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Biomedical subjects

P Schenk

Publications and source records attributed to P Schenk.

At least 91 records · Page 5Linked to original sources
PubMed1980

Hemidesmosome morphogenesis in laryngeal carcinoma.

The ultrastructural morphology of the tumor-stromal junction of invasive squamous cell carcinoma of the human larynx is examined electron microscopically. The de novo formation of the basal lamina and hemidesmosomes in vivo is observed. The morphological sequence proceeds in four stages: (1) production of a new basal lamina; (2) extension of anchoring filaments from the plasmalemma to the basal lamina; (3) formation of the attachment plaque along the internal leaflet of the plasma membrane, and (4) development of the subbasal dense plate adjacent to and beneath the plasmalemma. This capacity in malignant keratinocytes to produce new basal lamina and hemidesmosomes is retained at certain stages of tumor invasion.

Carcinoma, Squamous Cell↗
PubMed1980

[Ultrastructure of dyskeratosis in invasive laryngeal carcinoma (author's transl)].

The occurrence and morphology of dyskeratotic cells in squamous cell carcinoma of the larynx was examined electron microscopically. An aggregation and condensation of cytoplasmic tonofilaments was observed in the dyskeratotic cells. The remnants of nuclei and other degenerated organelles were found to be intermingled with electron dense tonofilament aggregates. In some dyskeratotic cells whole desmosomes or fragmented desmosomal structures were located within the cytoplasm. The more advanced dyskeratotic cells were phagocytized by the surrounding malignant keratinocytes either in toto or in fragments. The dyskeratosis in laryngeal carcinoma is characterized by premature, abnormal, and individual keratinization of the malignant keratinocytes.

Carcinoma, Squamous Cell↗
PubMed1980

[Desmosomes in invasive laryngeal carcinoma (author's transl)].

The occurrence, morphology, and ultrastructural changes in intercellular desmosomes in squamous cell carcinoma of the larynx was examined by electron miscroscopy. The number of desmosomes in laryngeal carcinomas was decreased as compared to normal epithelia. Structural alterations in the desmosomal components were also observed. Desmosomal structures were also found within the cytoplasm of the malignant keratinocytes. These exhibited the typical features of an intercellular desmosome. These intracytoplasmic desmosomal structures may originate from the cell surface by a process of internalization of desmosome-studded invaginations of the surface membrane. The results indicate that a deficiency of desmosomes may contribute to a loss of the intercellular adhesion, a property which is known to occur in malignant epithelial tumors.

Carcinoma, Squamous Cell↗
PubMed1980

[Langerhans cells in invasive laryngeal carcinoma (author's transl)].

The occurrence and the ultrastructural morphology of Langerhans cells in invasive squamous epithelial carcinoma of the larynx was demonstrated by electron microscopy. The Langerhans cells are characterized by a deeply lobulated nucleus, dendritic cell processes, individual cytoplasmic filaments, the lack of tonofilaments, premelanosomes, melanosomes, desmosomes and other cell junctions. The particular ultrastructural criterion of Langerhans cells is the presence of the specific Langerhans granule. The occurrence of Langerhans cells in laryngeal carcinoma is presented and compared in respect to the findings in other lesions. Various aspects of the immunological function of the Langerhans cell population are also discussed.

Carcinoma, Squamous Cell↗
PubMed1980

[Ultrastructural morphology of mitochondria of malignant keratinocytes in laryngeal carcinoma (author's transl)].

The ultrastructural morphology of mitochondria in malignant keratinocytes in invasive squamous cell carcinoma of the larynx was studied electron microscopically. Structural alterations in the mitochondrial membranes, the matrix, and the cristae mitochondrales were observed. Mitochondria with multiple membrane complexes forming myelin-like figures were also found. Some malignant keratinocytes exhibited intramitochondrial osmiophilic inclusion bodies which were excluded from the mitochondrial matrix by a limiting membranous structure. Other structural changes were the occurrence of tube-like crystalloid structures in the mitochondria of certain carcinoma cells. The observations are compared to similar structures described in other cell systems. The mitochondrial alterations are discussed in terms as to their possible functional significance in carcinoma cells.

Carcinoma, Squamous Cell↗
PubMed1979

Ultrastructure of blebbing phenomenon and phagocytosis of blebs in laryngeal carcinoma.

The epithelial-connective tissue junction of invasive squamous cell laryngeal carcinoma was examined electron microscopically. The pleomorphic cytoplasmic protrusions known as blebs were observed on the lateral and basal surfaces of malignant keratinocytes. These blebs were pinched off from the malignant epithelial cells and were then observed in the connective tissue or in the intercellular spaces. After the pinching-off process some blebs were seen to be closely surrounded by pseudopods of phagocytizing histiocytic cells in the lamina propria or by adjacent malignant keratinocytes in the intercellular spaces. Since blebs are believed to be intact parts of viable cells this engulfment can be interpreted as cytophagocytosis. During cytophagocytosis the zeiotic blebs exhibited varying degrees of enzymatic digestion. The process of blebbing was discussed in respect to cellular locomotion of malignant keratinocytes during tumor invasion. This phenomenon seems to occur only in the preliminary stages of malignant tumor growth in the larynx.

Carcinoma, Squamous Cell↗
PubMed1979

The fate of hemidesmosomes in laryngeal carcinoma.

The ultrastructural morphology of the hemidesmosomes in malignant epithelial cells of invasive squamous cell carcinoma of the human larynx was studied by electron microscopy. In the more advanced carcinomas the hemidesmosomes are reduced in number or absent over extensive areas of the epithelial stromal junction. In some places the hemidesmosomes are observed to be in the process of being dislodged from their normal sites at the plasma membrane of the basal carcinoma cell. After dislodgment from the basal plasmalemma into the subepithelial connective tissue the hemidesmosomes are seen to round off with the cytoplasmic attachment plaques lying on their inner circumference. A constant feature of the detached hemidesmosomes is the absence of inserting tonofilaments. Frequently, the detached hemidesmosomes are found to be in close association with detached multilayered basement membrane material in the stroma. The detached hemidesmosome-structures appear to migrate down into the deeper layers of the connective tissue space apparently loosing their distinct ultrastructure. These observations indicate that the detachment of hemidesmosomes and their subsequent downward dermal migration may result in a loss of epithelial-stromal adherence in invasive epithelial cancer of the larynx.

Carcinoma, Squamous Cell↗
PubMed1979

[Ultrastructure of tumor-stroma junction of invasive laryngeal carcinoma (author's transl)].

The tumor-stroma junction of invasive squamous cell carcinoma of the larynx was examined electron microscopically. Polymorphic cytoplasmic protrusions (blebs) with a diameter ranging from 2--4 micron to 8--10 micron were observed on the basal and lateral surfaces of the malignant keratinocytes. A system of cytoplasmic 6--8 nm microfilaments can be seen consistently at the base of the blebs. The microfilaments possibly serve as a contractile ring during the pinching-off process of the blebs from the malignant keratinocytes. The blebs were observed at various stages of development until the pinching-off process occurred. They have varying shapes, sizes, and electron density and are plasmamembrane bounded. They contain hyaline ectoplasm, ribosome particles, a fine filamentous and fine granular material as well as some lysosomes. The blebbing phenomenon is discussed in respect to the cellular locomotion of malignant keratinocytes and interpreted as a possible temporary invasion mechanism in the preliminary stages of the tumor growth.

Carcinoma, Squamous Cell↗
PubMed1977

[Ultrastructure of hemidesmosomes in invasive laryngeal carcinoma (author's transl)].

The occurence, distribution, and ultrastructural morphological of hemidesmosomes in malignant epithelial cells of invasive squamous cell carcinoma of human larynx were studied by electron microscopy. In the more advanced invasive carcinomas, the hemidesmosomes were reduced in number or were absent as was the basement membrane over extensive areas of the epithelial-connective tissue junction. In other places structural alterations of the hemidesmosomes were seen as a defective attachment plaque on the cytoplasmic side of the internal leaflet of the plasmalemma including retraction or absence of the inserting tonofilaments. Other structural changes were found to involve the basement membrane and the associated subbasal fibrous elements of the epithelial-stromal junction. Hemidesmosome-containing areas of the basal plasma membrane were seen to invaginate and to appear to pinch off. It was observed that the detached hemidesmosomes rounded up with their cytoplasmic attachment plaque lying on the inner circumference of the vesicular structures. These vesicular hemidesmosomes contained components of their extracellular portion. The observations indicate that autophagocytosis of detached hemidesomosomes may lead to the reduction of epithelial-dermal adherence and may thus facilitate the invasion of the underlying stroma by invasive carcinomas of the larynx.

Basement Membrane↗
PubMed1977

[Cytoplasmic microfilaments in laryngeal carcinoma malignant keratinocytes (author's transl)].

The fine structure of malignant keratinocytes of invasive squamous cell carcinoma of the human larynx was studied by electron microscopy. In these malignant cells a system organized 50--70 A microfilaments is prominent in the cortical cytoplasm of the lateral and basal cell surfaces. The microfilaments are arranged either in oriented bundles or form a complex filamentous network. The bundles may lie parallel to the plasma membrane and to the long axis of the cell. The microfilaments are situated at the base of the pseudopodia-like cell processes or are found extending into microvillous cytoplasmic extensions. In some places the bundles are some associated with the plasmalemma displaying electron-dense attachment sites. Desmosomes or other types of junctional complexes invariably remain free of microfilaments. At higher magnification the individual microfilaments are seen to be interconnected transversely by a polygonal interfilamentous meshwork. Within the bundles of microfilaments focal regions of increased electron density, similar to the Z-band of sarcomeres, are observed. Organized bundles of oriented 50--70 A microfilaments do not occur in normal squamous epithelial cells of laryngeal mucosa. By analogy with various motile microfilament containing cell systems which have been shown biochemically to contain the contractile protein actin, these cytoplasmic microfilaments may be the structural elements responsible for the migratory invasive properties of malignant keratinocytes in cancer of the larynx.

Biopsy↗
PubMed1976

[The ultrastructure of dyskeratotic and dysplastic keratinocytes in oral epithelium (author's transl)].

The fine structural morphology of dyskeratotic and dysplastic keratinocytes in human oral epithelium was investigated by light microscopy as well as by transmission and scanning-electron microscopy. On the epithelial-connective tissue border, marked changes are seen in the form of polymorphous microinvasive cytoplasmic processes of basal keratinocytes, structural alterations of the basement membrane and rarefaction of the subepithelial connective tissue. Dyskeratotic keratinocytes with abnormal tonofilament configuration are phagocytized by dermal macrophages and are transported to the lamina propria. Ultrastructural signs of atypia are found in the nucleus, nucleolus, cytoplasmic organelles and mitotic apparatus. Furthermore, multiple alterations of the plasma membrane, decrease in numbers of junctional complexes and acantholytic widened intercellular spaces are observed. Intracytoplasmic lumina are formed by endocytotic invagination of desmosome-studed plasma membrane regions at the cell surface. Despite an inverse relationship between the degree of keratinization and the glycogen content of the epithelium at the subcellular level, large amounts of glycogen are found in some keratinocytes. The epithelial surface is formed by hyper-, para-, or orthokeratosis, or shows individual cell keratinization, alteration of the disintegration process and defective keratin synthesis. The ultrastructural analysis of dysplastic keratinocyte populations reveals some morphological criteria common with invasive squamous cell carcinoma, which may be important in the early diagnosis and prognosis of malignant transformation of epithelial dysplasia.

Cell Membrane↗
PubMed1975

Microfilaments in human epithelial cancer cells.

The occurence, distribution, and ultrastructural morphology of microfilaments in malignant epithelial cells of invasive squamous cell carcinoma of human oral cavity were studied by electron microscopy. The findings are compared with those in malignant oral epithelial cells of carcinoma-in-situ. In the malignant cells of invasive carcinoma, microfilaments 50-70 A in diameter are prominent in the cortical cytoplasm of the lateral and basal cell surfaces, adjacent and parallel to the plasma membrane, and extending into cell processes and microvillous extensions. Additional microfilaments are found to run from the peripheral cytoplasm to the perinuclear region. The microfilaments are aggregated into bundles aligned parallel to the long axis of the cell and display foci of increased electron density. They also tend to be aggregated into complex polygonal arrays. These microfilaments are similar in organization, concentration and ultrastructural architecture to those of various other nonmuscle cells, where they are thought to be capable of contraction and associated with cell motility. The presence of a microfilament system believed to be associated with contractile and motile cell processes may be an important characteristic of malignant cells of invasive tumors. The lack of abundant organized microfilaments in malignant cells in the absence of tumor invasion, and the presence of a prominent microfilament system in cells of invasive tumors, suggest that the microfilaments are related to the invasive properties of malignant tumor cells.

Basement Membrane↗
PubMed1975

[Desmosomal structures in the cytoplasm of normal and abnormal keratinocytes (author's transl)].

The occurrence of intracytoplasmic desmosomes in normal, hyperplastic, and hyperkeratotic epithelia, in carcinoma-in-situ and in invasive carcinoma of the human oral cavity is demonstrated by electron microscopy. The mechanism for formation of these structures by invagination, separation and by intracytoplasmic incorporation of plasma membrane-desmosome-complexes are described in various oral epithelia, and other possible mechanisms are discussed. Intracytoplasmic desmosomes may occur in normal and pathological keratinocytes of all layers of the oral epithelium. Their ultrastructure in the peripheral cytoplasm is similar to that of the regular desmosomes on the cell surface. However, as they migrate centripetally, they show signs of degeneration, suggesting dissolution by lysosomal enzyme systems. Various surface membrane alterations involved in the formation of intracytoplasmic desmosomes may lead to a reduction of plasma membrane material and of desmosome structures and to defective intercellular adhesion. The intracytoplasmic incorporation of desmosome structures is a ubiquitous phenomenon exhibited by epithelial keratinocytes under certain physiological or pathological conditions.

Carcinoma in Situ↗
PubMed1975

[The ultrastructure of papillae filiformes of human tongue (author's transl)].

The fine structural morphology of the filiform papillae of the human tongue is investigated by transmission and scanning electron microscopy. Separation of the epithelium from the connective tissue by treatment with trypsin allows the demonstration of the three-dimensional structure of the primary and secondary connective tissue papillae and of the papillary epithelium. The distal surface of each primary connective tissue papilla is studded with secondary connective tissue papillae. Their lamellated surface structure corresponds with a complex system of cytoplasmic processes of the basal epithelial cells. The complicated surface architecture of the epithelial-connective tissue junction may suggest a close structural and functional relationship between the two types of tissues. There are two distinct cell populations forming the epithelial papilla, which differ in ultrastructural morphology from the basal cell layer to the surface of the epithelium. A dual pattern of keratinization, phylogenetically analogous to the hard and soft keratinization in rodent tongues, is found also in filiform papillai of the human tongue. The final product of epithelial differentiation is a type of keratin different from that in epidermal keratinocytes and in other regions of the oral cavity. The variability in size, shape and association with other organelles suggests the heterogenous nature of lingual keratohyaline granules. The predominance of Odland bodies of lamellated or of spoke type varies with the degree of keratinization of different regions of the papillary epithelium.

Biopsy↗
PubMed1975

[Principals of hormone substitution in thyrectomized patients with carcinoma of the thyroid gland (author's transl)].

The substitution of thyrectomized patients with carcinoma of the thyroid with L-thyroxin has advantages compared to a substitution with triiodothyronine, 200 mug T4/d are sufficient to obtain a negative TRH test in most patients. For security it is suggested to performe a general substitution of these patients with 300 mug T4/d. This dose is very well tolerated. To high doses of substitution cause a "damage" of the thyreotrop in a part of the patients. This is demonstrated by a transient thyreotropic insufficiency after withdrawal of the substitution. The results demonstrated here suggest that the central suppression of TSH secretion is better correlated with plasma T4 than plasma T3 levels.

Humans↗