomic depth of nevi. Junctional nevi were mainly characterized on RCM by a Ringed pattern, indicating a predominantly single cell proliferation of melanocytes; in contrast, the junctional component of compound nevi appeared on RCM as a Meshwork pattern, indicating a predominantly nested-proliferation. In compound nevi, the size of dermal nests was related to the thickness of nevi. Moreover, nevi extending deeper into the dermis were more likely to display a junctional component that extended laterally beyond the dermal component and appeared on RCM as either Ringed or Meshwork pattern. Intradermal nevi showed on RCM, in almost all cases, large clods. The possibility for in vivo histopathological classification of nevi may help in attaining a better understanding of the origin of nevi and of nevus-related melanoma risk.

New Software Application for Clarifying Tear Film Lipid Layer Patterns

The lipid layer of the tear film limits evaporation during the interblink interval and also affects tear stability. This study was designed to validate a new software application designed to characterize the tear film lipid layer through texture and color pattern recognition. Using the Tearscope-plus (slit-lamp magnification ×200), the lipid layer was examined in 105 healthy young adults, and interference photographs were acquired with a Topcon DV-3 digital camera. The photographs were classified by a clinician experienced in examining lipid layer patterns (LLPs), and these classifications were used as the reference standard (reference examiner). Next, LLPs were graded using the new software and further by 2 observers (observer 1 and observer 2) with experience in examining the ocular surface. Strong correlation was detected between the categories determined by the new application and reference examiner (Cramer V 0.85-0.93, P < 0.001). The classifications made using the new application and by observer 1 and observer 2 were also consistent although correlation was weaker (Cramer V 0.56-0.87, P < 0.001). For thinner LLPs, greatest correspondence with the reference was observed using the new software (96.6%), whereas the 2 observers showed better agreement when grading thicker patterns. Notwithstanding, agreement between the 2 observers and the reference examiner was good with at least 81% matched classifications. Best agreement (96.2%) was noted between the new method and observers 1 and 2 for recognizing meshwork patterns, whereas observers 1 and 2 showed greatest correspondence when classifying color fringe patterns. The new application can objectively categorize LLPs using the Tearscope-plus.

Follicular dendritic cells: origin, function, and different disease-associated patterns

Follicular dendritic cells (FDCs) are a specialized type of antigen-presenting dendritic cells that are largely restricted to lymphoid follicles. They form dense three-dimensional meshwork patterns within benign follicles, which maintain the follicular architecture. The FDC function is to bind and retain antigens by linking to complement and immune complexes and then present these antigens to germinal center B cells that start the secondary immune response. FDCs aid in the rescue of bound B cells from apoptosis, and induce the differentiation of B cells into long-term memory B cell clones or plasma cells. We will discuss the different patterns of the FDC meshwork observed in different types of reactive and neoplastic disorders, which may be due to underlying different roles that FDCs may play in these disorders and whether changes in the architecture of the FDC meshwork can be useful in routine diagnostic practice or have a prognostic value.

Digital Chromoendoscopy for Diagnosis of Diminutive Colorectal Lesions

Introduction. To compare the accuracy of digital and real-time chromoendoscopy for the differential diagnosis of diminutive (<5 mm) neoplastic and nonneoplastic colorectal lesions. Materials and Methods. This is a prospective randomized study comparing the Fujinon intelligent color enhancement (FICE) system (65 patients/95 lesions) and indigo carmine (69 patients/120 lesions) in the analysis of capillary meshwork and pit pattern, respectively. All lesions were less than 5 mm in diameter, and magnification was used in both groups. Histopathology was the gold standard examination. Results. Of 215 colorectal lesions, 153 (71.2%) were adenomas, and 62 were hyperplastic polyps (28.8%). Morphological analysis revealed 132 (61.4%) superficial lesions, with 7 (3.3%) depressed lesions, and 83 (38.6%) protruding lesions. Vascular meshwork analysis using FICE and magnification resulted in 91.7% sensitivity, 95.7% specificity, and 92.6% accuracy in differentiating neoplastic from nonneoplastic lesions. Pit pattern analysis with indigo carmine and magnification showed 96.5% sensitivity, 88.2% specificity, and 94.2% accuracy for the same purpose. Conclusion. Both magnifying virtual chromoendoscopy and indigo carmine chromoendoscopy showed high accuracy in the histopathological diagnosis of colorectal lesions less than 5 mm in diameter.

Mutations to the Formin Homology 2 Domain of INF2 Protein Have Unexpected Effects on Actin Polymerization and Severing

INF2 (inverted formin 2) is a formin protein with unusual biochemical characteristics. As with other formins, the formin homology 2 (FH2) domain of INF2 accelerates actin filament assembly and remains at the barbed end, modulating elongation. The unique feature of INF2 is its ability to sever filaments and enhance depolymerization, which requires the C-terminal region. Physiologically, INF2 acts in the secretory pathway and is mutated in two human diseases, focal and segmental glomerulosclerosis and Charcot-Marie-Tooth disease. In this study, we investigate the effects of mutating two FH2 residues found to be key in other formins: Ile-643 and Lys-792. Surprisingly, neither mutation abolishes barbed end binding, as judged by pyrene-actin and total internal reflection (TIRF) microscopy elongation assays. The I643A mutation causes tight capping of a subset of filaments, whereas K792A causes slow elongation of all filaments. The I643A mutation has a minor inhibitory effect on polymerization activity but causes almost complete abolition of severing and depolymerization activity. The K792A mutation has relatively small effects on polymerization, severing, and depolymerization. In cells, the K792A mutant causes actin accumulation around the endoplasmic reticulum to a similar extent as wild type, whereas the I643A mutant causes no measurable polymerization. The inability of I643A to induce actin polymerization in cells is explained by its inability to promote robust actin polymerization in the presence of capping protein. These results highlight an important point: it is dangerous to assume that mutation of conserved FH2 residues will have equivalent effects in all formins. The work also suggests that both mutations have effects on the mechanism of processive elongation.

Splice variant–specific cellular function of the formin INF2 in maintenance of Golgi architecture

INF2 is a unique formin that can both polymerize and depolymerize actin filaments. Mutations in INF2 cause the kidney disease focal and segmental glomerulosclerosis. INF2 can be expressed as two C-terminal splice variants: CAAX and non-CAAX. The CAAX isoform contains a C-terminal prenyl group and is tightly bound to endoplasmic reticulum (ER). The localization pattern and cellular function of the non-CAAX isoform have not been studied. Here we find that the two isoforms are expressed in a cell type-dependent manner, with CAAX predominant in 3T3 fibroblasts and non-CAAX predominant in U2OS, HeLa, and Jurkat cells. Although INF2-CAAX is ER localized in an actin-independent manner, INF2-non-CAAX localizes in an actin-dependent meshwork pattern distinct from ER. INF2-non-CAAX is loosely attached to this meshwork, being extracted by brief digitonin treatment. Suppression of INF2-non-CAAX causes fragmentation of the Golgi apparatus. This effect is counteracted by treatment with the actin monomer-sequestering drug latrunculin B. We also find discrete patches of actin filaments in the peri-Golgi region, and these patches are reduced upon INF2 suppression. Our results suggest that the non-CAAX isoform of INF2 serves a distinct cellular function from that of the CAAX isoform.

In vivo confocal microscopy for detection and grading of dysplastic nevi: A pilot study

Dysplastic nevi are thought to be precursors of melanoma during a stepwise process. However, this concept is still controversial and precise correlation between clinical and histopathologic features is lacking. In vivo confocal microscopy represents a noninvasive imaging technique producing horizontal sections at nearly histopathologic resolution. We sought to determine whether specific histologic features in dysplastic nevi have reliable correlates on confocal microscopy and to develop an in vivo microscopic grading system. Sixty melanocytic lesions with equivocal dermatoscopic aspects, corresponding to 19 nondysplastic nevi, 27 dysplastic nevi, and 14 melanomas, were analyzed by confocal microscopy and histopathology, using the Duke grading criteria. All architectural and cytologic features of the Duke grading score had significant reflectance confocal microscopy correlates. Confocally, dysplastic nevi were characterized by a ringed pattern, in association with a meshwork pattern in a large proportion of cases, along with atypical junctional cells in the center of the lesion, and irregular junctional nests with short interconnections. A simplified algorithm was developed to distinguish dysplastic nevi from melanoma and nondysplastic nevi. The contemporary presence of cytologic atypia and of atypical junctional nests (irregular, with short interconnections, and/or with nonhomogeneous cellularity) was suggestive of histologic dysplasia, whereas a widespread pagetoid infiltration, widespread cytologic atypia at the junction, and nonedged papillae suggested melanoma diagnosis. A small number of cases were evaluated because of the necessity to analyze numerous histopathologic and confocal features. The possibility to detect dysplastic nevi in vivo may lead to an appropriate management decision.

Gastric mucosal nerve density

Autonomic neuropathy is a frequent diagnosis for the gastrointestinal symptoms or postural hypotension experienced by patients with longstanding diabetes. However, neuropathologic evidence to substantiate the diagnosis is limited. We hypothesized that quantification of nerves in gastric mucosa would confirm the presence of autonomic neuropathy. Mucosal biopsies from the stomach antrum and fundus were obtained during endoscopy from 15 healthy controls and 13 type 1 diabetic candidates for pancreas transplantation who had secondary diabetic complications affecting the eyes, kidneys, and nerves, including a diagnosis of gastroparesis. Neurologic status was evaluated by neurologic examination, nerve conduction studies, and skin biopsy. Biopsies were processed to quantify gastric mucosal nerves and epidermal nerves. Gastric mucosal nerves from diabetic subjects had reduced density and abnormal morphology compared to control subjects (p < 0.05). The horizontal and vertical meshwork pattern of nerve fibers that normally extends from the base of gastric glands to the basal lamina underlying the epithelial surface was deficient in diabetic subjects. Eleven of the 13 diabetic patients had residual food in the stomach after overnight fasting. Neurologic abnormalities on clinical examination were found in 12 of 13 diabetic subjects and nerve conduction studies were abnormal in all patients. The epidermal nerve fiber density was deficient in skin biopsies from diabetic subjects. In this observational study, gastric mucosal nerves were abnormal in patients with type 1 diabetes with secondary complications and clinical evidence of gastroparesis. Gastric mucosal biopsy is a safe, practical method for histologic diagnosis of gastric autonomic neuropathy.

New insights into nevogenesis: In vivo characterization and follow-up of melanocytic nevi by reflectance confocal microscopy

Development of melanocytic nevi is a complex process. The aim of the study was to characterize the in vivo confocal microscopy patterns and histopathologic correlates of melanocytic nevi. In addition, for the first time, confocal follow-up of characteristic nevi was performed documenting histologic changes in nevi. For the correlation study, 33 melanocytic nevi showing characteristic dermatoscopic patterns were studied by confocal microscopy. For the follow-up study 20 nevi were monitored for 12 to 18 months. Reticular nevi showed two different confocal patterns, ringed and meshwork, mostly corresponding to lentiginous and nested junctional patterns, respectively. Globular nevi presented large junctional clusters, whereas cobblestone nevi were constituted by dermal dense melanocytic clusters. Homogeneous nevi did not show distinctive confocal and histopathologic findings. Nevi with a rim of globules presented a meshwork pattern with junctional clusters at the periphery. At the confocal follow-up study all lesions showed limited dynamic changes resulting in stable dermatoscopic and confocal patterns, but 3 globular nevi with junctional nests at baseline evolved into reticular-meshwork pattern nevi with peripheral rim of globules-junctional nests. Longer confocal follow-up of more melanocytic nevi is required to confirm this theory and to validate our preliminary findings. A model explaining the nevus classification and patterns of evolution of nevi observed in the study was proposed.

The Role of the Mitochondrial Glycine Cleavage Complex in the Metabolism and Virulence of the Protozoan Parasite Leishmania major

For the human pathogen Leishmania major, a key metabolic function is the synthesis of thymidylate, which requires 5,10-methylenetetrahydrofolate (5,10-CH(2)-THF). 5,10-CH(2)-THF can be synthesized from glycine by the mitochondrial glycine cleavage complex (GCC). Bioinformatic analysis revealed the four subunits of the GCC in the L. major genome, and the role of the GCC in parasite metabolism and virulence was assessed through studies of the P subunit (glycine decarboxylase (GCVP)). First, a tagged GCVP protein was expressed and localized to the parasite mitochondrion. Second, a gcvP(-) mutant was generated and shown to lack significant GCC activity using an indirect in vivo assay after incorporation of label from [2-(14)C]glycine into DNA. The gcvP(-) mutant grew poorly in the presence of excess glycine or minimal serine; these studies also established that L. major promastigotes require serine for optimal growth. Although gcvP(-) promastigotes and amastigotes showed normal virulence in macrophage infections in vitro, both forms of the parasite showed substantially delayed replication and lesion pathology in infections of both genetically susceptible or resistant mice. These data suggest that, as the physiology of the infection site changes during the course of infection, so do the metabolic constraints on parasite replication. This conclusion has great significance to the interpretation of metabolic requirements for virulence. Last, these studies call attention in trypanosomatid protozoa to the key metabolic intermediate 5,10-CH(2)-THF, situated at the junction of serine, glycine, and thymidylate metabolism. Notably, genome-based predictions suggest the related parasite Trypanosoma brucei is totally dependent on the GCC for 5,10-CH(2)-THF synthesis.

Type IV Collagen Immunostaining Is a Simple, Reliable Diagnostic Tool for Distinguishing Between Adenomatous and Normal Pituitary Glands

Pituitary adenomas are clinically diagnosed based on radiologic studies and/or secondary effects of hormone production. Definitive pathologic identification relies on immunohistochemical detection of a clonal population of hormone-producing cells. However, not all adenomas secrete hormones, so performing a battery of stains is inefficient. Reports have shown decreased type IV collagen in the stroma of other epithelial tumors. To validate type IV collagen immunohistochemistry as a diagnostic method. We immunostained 27 adenomas and 19 normal pituitaries. The areas with the sparsest type IV collagen fibers were viewed at 3 magnifications (x10, x20, and x40 objectives), counting 1, 3, or 10 microscopic fields. A field was scored as "traversable" if a path existed from any point on the periphery of the field to a point on the approximately opposite periphery that did not cross any stained fibers. Results were compared with reticulin staining and to the existing diagnosis previously determined by histology, hormone immunostaining, and clinical correlation. Adenomas have less type IV collagen in their basement membranes, leading to sparser, trabecular staining in neoplasms versus a more rigid meshwork pattern in normal glands. One might envision the stained fibers as maze walls--one can traverse medium-powered fields in an adenoma, but one hits dead ends and gets trapped in those of a normal gland. Finding a single representative x10 field to be traversable was 97.5% sensitive and 96.5% specific for an adenoma. Reticulin staining yielded identical results. Type IV collagen immunostaining is a simple and reliable method of diagnosing pituitary adenomas.

Meshwork pattern is an important risk factor for development of hepatocellular carcinoma in patients with HBV-related chronic hepatitis and cirrhosis

We analyzed the importance of ‘meshwork pattern’, a sign representing severe irregularity on the intra-hepatic echogram, in hepatitis B virus (HBV)-related chronic hepatitis and cirrhosis, as a risk factor for development of hepatocellular carcinoma (HCC). Two hundred and thirty-one patients (143 men and 88 women) with HBV-related chronic hepatitis and cirrhosis who visited our hospital from January 1993 to December 1994 were enrolled in this study. Since enrollment, abdominal ultrasonography had in principle been performed every 3 months for cirrhotic patients and every 4–6 months for patients with chronic hepatitis for HCC screening. Cumulative HCC incidences in patient groups positive or negative for meshwork pattern were calculated by the Kaplan–Meier method. The incidence of HCC was significantly higher in the group positive for meshwork pattern (average incidence per year: 4.4%) than in the group negative for it (average incidence per year: 0.5%) ( P<0.0001, Mantel–Cox test). On regression analysis with Cox's proportional hazards model, sex, α-fetoprotein and meshwork pattern were selected as independent risk factors for HCC. In conclusion, meshwork pattern appears to be an ultrasonographic sign useful for detecting a latent risk factor for HCC in patients with HBV-related chronic hepatitis and cirrhosis.

Chromatin structure and nuclear remodeling.

Nuclear architecture is remodeled during interphase in response to changes in gene activity as well as to changing structural and functional requirements during cell division. Using the monoclonal antibody mAb2A, we have identified two proteins that appear to play important roles in these processes: JIL-1 is a tandem serine-threonine kinase implicated in the regulation of chromatin structure, whereas Skeletor is a novel protein participating in structural nuclear remodeling during the cell cycle. Antibody staining and live imaging of JIL-1-GFP transgenic flies show that JIL-1 localizes to the gene-rich interband regions of larval polytene chromosomes and is upregulated almost twofold on the hypertranscribed male X chromosome compared with autosomes. We propose that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure. The other mAb2A antigen, Skeletor, is distributed in a nuclear meshwork pattern that can be observed in stereo pair images to reorganize during the cell cycle to form a spindle-like structure at prometaphase that is distinct from the microtubule spindle apparatus. Taking advantage of the powerful molecular and genetic approaches offered in Drosophila, the study of these two proteins promises to yield new insight into what defines nuclear architecture at the molecular level and how its remodeling is regulated.

Distribution of F-actin, α-actinin, tropomyosin, tubulin and organelles in Euglena gracilis by immunofluorescence microscopy

Euglena gracilis, a unicellular flagellated alga, can display numerous shape changes. These changes are most probably caused by a pellicle and an internal cytoskeleton. In this paper we studied the distribution of the cytoskeletal proteins actin, α-actinin, tropomyosin and tubulin in dark-adapted Euglena, using immunofluorescence microscopy. We found that F-actin, α-actinin, tropomyosin and tubulin have a distribution that is coincident in the plasma membrane and, in addition, α-actinin and tropomyosin are seen in small patches in the cytoplasm, and tubulin in the flagella. We have also studied the distribution of the endoplasmic reticulum, nucleus, and Golgi apparatus of these cells, using fluorescent probes. Both the endoplasmic reticulum and the Golgi apparatus have a meshwork pattern distributed throughout the cytoplasm, and the nucleus has a chromatin evenly distributed in the nucleoplasm.

Differential Expressions of Laminin and Matrix Metalloproteinases in the Metastatic and Non-metastatic Cells Isolated from Squamous Cell Carcinoma(O-1N).

Expressions of laminin and matrix metalloproteinases (MMPs) were investigated in metastatic and non-metastatic cells isolated from an experimental model of lymph node metastasis (O-1N). By Northern blot analysis, the metastatic cells expressed mRNA for laminin 6 days after plating, whereas the expression was very weak in the non-metastatic cells at the same stage. Immunohistochemical signals for laminin observed initially in the cytoplasm gradually increased in intensity and number with time and showed a honeycomb-like meshwork pattern at 7 days in both cells. The 92kD gelatinolytic activity (MMP-9) on zymography was stronger in the metastatic cells than in the non-metastatic cells. The 72kD band (MMP-2) was detected equally in both cells. The 59kD and 56kD caseinolytic activities (MMP-3) were observed only in the metastatic cells. The results indicate that the enhanced gene transcription and biosynthesis of laminin and concordant active destruction of basement membrane by MMPs in the metastatic cells may be involved in the process of lymph node metastasis in O-1N.

Trigeminal sensory innervation on perforators of the circle of willis in rabbits by wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing

Distribution patterns of sensory innervation from the trigeminal ganglion to the perforators of the circle of Willis in rabbits were investigated by wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) anterograde tracing. Twenty Japanese white rabbits were anesthetized by inhaling 1% halothane. Using a microsurgical technique, 4 μl of 2% WGA-HRP in 1 M KCl solution, colored with brilliant blue, was micro-injected into the medial part of the left trigeminal ganglion in 14 animals with a pressure injection system. Another six served as controls to exclude the possibility of labeling non-trigeminal axons. Forty-eight hours later, the perforators in the cisternal and intracerebral segments along with their parent arteries were dissected from the brain according to Dacey's dissecting technique after transcardial perfusion, reacted with the 3,3′,5,5′-tetramethyl benzidine method of Mesulam. The results revealed that sensory nerves on the perforators of the circle of Willis were less densely innervated than those on their parent arteries due to the difference in diameter. The posteromedial perforating arteries arising from the Pl segment of the posterior cerebral artery to the tegmentum, posteroventral thalamus and posterior hypothalamus were more prominently and consistently innervated than other perforators. The sensory fibers were seen on the cisternal segment of the perforating arteries. A parallel or twisted pattern was found in the perforators less than 100 μm in diameter, while a meshwork pattern was visualized in the proximal part of some bigger ones. Fine sensory fibers could be traced on the perforators as small as 40 μm in diameter. The present study demonstrates for the first time the detailed distribution patterns of sensory nerves from the trigeminal ganglion to perforators of the circle of Willis in rabbits. Pathophysiological implications of the findings are discussed in relation to cerebral vasospasm following subarachnoid hemorrhage.

Immunohistologic Detection of the Primary Follicle (PF) human fetal and newborn lymph node anlages

The primary follicle (PF) emerges as a globular nest of follicular dendritic cells (FDC) and lymphocytes in the lymph node anlage in the 16th gestational week. It increases in size with age but no germinal center is found until several months later, after birth. Using a panel of monoclonal antibodies, the authors have defined phenotypes of component cells of the PF. The PF contains a B-cell population including IgM+, CD20+, CD21+, and CD24+ cells, together with a T-cell population including CD3+, CD4+, CD5+, and CD8+ but no IgG+ cells. It also contains many CD5+ B cells and several IgD+ and alkaline phosphatase-positive cells but few CD15+, CD25+, CD30+, CD38+, and Ki-67+ cells. CD24+ and dendritic reticulum (DRC)-1+ cells show an irregular meshwork pattern in the PF. CD5+ B cells appear even before the formation of the PF and increase after formation of the PF. The lymphocytic phenotype of the PF is similar to that of the mantle zone of the secondary follicle. The phenotypic characteristics indicate that the PF appears as an aggregation of CD5+ B cells and plays an important role as the ancestor of the secondary follicle as well as helper T cells and FDC.

Distribution patterns of sensory innervation from the trigeminal ganglion to cerebral arteries in rabbits studied by wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing.

Distribution patterns of sensory nerves from the trigeminal ganglion to cerebral arteries in rabbits were studied by the wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing technique along with the 3,3',5,5'-teramethylbenzidine method. Labeled sensory nerves were densely distributed in whole-mount specimens of cerebral arteries after the injection of wheat germ agglutinin-conjugated horseradish peroxidase into the trigeminal ganglion. The characteristics of the innervation in rabbits included: 1) cerebrovascular sensory nerves were more dense in the ipsilateral side than in the contralateral side; 2) the anterior cerebral artery was less densely innervated than the posterior cerebral artery; 3) labeled nerves on the proximal segment of arteries were more prominent than those on the distal segment. The smallest pial branches of the middle cerebral, posterior cerebral, and anterior inferior cerebellar arteries overlying the fine sensory nerves were 50, 75, and 80 microns in diameter, respectively. Two patterns of the sensory innervation were seen. A meshwork pattern was mainly observed in the circle of Willis and the proximal segments of its main branches, as well as in the upper two thirds of the basilar artery; a parallel or slightly twisted pattern was shown in the small pial arterioles. Our results in this study may be useful to understand better the trigeminocerebrovascular system.

Intercellular adhesion molecule-1 (ICAM-1) staining of reactive and neoplastic follicles. ICAM-1 expression of neoplastic follicle differs from that of reactive germinal center and is independent of follicular dendritic cells

Intercellular adhesion molecule-1 (ICAM-1) is expressed on follicular dendritic cells (FDC), and the ICAM-1/LFA-1 pathway is essential for affinity selection of activated B-cells in germinal centers (GC). The expression of ICAM-1 has been studied by immunostaining methods in GC, but not in neoplastic follicles (NF). The authors studied the expression of ICAM-1 by the avidin-biotin-peroxidase complex (ABC) method with frozen sections in GC of reactive nodes (n = 22) and NF of follicular lymphomas (n = 19), in comparison with FDC staining. GC stained uniformly for ICAM-1, with staining intensity varying little from node to node, and follicular borders were well demarcated from the surroundings. Endothelial cells within GC did not stain whereas those outside stained strongly. In contrast, NF stained variably from tumor to tumor, and in any given tumor. Characteristically, follicular borders were not demarcated, and stained areas were difficult to define due to the lack of demarcation, with the exception of large cell type with diffuse areas (n = 2). Endothelium of intrafollicular vessels stained prominently (12 of 19), and appeared to contribute to the staining intensity of the follicles. FDC staining revealed a meshwork pattern in GC which was similar to that of ICAM-1. The FDC mesh-work pattern was present in 15 tumors. The pattern was remarkably uniform with sharply defined borders, which contrasted starkly to the variable staining and lack of follicular borders in the ICAM-1 stain of the same tumors. The staining pattern of follicles for ICAM-1 was similar to that for FDC in reactive nodes, but distinct from the latter in follicular lymphomas. An appropriate expression of ICAM-1 appears to be essential for normal GC, as the alteration of the expression coincides with the malignant transformation of GC. The altered expression of ICAM-1 may be useful in distinguishing NF from reactive GC.