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PubMed1990

The venous territories (venosomes) of the human body: experimental study and clinical implications.

The venous architecture of the integument and the underlying deep tissues was studied in six total-body human fresh cadavers and a series of isolated regional studies of the limbs and torso. A radiopaque lead oxide mixture was injected, and the integument and deep tissues were dissected and radiographed. The sites of the venous perforators were plotted and traced to their underlying parent veins that accompany the source (segmental) arteries. A series of cross-sectional studies were made in one subject to illustrate the course of the perforators between the integument and the deep tissues. The veins were dissected under magnification to identify the site and orientation of the valves. Results revealed a large number of valveless (oscillating) veins within the integument and deep tissues that link adjacent valved venous territories and allow equilibration of flow and pressure throughout the tissue. Where choke arteries define the arterial territories, they are matched by boundaries of oscillating veins in the venous studies. The venous architecture is a continuous network of arcades that follow the connective-tissue framework of the body. The veins converge from mobile to fixed areas, and they "hitchhike" with nerves. The venous drainage mirrors the arterial supply in the deep tissues and in most areas of the integument in the head, neck, and torso. In the limbs, the stellate pattern of the venous perforators is modified by longitudinal channels in the subdermal network. However, when an island flap is raised, these longitudinal channels are disconnected, and once again the arterial and venous patterns match. Our venous studies add strength to the angiosome concept. Where source arteries supply a composite block of tissue, we have demonstrated radiologically and by microdissection that the branches of these arteries are accompanied by veins that drain in the opposite direction and return to the same locus. Hence each angiosome consists of matching arteriosomes and venosomes. The clinical implications of these results are discussed with particular reference to the design of flaps, the delay phenomenon, venous free flaps, the pathogenesis of flap necrosis, the "muscle pump," varicose veins, and venous ulceration.

Aged↗
PubMed2005

Protecting RNA in fixed tissue: an alternative method for LCM users.

RNA degradation is a major drawback in most common fixation protocols in techniques that require both RNA integrity and preserved morphology, such as laser capture microdissection (LCM) followed by RT-PCR. Moreover, RNA isolation kits especially developed for LCM samples are very expensive. Our aim was to determine an easy protocol that ideally must provide an acceptable morphology, allow proper laser capture of selected cells and improve RNA yield and quality. In this study, retinas were dissected, briefly incubated in a RNA preservative and fixed in 2% paraformaldehyde before being cut on a cryostat. LCM was carried out in retinal sections for immediate RNA isolation, by using TRIzol common protocol with minor modifications. Real-time PCR was performed next in order to compare availability of RNA from samples submitted to different protocols. The use of the RNA preservative followed by a fast fixation did not jeopardize tissue morphology, allowing microdissection of selected cells, combined to minor modifications in usual RNA isolation procedures, significantly improved RNA yield and quality. Furthermore, only LCM samples submitted to our protocol provided amplifiable mRNA, as determined by real-time PCR. Taken together, the combination of the described procedures resulted in a reliable alternative for LCM users.

Animals↗
PubMed2003

Heparanase-1 gene expression in normal, hyperplastic and neoplastic prostatic tissue.

Heparanase-1 (Hpa-1) has been implicated in tumour invasion and metastasis. In the present study, we evaluated the clinicopathological significance of Hpa-1 mRNA expression in prostate cancer and non-cancerous prostatic tissue by one-step polymerase chain reaction (PCR) of laser microdissected prostatic gland cells. In addition, cell type-specific expression of Hpa-1 mRNA in prostatic tissue was analysed by in situ hybridisation. Hpa-1 mRNA expression was found in 50% of normal and 40% of hyperplastic prostatic tissue. In situ hybridisation showed that Hpa-1 mRNA was strongly expressed in prostate gland cells. Of the 26 prostate carcinomas tested, 42% were positive for Hpa-1 mRNA. However, in non-cancerous prostatic tissue, Hpa-1 mRNA was significantly more often expressed than in less differentiated or more invasive prostate cancers (P<0.05). In situ hybridisation revealed only focal Hpa-1 mRNA expression in the neoplastic gland cells. Hpa-1 mRNA expression in the tumours significantly correlated with tumour differentiation and tumour stage (P<0.05). Our data indicate that Hpa-1 gene expression may be lost during dedifferentiation of prostatic gland cells.

Adult↗
PubMed1984

The biomaterial-tissue interface: a morphological study utilizing conventional and alternative ultrastructural modalities.

The interface between oral tissues and ceramic endosteal dental implants was investigated in 36 experimental cases in dog jaws. Conventional electron microscopic modalities showed those tissues adjacent to the implants to be viable with no adverse cellular response to the biomaterial. A procedure to retrieve additional ultrastructural data from previously processed biological material was developed to expand upon these data. This included surface-etching with oxygen plasma of routinely processed electron microscopy specimens and formalin fixed histological specimens for scanning electron microscopy (SEM) study; and, cryofracturing of similar histological specimens for additional transmission electron microscopic (TEM) analysis. Results from these alternative protocols supported our observations from conventional studies of the direct association of bone and epithelia to the implant. In addition, they demonstrated a unique portrayal of the epithelial maturation patterns. Further, this alternative TEM method showed excellent retention of cellular integrity and demonstrated a hemidesmosomal-external basal lamina attachment apparatus at the junctional epithelial-implant interface. This latter composite attachment structure was not retained in our previous conventional microdissection procedures. Thus, the interface between oral tissues and the single crystal sapphire endosteal dental implant could be elucidated by these protocols.

Animals↗
PubMed2004

High-quality RNA preparation for transcript profiling of osteocytes from native human bone microdissections.

Osteocytes, the most abundant bone cell type with important roles in tissue maintenance and pathological aberrations such as observed in bone metastases, are enclosed within a highly compact, calcified extracellular matrix. This location complicates analysis in native bone, with the consequence that despite their importance their in vivo molecular physiology is only poorly understood. We have examined the possibility of isolating osteocyte RNA for transcript profiling from native, frozen bone instead of employing the formalin-fixed, paraffin-embedded, decalcified version routinely used in histology, providing chemically modified and highly disintegrated RNAs. Bone tissue was tape-assisted cryosectioned and fixed to glass slides by support of UV-flash-triggered adhesive polymerization followed by quick hematoxylin-eosin staining to generate a guidance image for microdissection. Using an UVa-nitrogen laser, matrix-enclosed osteocytes were either excised and catapulted into RNA preparation vials or freed of accompanying nonosteocyte cellular material. The influences of bone sectioning, staining, and osteocyte capturing procedures on the prepared osteocyte RNAs were analyzed and the method was optimized accordingly. The obtained osteocyte RNAs showed the expected expression pattern of marker genes (reverse transcriptase-polymerase chain reaction), and, following conversion into fluorescent-labeled cDNAs, led to transcript profiles (cDNAchips; 2600 genes) with scatter-graph geometries indicating suitability for high-confidence evaluation. With the approach described here we introduce a methodological way for the characterization of the in vivo molecular physiology of osteocytes by functional genomics.

Bone and Bones↗
PubMed2006

Validation of a novel ultra-short immunolabeling method for high-quality mRNA preservation in laser microdissection and real-time reverse transcriptase-polymerase chain reaction.

Laser microdissection allows isolation of tiny samples from tissue sections for analysis of gene expression by real-time quantitative polymerase chain reaction (PCR). Although immunohistochemical labeling is often required to identify target structures, it drastically degrades mRNA so that shortened protocols are needed. Here, we present a novel method that allows fluorescence double labeling to be performed in only one incubation of 5 minutes. Fab fragments directly coupled to fluorochromes are linked to primary antibodies before these complexes are applied to sections. We quantified the influences of fixatives, labeling solutions, and incubation time on the mRNA yield and compared our method with previously proposed protocols. While tissue components, ie, vimentin and Ki67 antigen, were sufficiently stained after only 5 minutes of incubation, the new method produced a minute loss of mRNA that did not significantly differ from that of untreated sections. In contrast, incubation times of 15 and 30 minutes reduced the mRNA yield by 99.8 to 99.9%. Furthermore, incubation periods longer than 5 minutes critically affected the ratio between the target and housekeeping genes tested by factors of up to 10.6. In conclusion, the novel method described here reduces mRNA loss and potential ratio shifts to a level that does not significantly differ from that of unlabeled samples.

Animals↗
PubMed1976

Microdissection of peripheral nerve: collagen and lipid distribution with morphological correlation.

Peripheral nerve is a complex tissue composed of endoneurial fascicles surrounded by perineurium and epineurium. We separated endoneurium from peri- and epineurium in human sural nerves by "endoneurial plucking", a method of microdissection. Endoneurial contents (axons, myelin sheaths, Schwann cells, vessels, and interstitial collagen) were cleanly separated in high yield from enveloping connective tissue, by both microscopic and biochemical criteria. Most of the nerve sulfatide and unesterified sterol was found in the endoneurial fraction while most of the collagen was in the peri-epineurial fraction. This microdissection method should prove useful in biochemical investigations of peripheral nerve.

Adult↗
PubMed2001

Neuroblastic and Schwannian stromal cells of neuroblastoma are derived from a tumoral progenitor cell.

The coexistence of neuroblastic and Schwannian stromal (SS) cells in differentiating neuroblastoma (NB), and derivation of Schwannian-like cells from neuroblastic clones in vitro, were accepted previously as evidence of a common pluripotent tumor stem line. This paradigm was challenged when SS cells were suggested to be reactive in nature. The advent of microdissection techniques, PCR-based allelic analysis, and in situ fluorescent cytometry made possible the analysis of pure cell populations in fresh surgical specimens, allowing unequivocal determination of clonal origins of various cell subtypes. To overcome the complexity and heterogeneity of three-dimensional tissue structure, we used: (a) Laser-Capture Microdissection to obtain histologically homogeneous cell subtype populations for allelotype analysis at chromosomes 1p36, 11q23, 14q32, and 17q and study of MYCN copy number; (b) multiparametric analysis by Laser-Scanning Cytometry of morphology, DNA content, and immunophenotype of intact cells from touch imprints; and (c) bicolor fluorescence in situ hybridization on touch imprints from manually microdissected neuroblast and stroma-rich areas. Histologically distinct SS and neuroblastic cells isolated by Laser-Capture Microdissection had the same genetic composition in 27 of 28 NB analyzed by allelic imbalance and gene copy number. In all 20 cases studied by Laser-Scanning Cytometry, SS cells identified by morphology and S-100 immunostaining had identical DNA content and GD2-staining pattern as their neuroblastic counterparts. In 7 cases, fluorescence in situ hybridization demonstrated the same chromosomal makeup for SS and neuroblastic cells. These results provide unequivocal evidence that neuroblastic and SS cells in NB are derived from genetically identical neoplastic cells and support the classical paradigm that NB arises from tumoral cells capable of development along multiple lineages.

Adolescent↗
PubMed2002

Multiple sclerosis candidate autoantigens except myelin oligodendrocyte glycoprotein are transcribed in human thymus.

An important feature of central nervous system (CNS) immune privilege is that antigens expressed in CNS are sequestered and not available for central tolerance induction. Tissue distribution and, more specifically, thymic expression of many of the CNS putative autoantigens have not yet been clearly established in humans. We have addressed this question for the putative multiple sclerosis(MS) autoantigens alphaB-crystallin, S100beta, proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG)-alpha and MOG-beta isoforms, using quantitative RT-PCR on human thymus (total, cell fractions and microdissected specimen) and on a panel of peripheral tissues. alphaB-crystallin, S100beta and the DM20 isoform of PLP were clearly expressed in the thymus and also in selected peripheral tissues. In contrast, the expression of MOG out of the CNS was not observed. Within the human thymus, the level of CNS antigen expression was found higher in the stromal epithelial enriched cell fraction, and in microdissected samples of the medullary compartment. These results indicate that most of the antigens involved in MS are expressed in the thymus, suggesting a possible role in central tolerance. However, MOG and, to a lesser extent PLP, conform the classical concept of sequestered antigens, thus supporting the involvement of MOG in autoimmune demyelinating diseases.

Adolescent↗
PubMed2003

Gene expression pattern of laser microdissected colonic crypts of adenomas with low grade dysplasia.

BACKGROUND AND AIMS: Colorectal epithelial cells are prone to malignant transformation. Therefore, identification of differences in gene expression in the process from normal colonic crypts to adenomas with low grade dysplasia is essential for further insights into early tumorigenesis. To achieve this goal, a novel gene expression analysis strategy, screening for expressed transcripts in small histologically defined tissue samples, was performed. METHODS: First, laser mediated microdissection was used to isolate normal and adenomatous crypts from colonic cryosections. Then, nested RNA arbitrarily primed polymerase chain reaction (RAP-PCR) for differential display was performed to screen mRNA populations and to generate hybridisation probes for cDNA expression arrays. After evaluation of cDNA expression arrays, differential expression was confirmed at the protein level by immunohistochemistry. RESULTS: Evaluation of gene expression profiles of normal versus adenomatous colonic crypts of six different patients revealed, in general, dysregulation of up to 11% of all analysed genes (total number n=588): specifically, p21-rac1 was upregulated in four of six patients, mitogen activated protein kinase (MAPK) p38alpha in three of six patients, and interferon gamma receptor in three of six patients. Conversely, FAST kinase was found to be downregulated in three of six patients, p53 in three of six patients, and thrombospondin 2 in three of six patients. CONCLUSIONS: For the first time, distinct gene expression profiles of dysplastic areas within colonic adenomas, using the combination of laser mediated microdissection with RAP-PCR and cDNA expression array, were shown. In these samples, upregulation of proliferation associated genes (ras-oncogene related p21-rac1 and MAPK p38alpha) as well as downregulation of apoptosis related genes (FAST kinase and p53) most likely reflects specific alterations in adenomas with low grade dysplasia. Based on upregulation of p21-rac1 and MAPK p38alpha, activation of the MAPK pathway appears to be an early event in colonic carcinogenesis.

Adenoma↗
PubMed1990

Hair-specific expression of chloramphenicol acetyltransferase in transgenic mice under the control of an ultra-high-sulfur keratin promoter.

We have generated a transgenic mouse line by microinjection of a chimeric DNA fragment (KER-CAT) containing a hair-specific, murine ultra-high-sulfur keratin promoter (KER) fused to the coding region of the bacterial chloramphenicol acetyltransferase (CAT) gene. A 671-base pair (bp) stretch of the 5' promoter region was used to direct the expression of the CAT gene in this construct. Of the tissues tested for CAT activity in these transgenic animals only skin with growing hair, isolated hair follicles, and microdissected vibrissae showed substantial levels of activity. These are the same tissues where the endogenous ultra-high-sulfur keratin gene is expressed as shown by in situ hybridization. Furthermore, analysis of the CAT activity during the developmental stages of the hair growth cycle shows that the chimeric gene is expressed during the anagen phase of the hair growth cycle; this is the expected time during development for its expression. From these results we conclude that 671 bp of the promoter sequence from the ultra-high-sulfur keratin gene is sufficient to direct the correct development-specific and tissue-specific expression of the reporter gene construct in transgenic mice. The appropriate expression of the KER-CAT construct in transgenic mice is an important step in understanding the regulation of this gene during hair organogenesis.

Animals↗
PubMed2001

Persistent p53 mutations in single cells from normal human skin.

Epidermal clones of p53-mutated keratinocytes are abundant in chronically sun-exposed skin and may play an important role in early development of skin cancer. Advanced laser capture microdissection enables genetic analysis of targeted cells from tissue sections without contamination from neighboring cells. In this study p53 gene mutations were characterized in single cells from normal, chronically sun-exposed skin. Biopsies were obtained from skin subjected to daily summer sun and skin totally protected from the sun by blue denim fabric. Using laser capture microdissection, 172 single-cell samples were retrieved from four biopsies and analyzed using single-cell polymerase chain reaction and direct DNA sequencing. A total of 14 different mutations were identified in 26 of 99 keratinocytes from which the p53 gene could be amplified. Mutations displayed a typical UV signature and were detected in both scattered keratinocytes and in a small cluster of p53-immunoreactive keratinocytes. This minute epidermal p53 clone had a diameter of 10 to 15 basal cells. Two missense mutations were found in all layers of epidermis within the p53 clone. The presented data show that p53 mutations are common in normal skin and that a clone of keratinocytes with a mutated p53 gene prevailed despite 2 months of total protection from ultraviolet light.

Adult↗
PubMed1999

High frequency and heterogeneous distribution of p53 mutations in aflatoxin B1-induced mouse lung tumors.

Inactivation of the p53 tumor suppressor gene is one of the most frequent genetic alterations observed in human lung cancers. However, p53 mutations are more rarely detected in chemically induced mouse lung tumors. In this study, 62 female AC3F1 (A/J x C3H/HeJ) mice were treated with aflatoxin B1 (AFB1; 150 mg/kg i.p. divided into 24 doses over 8 weeks). At 6-14 months after dosing, mice were killed, and tumors were collected. A total of 71 AFB1-induced lung tumors were examined for overexpression of p53 protein by immunohistochemical staining. Positive nuclear p53 staining was observed in 79% of the AFB1-induced tumors, but the pattern was highly heterogeneous. In approximately 73% of the positively stained tumors, fewer than 5% of cells demonstrated positive staining; in the other 27%, between 10% and 60% of the cells stained positively, with staining localized to the periphery of the tumors in many cases. Single-strand conformational polymorphism analysis of the evolutionarily conserved regions of the p53 gene (exons 5-8) from AFB1-induced whole lung tumor DNA revealed banding patterns consistent with point mutations in 20 of 76 (26%) tumors, with 85% of the mutations in exon 7 and 15% of the mutations in exon 6. Identification of point mutations could not be confirmed by direct sequence analysis because bands representing putative mutations appeared only weakly on autoradiograms. This was presumably due to the heterogeneous nature of the DNA analyzed. Single-strand conformational polymorphism analysis of DNA from laser capture microdissected cells of paraffin-embedded AFB1-induced tumor tissue sections stained for p53 produced banding patterns consistent with point mutations in 18 of 30 (60%) DNA samples. Direct sequencing of the microdissected samples revealed mutations at numerous different codons in exons 5, 6, and 7. Of 26 mutations found in microdissected regions from adenomas and carcinomas, 9 were G:C-->A:T transitions, 11 were A:T-->G:C transitions, and 5 were transversions (2 G:C-->T:A, 2 T:A-->A:T, and 1 A:T-->C:G), whereas 1 deletion mutation was identified. The concordance between immunostaining and molecular detection of p53 alterations was 72% when laser capture microdissection was used versus 17% based on whole tumor analysis. The high mutation frequency and heterogeneous staining pattern suggest that p53 mutations occur relatively late in AFB1-induced mouse lung tumorigenesis and emphasize the value of analyzing different staining regions from paraffin-embedded mouse lung tumors.

Adenoma↗
PubMed1998

Clonality of B-cells in portal lymphoid infiltrates of HCV-infected livers.

Evidence has been accumulating in favour of a role for hepatitis C virus (HCV) in the pathogenesis of human lymphoproliferative disorders. HCV infection has been documented in the majority of patients with essential mixed cryoglobulinaemia type II (MC-II); in patients with HCV infection, B-cell clonal expansion have been detected in peripheral blood and bone marrow, and a high prevalence of B-cell non-Hodgkin's lymphomas has been documented. Liver biopsies in chronic hepatitis C frequently show portal lymphoid infiltrates with features of B follicles, whose clonality has not yet been investigated. This study has analysed the B-cell clonality of portal lymphoid infiltrates from 16 patients with chronic HCV hepatitis. Portal tracts showing obvious lymphoid infiltrates were microdissected from the paraffin-embedded liver tissue sections and the clonality of lymphoid B-cells was tested using a polymerase chain reaction (PCR) approach designed to identify immunoglobulin heavy chain gene (IgH) rearrangements. A successful IgH-PCR analysis was achieved in 35 lymphoid infiltrates from 11 patients (seven with the four without MC-II) and yielded a single band in 21 cases, two bands in ten cases, and three bands in four cases. Comparison of the IgH-PCR amplification bands obtained from the different lymphoid aggregates of the same biopsy revealed that they differed in size. This finding indicates that each aggregate derives from the proliferation of one or a few founder B-cells, which are not related to each other. The results obtained in patients with and without MC-II were similar, suggesting that the presence of B-cell clonal proliferations in liver biopsies is independent of the occurrence of B-cells producing monoclonal IgMk cryoglobulins.

B-Lymphocytes↗
PubMed2002

A comparison of hydraulic and laser capture microdissection methods for collection of single B cells, PCR, and sequencing of antibody VDJ.

During the development of B lymphocytes, a series of gene rearrangements assemble the sequences that encode immunoglobulin heavy and light chains (VDJ). Earlier studies of VDJ sequence diversification during expansion of cells in splenic or appendix germinal centers used hydraulic micromanipulation (HM) to collect single B cells for PCR amplification of rearranged antibody heavy and light chain genes. PCR products were directly sequenced without a cloning step. Hydraulic micromanipulation is a very tedious method. Once capability to collect single cells by laser capture microdissection (LCM) was developed, we modified previous tissue staining and fixation methods so that we could collect cells from a given stained tissue section by HM and LCM and directly compare our success rates using these two methods. Cells were alkaline lysed and after two rounds of nested PCR products were recovered and directly sequenced. Because each rearrangement of genomic DNA that occurs to form the immunoglobulin heavy-chain-encoding sequence in developing B cells is unique, this system allowed us to verify our success rate in recovering single lymphocytes from tissue sections and amplifying a single allele. The methods developed have now made LCM an efficient alternative to HM for the collection of single B cells.

Animals↗
PubMed2002

Genetic alterations in normal epithelium of colorectal cancer patients may be a useful indicator for subsequent metachronous tumor development.

BACKGROUND: We attempted to identify areas of microsatellite alterations specific to histologically normal colorectal epithelium and to clarify the correlations among those molecular events and clinicopathologic features. METHODS: We conducted a prospective observation study on 51 colorectal cancer patients. Preoperative blood and microdissected histologically normal colorectal epithelium and neoplastic tissues were collected. Microsatellite analyses with seven microsatellite loci were performed to examine the genetic potential of individual tumors and histologically normal colorectal epithelium. RESULTS: In the sporadic colorectal cancer group, p53 LOH in the neoplastic epithelium had a significant correlation with the maximum tumor diameter and the preoperative serum cancer antigen 19-9 level, but not with the depth of invasion of the primary tumor. Among the patients who had p53 LOH in the histologically normal colorectal epithelium, four additional tumors were discovered within 30 months after curative surgery. For those patients, microsatellite alterations in normal colorectal epithelium were more sensitive than tumor markers. CONCLUSIONS: For accurate LOH analysis, nonmalignant lymphocytes from blood should be used as the appropriate normal DNA sample. Focusing on the identification of high-risk patients for microsatellite alterations in histologically normal colorectal epithelium can be a useful indicator of subsequent metachronous tumor development after colorectal surgery. For accurate LOH analysis, nonmalignant lymphocytes from blood should be used as the appropriate normal DNA sample. Focusing on the identification of high-risk patients for microsatellite alterations in histologically normal colorectal epithelium can be a useful indicator of subsequent metachronous tumor development after colorectal surgery.

Biomarkers, Tumor↗
PubMed2005

Nuclear translocation of H2RSP is impaired in regenerating intestinal epithelial cells of murine colitis model.

Hepatocyte growth factor activator inhibitor type 2-related small peptide (H2RSP) is a recently identified nuclear peptide that is abundantly expressed in the gastrointestinal tract. In this study, we analyzed the expression of H2RSP in normal and injured intestinal mucosa in a murine experimental colitis induced by oral administration of 2.5% dextran sodium sulfate. Results of immunohistochemistry and in situ hybridization showed that H2RSP was expressed predominantly in the epithelium of normal intestine. Whereas H2RSP was localized in the cytoplasm of cells in the crypt, it was translocated into the nuclei of the surface epithelial cells. In injured intestine, H2RSP was detected in the cytoplasm of regenerating epithelial cells, and the nuclear translocation was impaired even in the surface epithelium. However, the mRNA level was not significantly altered in these cells by real-time reverse transcription-polymerase chain reaction using total RNAs obtained from the fractionated mucosal tissue samples prepared by laser-captured microdissection technique. On the other hand, H2RSP mRNA was significantly upregulated in the stromal cells of injured intestinal mucosa compared with those in normal mucosa, which shows cytoplasmic localization of H2RSP. These circumstantial evidences suggest that the nuclear translocation of H2RSP may be related to a signaling involved in the transition from cellular proliferation to differentiation.

Animals↗
PubMed1999

Multiple small accessory marker chromosomes from different centromeric origin in a moderately mentally retarded male.

The occurrence of more than two small accessory chromosomes (SACs) in a single individual is extremely rare. Here, we characterize six SACs found in the cells of two different tissues of a moderately mentally retarded male. Microdissection combined with regular FISH demonstrates that the SACs are ring chromosomes derived from the centromeres of different chromosomes. The SACs are often associated with the centromeres of other chromosomes. Immunofluorescence with an anti-CENP-C antibody demonstrates that the SACs contain an active centromere. A possible mechanism by which the SACs originated and their clinical relevance are discussed.

Centromere↗