Coexpression of cytokeratin and vimentin in Rathke's cysts of the human pituitary gland

A choroid plexus cyst in the fourth ventricle of a Sprague-Dawley rat

Choroid plexus cysts are rare lesions in the brain and are reported in humans and dogs. Herein, we report a choroid plexus cyst found in a 10-week-old female Sprague-Dawley rat. Histologically, a cyst measuring approximately 600 μm in diameter was found in the fourth ventricle of the brain. The cyst was lined with a single layer of flattened cells and was present in the connective tissue of the choroid plexus. Next to the cyst, a dilated tube was found with a similar morphology to the epithelium of the choroid plexus. Immunohistochemistry revealed that flattened cells lining the cyst were positive for cytokeratin and vimentin, and negative for GFAP and S-100, which is the same as in the normal choroid plexus, excluding vimentin. We diagnosed the present cyst as a spontaneously occurring choroid plexus cyst that was considered to be undergoing the epithelial-mesenchymal transition.

The excurrent ducts of the testis of the emu (Dromaius novaehollandiae) and ostrich (Struthio camelus): Microstereology of the epididymis and immunohistochemistry of its cytoskeletal systems

The volumetric proportion of the various ducts of the epididymis of the emu and ostrich and the immunohistochemistry of actin microfilaments, as well as cytokeratin, desmin and vimentin intermediate filaments, were studied in the various ducts of the epididymis of the emu and ostrich. The volumetric proportions of various ducts, which are remarkably different from those of members of the Galloanserae monophyly, are as follows: the rete testis, 5.2 +/- 1.4% for the emu and 2.4 +/- 1.8% for the ostrich; efferent ducts, 14.2 +/- 2.3% (emu) and 11.8 +/- 1.8% (ostrich); epididymal duct unit, 25.8 +/- 5.8% (emu) and 26.1 +/- 4.1% (ostrich) and connective tissue and its content, 54.7 +/- 5.8% (emu) and 60.0 +/- 4.9% (ostrich). Unlike in mammals and members of the Galloanserae monophyly, only vimentin was immunohistochemically demonstrated in the rete testis epithelium of the emu, and none of the cytoskeletal protein elements in the ostrich rete testis. The epithelium of the efferent ducts of the emu co-expressed actin, cytokeratin and desmin in the non-ciliated type I cells, and vimentin in the ciliated cell component. The ostrich demonstrated only cytokeratin in this epithelium. The ratite epididymal duct unit is different from that of mammals in lacking actin (only weaky expression in the ostrich), desmin and cytokeratin, and a moderate/strong immunoexpression of vimentin in the basal cells and basal parts of the NC type III cell in the epididymal duct unit. Immunoexpression of the microfilaments and intermediate filaments varied between the two ratite birds, as has been demonstrated previously in birds of the Galloanserae monophyly, and in mammals.

A GRFa2/Prop1/stem (GPS) cell niche in the pituitary

BACKGROUND

The adult endocrine pituitary is known to host several hormone-producing cells regulating major physiological processes during life. Some candidates to progenitor/stem cells have been proposed. However, not much is known about pituitary cell renewal throughout life and its homeostatic regulation during specific physiological changes, such as puberty or pregnancy, or in pathological conditions such as tumor development.

PRINCIPAL FINDINGS

We have identified in rodents and humans a niche of non-endocrine cells characterized by the expression of GFRa2, a Ret co-receptor for Neurturin. These cells also express b-Catenin and E-cadherin in an oriented manner suggesting a planar polarity organization for the niche. In addition, cells in the niche uniquely express the pituitary-specific transcription factor Prop1, as well as known progenitor/stem markers such as Sox2, Sox9 and Oct4. Half of these GPS (GFRa2/Prop1/Stem) cells express S-100 whereas surrounding elongated cells in contact with GPS cells express Vimentin. GFRa2+-cells form non-endocrine spheroids in culture. These spheroids can be differentiated to hormone-producing cells or neurons outlining the neuroectoderm potential of these progenitors. In vivo, GPSs cells display slow proliferation after birth, retain BrdU label and show long telomeres in its nuclei, indicating progenitor/stem cell properties in vivo.

SIGNIFICANCE

Our results suggest the presence in the adult pituitary of a specific niche of cells characterized by the expression of GFRa2, the pituitary-specific protein Prop1 and stem cell markers. These GPS cells are able to produce different hormone-producing and neuron-like cells and they may therefore contribute to postnatal pituitary homeostasis. Indeed, the relative abundance of GPS numbers is altered in Cdk4-deficient mice, a model of hypopituitarism induced by the lack of this cyclin-dependent kinase. Thus, GPS cells may display functional relevance in the physiological expansion of the pituitary gland throughout life as well as protection from pituitary disease.

[Rathke's pouch cysts: diagnosis and treatment]

We studied retrospectively a series of four patients with Rathke pouch cysts and pointed out to their clinical presentation and treatment. They all occurred with female patients. Predominant symptoms were amenorrhea, headache and visual disorders. We present a revision of the literature concerning various series of Rathke's pouch cysts. We conclude that surgery is the best therapeutical procedure and transsphenoidal approach is the best surgical technique.

Do the suprasellar neurenteric cyst, the Rathke cleft cyst and the colloid cyst constitute a same entity?

Two cases of entirely suprasellar cysts are reported. Total surgical removal was performed in both cases. Pathological and immunohistochemical profiles were consistent with neurenteric cysts, Rathke's cleft cysts or colloid cysts and was also in keeping with an endodermal origin. It is now admitted that these three kinds of cysts share similar histological and immunohistological features. We propose an hypothesis of common embryological origin from endodermal remnants.

Maintenance of cell-type-specific cytoskeletal character in epithelial cells out of epithelial context: cytokeratins and other cytoskeletal proteins in the rests of Malassez of the periodontal ligament

We have determined the patterns of synthesis of cytokeratins and other epithelial marker proteins in the "rests of Malassez" of the periodontium of rabbits and humans, by immunofluorescence microscopy of cryosections prepared from fixed and decalcified rabbit teeth with attached ligament or from manually isolated human periodontal ligaments. Proteins of the major cell structures characterizing epithelial differentiation are present in Malassez cells: a complex set of cytokeratins as well as desmosomal, hemidesmosomal and basal lamina proteins. In addition, we have shown these cytoskeletal and extracellular matrix structures by electron microscopy. The cytokeratin complement of Malassez cells was found to be highly complex, as 8 of the total of 20 known epithelial cytokeratins were detected (nos. 5, 7, 8, 14, 15, 17, 18, 19). This pattern, together with the presence of the desmosomal cadherins Dsg2 and Dsc2 and the cytoplasmic desmosome plaque-associated protein plakophilin 1, indicates that the cells of the rests of Malassez are derived from the basal cell layer of a stratified squamous epithelium rather than from simple epithelial or neuroendocrine epithelial cells. Our observations show that Malassez cells retain the major characteristics of epithelial cells throughout their differentiation from the root sheath epithelium into the rests of Malassez, even though the surface location and the polar tissue architecture that typify epithelial are lost during this process. From this study we further conclude that the specific cytoskeletal complement of the Malassez cells represents an intrinsic gene expression program that neither depends on nor causes the formation of a stratified epithelium. We also compare the specific cytoskeletal features of Malassez cells with those of other persisting epithelial residues and discuss the potential value of these findings in relation to the histogenesis and diagnostic classification of dental and periodontal cysts and tumors.

The pathologic, surgical, and MR spectrum of Rathke cleft cysts

BACKGROUND

Rathke cleft cysts (RCC) uncommonly attain large enough size to cause symptoms or warrant neurosurgical intervention, leading to difficulty in recognizing their diverse presentations.

METHODS

We retrospectively reviewed the clinical, intraoperative, pathologic, and magnetic resonance (MR) imaging findings of 16 cases seen at our institution since 1987.

RESULTS

The most unusual clinical presentation was pituitary apoplexy, although CSF-like, cholesterol containing, or hemorrhagic cyst contents most often led to intraoperative misinterpretation. Microscopic features of squamous metaplasia, lymphocytic infiltrates, tubuloracemose glands, or coexistent adenomas demonstrated the pathologic variations in these intrasellar and suprasellar cysts. The MR findings of an anteriorly displaced pituitary stalk, the presence of a posterior ledge, and T2 hypointensity were distinctive, when present.

CONCLUSIONS

Rathke cleft cysts have varied clinical presentations and sometimes confusing intraoperative and pathologic appearances. We document a new pathognomonic MR finding in these cysts of a posterior ledge sign. Our surgical approach is to open and drain cyst contents, treat the residual cyst lining with instillation of absolute alcohol, and close the floor of the sella with a bone strut.

Distribution of neurofilament proteins and peripherin in the rat pituitary gland

The distribution of neurofilament proteins and peripherin in the pituitary gland of the rat was studied with a panel of monoclonal and polyclonal antibodies recognizing different neurofilament subunits. In the posterior lobe, a dense plexus of neurofilament- and peripherin-immunoreactive fibers was seen. In the intermediate lobe neurofilament- and peripherin-immunoreactivity was seen only in nerve fibers in the connective tissue septa, while no immunoreactivity was seen in parenchymal nerve fibers. Bilateral sympathetic ganglionectomy did not affect peripherin-immunoreactivity, indicating that the peripherin-immunoreactive fibers are of central origin. In the anterior lobe, a few solitary neurofilament- and peripherin-immunoreactive fibers were observed. Western blotting confirmed the presence of 150 kD and 200 kD neurofilament proteins in the posterior lobe. No neurofilament protein was detected in the intermediate and anterior lobes. Abundant intermediate filaments were seen with electron microscopy in the nerve fibers of the connective tissue septa in the intermediate lobe. In the parenchymal nerve fibers only microtubules were seen, indicating that the lack of neurofilament immunoreactivity is due to absence of neurofilaments.

Immunohistochemical expression of human chorionic gonadotropin and P-glycoprotein in human pituitary glands and craniopharyngiomas

In order to clarify the cellular origin of craniopharyngiomas, the authors examined the distribution of P-glycoprotein (PGP) and human chorionic gonadotropin (HCG) in five normal adenohypophyses and in 23 craniopharyngiomas using peroxidase immunohistochemistry. The correlation between the expression of PGP in craniopharyngiomas and the recurrence of these tumors was also investigated. A number of pars intermedia cyst-lining cells immunostained positively for anti-PGP antibodies. A small number of adenohypophysial cells were also positive for PGP, but squamous epithelial nests were negative in all samples. However, HCG-beta was consistently demonstrated in adenohypophysial cells, pars intermedia cyst-lining cells, and squamous epithelial nests. In 11 craniopharyngiomas, the apical portion of cuboidal cells and some polygonal cells immunostained positively with anti-PGP antibodies. In four HCG-producing craniopharyngiomas, a large number of tumor cells were immunostained with anti-PGP antibodies, three of which showed a recurrence of cystic tumors. By double labeling, the coexpression of HCG-beta and PGP was demonstrated in these recurrent tumors. Accordingly, it is suggested that craniopharyngiomas produce HCG-like peptides and that craniopharyngiomas are unique squamous neoplasms arising in the sellar region from progenitor cells of a neuroendocrine lineage.

Heterogeneity in the immunolocalization of cytokeratin-specific monoclonal antibodies in the rat lung: evaluation of three different alveolar epithelial cell types

The distribution of individual cytokeratin polypeptides in the adult rat lung parenchyma was investigated by immunohistochemistry with 44 monoclonal and 2 polyclonal antibodies. Simple epithelial cytokeratins 7, 8, 18 and 19 were found to be expressed differently in alveolar and bronchial epithelial cells. Three distinct types of alveolar cells were detected according to their pattern of immunoreactivity: type II cells strongly expressing cytokeratins 8 and 18 and weakly expressing cytokeratins 7 and 19 in the cell periphery; type I cells predominantly positive for cytokeratins 7 and 19 and weakly for cytokeratin 8; and a newly defined third cell type III (alveolar brush cell) with cytokeratin 18 abundantly expressed but organized in an unusual intracellular ("globular") structure. The latter cell type failed to bind the type II specific Maclura pomifera lectin, and contained no surfactant proteins. Bronchial epithelial cells exhibited a more or less uniform staining pattern for cytokeratins 8, 18 and 19 and focally for cytokeratins 4 and 7.

Cytokeratin and vimentin heterogeneity in human cornea

The body of information on cytokeratin expression in non-epithelial and epithelioid cells is steadily increasing. In this immunocytochemical study using a panel of monoclonal cytokeratin antibodies, we regularly observed cytokeratins no. 8 and 18 together with vimentin in the corneal endothelium of the human eye, but the antibodies exhibited a heterogeneous reactivity pattern. In fetal eye specimens, cytokeratins were already present at the 10th week of gestation, and disappeared at about the 22th week of fetal development. Corneal and conjunctival epithelial cells in the same specimens usually showed uniform cytokeratin 8 and 18 expression, beside the well documented presence of corneal and squamous epithelium type cytokeratins. In 2 of our 7 cases of adults, cells coexpressing cytokeratin and vimentin were observed in the corneal epithelium. The data provide another example of modulation of cytokeratin and vimentin expression, in which simplistic rules cannot be applied.

Human intrahepatic biliary epithelial cells proliferate in vitro in response to human hepatocyte growth factor

In previous studies, intrahepatic human biliary epithelial cells (BEC) were isolated in high purity. However, these cells demonstrated only limited growth responses. Here we report that human BEC proliferate in response to human hepatocyte growth factor (hHGF), retain BEC-specific phenotype, and can be serially passaged. BEC showed dose-dependent growth in response to 0.01-100 ng/ml hHGF. The maximum S-phase labeling index reached 40% with half-maximal stimulation at 1 ng/ml. The response of cells from normal and primary biliary cirrhotic liver to hHGF was similar. Cultures were immunostained with specific antibodies and then processed for [3H]thymidine autoradiography. Proliferating cells expressed BEC-specific markers (HEA125 and CK-19), but were negative for desmin and factor VIII-related antigen. Occasional vimentin-positive cells were observed, but these were nonproliferative. In conclusion, cells responding to hHGF were clearly BEC in origin. The observation that HGF is mitogenic for BEC as well as hepatocytes has important implications. First, greater yields of intrahepatic BEC are available for subsequent studies of the pathogenesis and etiology of diseases of the biliary epithelium. Secondly, some means of regulating the cellular response to HGF in vivo must operate, in that HGF levels rise early after partial hepatectomy and yet BEC proliferate 24 h later than hepatocytes.

Co-localization of vimentin and cytokeratins in M-cells of rabbit gut-associated lymphoid tissue (GALT)

The occurrence of cytokeratins, vimentin, and desmin in the dome epithelia and adjacent non-dome epithelia in four locations of gut-associated lymphoid tissues (GALT) of adult and newborn rabbits (Peyer's patches, sacculus rotundus, caecal lymphoid patches and appendix) was studied with monoclonal antibodies, using the indirect immunoperoxidase technique. In all locations investigated in adult animals, antibodies specific for vimentin labelled (1) M-cells, which engulf intra-epithelial lymphocytes, (2) columnar epithelial cells at the base of the domes lacking an apparent contact with lymphocytes ("immature" M-cells), and (3) flat cells, which lie in the lamina propria under the dome epithelium, and which line the basal lamina with thin cytoplasmic processes. In newborn rabbits, columnar epithelial cells resembling the immature M-cells of adults were selectively stained with vimentin antibodies. In M-cells, the strongest immunoreactivity was present in the perinuclear region and close to the pocket membrane, whereas the most apical and most basal parts of the cytoplasm showed no vimentin-immunoreactivity. Enterocytes in the dome epithelium and in the non-dome epithelium were vimentin-negative. M-cells and enterocytes bound antibodies against cytokeratin peptides 18 and 19 in adult and newborn animals. Compared with enterocytes, M-cells showed less intense staining for cytokeratins. Dome epithelia and no-dome epithelia did not contain desmin-immunoreactive cells. The results suggest that vimentin is a sensitive marker for M-cells in rabbit GALT.

Co-expression of vimentin and cytokeratins in M cells of rabbit intestinal lymphoid follicle-associated epithelium

Membranous epithelial (M) cells within the follicle-associated epithelium which overlies gut-associated lymphoid tissue in Peyer's patches and of appendix have been shown by immunocytochemical staining, in rabbit, to contain both vimentin- and cytokeratin-type intermediate filaments. The specificity of vimentin immunostaining has been confirmed by blocking with purified vimentin and by immunoblotting. No evidence was obtained for the expression of vimentin in rat, mouse or human M cells. The possible significance of vimentin-expression in these specialized epithelial cells and the potential use of vimentin as a positive marker for M cells are discussed.

Cytokeratin pattern of clinically intact and pathologically changed oral mucosa

The various cytokeratin polypeptides in oral epithelia are expressed in dependence on site and formation of a stratum corneum. Certain cytokeratins occur permanently and others occasionally. In fibrous hyperplasia and Lichen ruber planus, patterns of cytokeratins did not deviate significantly from normal. In some but not all cases of squamous cell carcinoma and leukoplakia studied, marked aberrations of pattern were characterized by (i) appearance of cytokeratin No. 19, (ii) somewhat more frequent occurrence of cytokeratins Nos. 8 and 18, (iii) proteolytic modifications of cytokeratins, and (iv) partial loss of a few site-specific cytokeratins. The aberrations may be taken as additional diagnostic criteria for differentiation between non-aggressive and potentially aggressive leukoplakic lesion, even if they are not correlated with the conventional histological grading of dysplasia.

Radiologic characteristics and results of surgical management of Rathke's cysts in 43 patients

Although Rathke's cysts are a relatively common autopsy finding, rarely have they been reported as a clinical entity. Because of recent improvements in neuroradiological imaging, cystic intrasellar and suprasellar lesions are discovered often, leading to questions about proper management. Against this background, we reviewed the data from 43 patients with Rathke's cysts treated by one neurosurgeon over a 13-year period, and present the results here. The 43 patients had a mean age of 34 years, and 77% were female. Headache was the most common symptom, followed by galactorrhea, visual field loss, and hypopituitarism. Computed tomographic (CT) scans were reviewed in 20 cases, magnetic resonance (MR) images were reviewed in 15, and both CT and MR studies were reviewed in 5 cases. Although all Rathke's cysts were discrete and well-defined by both CT and MR imaging, the diversity of locations, CT attenuations, and MR signal intensity make it difficult to establish the diagnosis by radiological criteria. Forty patients underwent transsphenoidal surgery and three underwent craniotomy. There was one recurrence at 25 months requiring a second operation, and the mean follow-up period was 62 months. Seven patients had persistent headaches. For symptomatic lesions suspected to be Rathke's cysts, the recommended treatment is simple drainage of the cyst with biopsy of the wall, when this can be done safely. Follow-up imaging should be minimal for asymptomatic patients, and radiation therapy is not indicated.

Transsphenoidal management of Rathke's cleft cysts. A clinicopathological review of 10 cases

We report detailed data on 10 patients who underwent transsphenoidal microsurgical management of histopathologically confirmed Rathke's cleft cysts. Preoperatively, pituitary dysfunction was present in 90%, headaches in 80%, hyperprolactinemia in 70%, and visual interference in 40%. Computed tomography and magnetic resonance imaging had 90% and 100% sensitivity, respectively, in disclosing the lesion. The mean follow-up duration was 22 months. There was no mortality. The only morbidity was sustained diabetes insipidus in one case. Resolution or improvement in preoperative dysfunction occurred in the majority of patients: headaches in 100%, visual deficits in 75%, normalization of hyperprolactinemia in 83%, and reversal of panhypopituitarism in 33%. We conclude that Rathke's cleft cysts can be managed safely and effectively with transsphenoidal drainage and partial excision of the wall.

Expression of cytokeratins 8 and 18 in human Sertoli cells of immature and atrophic seminiferous tubules

Tissues of human testes, either normal (23 specimens of various developmental stages), or affected by pathological conditions (19 specimens of dystopia, atrophia and/or oligospermia) were immunohistochemically examined for the expression of different cytokeratins, using mainly frozen material. Cytokeratins 8 and 18 were found in varying amounts in Sertoli cells of fetal, prepubertal and senile testes and in all cases of pathological alteration. Cytokeratins were completely absent only in normal, mature seminiferous tubules. Therefore, the immunohistochemical detection of cytokeratins in Sertoli cells seems to provide a sensitive marker for immature or damaged testes.

Ber-EP4: new monoclonal antibody which distinguishes epithelia from mesothelial

A new monoclonal antibody, Ber-EP4, directed against a partially formol resistant epitope on the protein moiety of two 34 kilodalton and 39 kilodalton glycopolypeptides on human epithelial cells is described. Immunostaining of a wide range of normal and neoplastic human tissues and cell lines showed that all carcinomas and all non-neoplastic epithelial cells, except hepatocytes, parietal cells, and apical cell layers in squamous epithelia, homogeneously expressed Ber-EP4 antigen. As Ber-EP4 does not detect any normal or neoplastic non-epithelial cells, this antibody might prove valuable for the differentiation of the following (i) non-epithelial tumours from undifferentiated carcinomas; (ii) hepatocytes from bile duct cells in certain liver diseases; (iii) mesothelial cells from carcinoma cells in lung biopsy specimens; and (iv) reactive mesothelial cells from carcinoma cells in smears of serous effusions.

The expression of vimentin in epithelial cells from human nasal mucosa

The results of an immunohistological study of the normal human nasal mucosa show that there are frequently vimentin-positive cells detectable in addition to cytokeratins in the respiratory epithelium. The vimentin cells are probably ciliated and/or goblet type in origin. Furthermore, some co-expressing cells were found in basal parts of the submucous glands.

Intermediate filament expression in non-neoplastic pituitary cells

Fifty-one non-neoplastic human pituitary glands, including examples with Crooke's hyalinization or amyloidosis, were examined by an immunoperoxidase method using antibodies to keratin, vimentin, neurofilaments (NFs), glial fibrillary acidic protein (GFAP), desmin, actin, S-100 protein and a variety of pituitary hormones. It was confirmed that most of the epithelial cells in the pituitary gland express keratin immunoreactivity. These cells included endocrine cells in the anterior lobe, endocrine cells and squamous metaplastic cells in the pars tuberalis, columnar and ciliated epithelia forming follicular structures and salivary-type epithelium in the pars intermedia, and anterior lobe cells infiltrating the posterior lobe. This study also demonstrated that keratin and NFs may be co-expressed in endocrine cells in the pituitary anterior lobe, that keratin, vimentin and GFAP may be co-expressed in the epithelial cells forming cyst-like follicle in the pars intermedia, and that vimentin and GFAP may be co-expressed in folliculo-stellate cells and pituicytes. In addition, the GFAP and S-100 protein-negative high columnar epithelium in the pars intermedia tended to be positive for adrenocorticotropic hormone and melanocyte stimulating hormone, while the low columnar epithelium with the co-expression of GFAP and S-100 protein was negative for pituitary hormones.

Cell type heterogeneity of intermediate filament expression in epithelia of the human pituitary gland

In the present study we have localized immunohistochemically the intermediate filament proteins of the human pituitary gland (adenohypophysis, pars intermedia and pars tuberalis) by an indirect immunoperoxidase technique or by double immunofluorescence methods and analysed the individual cytokeratin polypeptides using two-dimensional gel electrophoresis. We found that the expression of cytokeratins in different epithelial cells of the human anterior pituitary gland was heterogeneous. Whereas the endocrine cells only expressed cytokeratins 8 and 18, the folliculo-stellate cells exhibited a reactivity for cytokeratins 7, 8, 18 and 19 as well as for GFAP and vimentin. The squamous epithelial cells of the pars tuberalis and the Ratke's cysts showed a more complex cytokeratin pattern of both squamous and simple type. Whereas in may cystic epithelial cells including the "pseudo-follicles" a triple expression of cytokeratin, vimentin and GFAP could be observed, only some basal cells of squamous epithelial nests coexpressed cytokeratin and vimentin. The differences in the intermediate filament protein distribution are discussed in the light of embryological relationships of the different parts of the human pituitary gland.

Obplacental giant cells of the domestic rabbit: development, morphology, and intermediate filament composition

Obplacental giant cells are large (less than or equal to 210 microns) polyploid cells that appear in the stroma of the pregnant uterus of the rabbit following ovoimplantation. Histological examination of a complete developmental series indicates that obplacental giant cells arise from trophoblastic knobs that have traversed the uterine epithelium during early implantation. During maturation, the cells undergo a massive (approximately 6,000%) increase in volume and penetrate deeply into the uterine stroma and myometrium, where they often become associated with blood vessels and smooth muscle cells. Giant cells at mid-gestation contain one or two large nuclei with prominent nucleoli and appear to be amitotic. They are rich in Golgi complexes, RER, SER, and cortically distributed cytoplasmic filaments, and contain intracellular canaliculi lined by microvilli. Giant cells vary with respect to the occurrence of lipid droplets, phagocytotic inclusions, lysosomal structures, and electron-dense granules. Immunocytochemistry demonstrates that the giant cells exhibit intermediate filaments related to cytokeratin and vimentin, but are negative for desmin and for an endothelial cell marker, Factor VIII-related antigen. The cells are positive for cytokeratin from their inception, but only become vimentin-positive between Days 12 and 15 of pregnancy, a change seemingly related to their detachment from epithelial tissue to take on an independent existence. Our findings indicate that the giant cells originate from obplacental trophoblast and, at maturity, exhibit cytoskeletal characteristics of isolated epithelial cells, as well as a complement of organelles suggestive of synthetic activity.

Immunohistochemical investigation of different cytokeratins and vimentin in the human epididymis from the fetal period up to adulthood

The anatomical distribution of cytokeratins and vimentin was investigated by means of immunohistochemistry in the human epididymis. Epithelial cells of the ductuli efferentes and the corpus epididymidis were positive for cytokeratins and vimentin. The expression of epithelial vimentin decreased toward the cauda epididymidis, whereas cytokeratins remained unchanged. The epithelium of the ductus deferens was negative when antibodies against vimentin were used. With monoclonal antibodies to individual cytokeratins, the presence of cytokeratins 7, 8, 18, and 19 was demonstrated histochemically throughout the epithelium of the epididymis. Monoclonal antibodies specific for cytokeratin 17 allowed immunohistochemical differentiation between the ductuli efferentes and the ductus epididymidis.

Distribution of intermediate-filament proteins in the human enamel organ: unusually complex pattern of coexpression of cytokeratin polypeptides and vimentin

We applied immunohistochemical techniques and gel electrophoresis to examine the distribution of intermediate filaments in human fetal oral epithelium and the epithelia of the human enamel organ. Both methods demonstrated that human enamel epithelia contain cytokeratins 5, 14, and 17, which are typical of the basal cells of stratified epithelia, as well as smaller quantities of cytokeratins 7, 8, 19, and in trace amounts 18, which are characteristic components of simple epithelial cells. In the external enamel epithelium and stellate-reticulum cells, most of these components appeared to be simultaneously expressed. In contrast, the parental oral epithelium was negative for cytokeratin 7, thus indicating possible "neoexpression" during the course of tooth formation. Immunohistochemical procedures using various monoclonal antibodies against vimentin revealed the transient coexpression of vimentin and cytokeratins in the external enamel epithelium and in stellate-reticulum cells during enamel development. The significance of the coexpression of cytokeratins and vimentin is discussed in relation to previous findings obtained in other normal tissues and in the light of the functional processes characteristic of these epithelia.

Vimentin expression of newly formed rat bile duct epithelial cells in secondary biliary fibrosis

The intermediate filament profile and the growth fraction of hepatocytes and bile duct epithelial cells were studied in a rat model of biliary fibrosis secondary to common bile duct ligation and scission. Strong vimentin expression was observed in epithelial cells of newly formed bile ductules, while normal liver contained only few weakly positive bile duct epithelial cells. All epithelial cells reacted with a pan-cytokeratin antibody. A monoclonal antibody specific for human cytokeratin 7 selectively reacted with both normal and newly formed bile duct epithelial cells. The intermediate filament profile of hepatocytes was constant, showing no changes during proliferation or in periportal areas adjacent to excessive bile duct formations. The proliferation-associated antigen detected by the antibody Ki-67 was present in many hepatocytes, homogeneously distributed in the lobules, but was seen only in a small proportion of the epithelial cells of the newly formed bile ducts. We conclude that vimentin may serve as an indicator for cellular reorganization in the bile duct system, and that the epithelial cells of newly formed bile ductules in this particular model of secondary biliary fibrosis were most likely to be derived from an outgrowth of the biliary duct system and recruitment of preductular epithelial cells. No morphological or immunohistological evidence suggesting a derivation from hepatocytes by ductular metaplasia or from oval cells was obtained.

Patterns of cytokeratin/vimentin coexpression in the guinea pig

The distribution of cytokeratin and vimentin in guinea pig tissues as seen by immunohistochemistry using monoclonal antibodies is described and a similar distribution pattern of coexpression of cytokeratin and vimentin in various cell types as compared to human tissues were found. The possible explanations for the unusual coexpression of both types of intermediate filaments in normal cells are discussed.

Expression of cytokeratin and vimentin in nucleus pulposus cells

With immunohistochemistry using monoclonal antibodies against intermediate filament proteins, nucleus pulposus cells were found to express cytokeratin(s) simultaneously with vimentin in fetal life and childhood. This finding adds to the series of human tissues showing coexpression of cytokeratins and vimentin. Surprisingly remnants of such cells were also found in the nucleus pulposus of adults, and a possible relationship of such cells to chordoma formation is discussed.