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F B Merk

Publications and source records attributed to F B Merk.

At least 37 records · Page 2Linked to original sources
PubMed1982

Ultrastructural changes in surface topography, glycocalyx and plasma membrane interior of tumor cells during exocytosis of mucus.

Plasma membrane changes, which occur during exocytosis, were studied by electron microscopy in six specimens of primary mucous-producing adenocarcinoma of human urinary bladder. The luminal surfaces of non-secretory neoplastic cells display numerous microvilli, which have a thick ruthenium red-positive glycocalyx. Neoplastic secretory cells have a smooth luminal surface with relatively few microvilli. The glycocalyces of these cells are thin, especially at locations where the plasmalemma and underlying mucous granule membrane are in close apposition. The fused membranes often bulge into the lumen forming distinct protuberances. In freeze-fracture replicas the protuberances appear devoid of 7-8 nm intramembrane particles. Our results suggest that there are differences between non-secretory and secretory neoplastic cells that are expressed in surface topography, glycocalyx and internal membrane structure. Secretion-induced changes observed in plasma membranes of the neoplastic cells closely resemble changes that are known to occur in the plasmalemma of normal secretory cells.

Adenocarcinoma↗
PubMed1981

Heterogeneous distribution of filipin-sterol complexes in nuclear membranes.

Filipin, a sterol-specific polyene antibiotic, has been shown by electron microscopy to form complexes in membranes of mouse urinary bladder cells. Following instillation of a glutaraldehyde-filipin-dimethylsulfoxide solution into the bladder lumen, filipin-cholesterol complexes appear as membrane corrugations in thin sections and as 20-25 nm protuberances and depressions on PF and EF faces in freeze-fracture replicas. The complexes are observed in plasmalemma, Golgi membrane, rough endoplasmic reticulum and nuclear membrane of five different cell types (urothelial, endothelial, mesothelial, smooth muscle and fibroblasts). In the present report, we direct particular attention to the localization of numerous filipin-cholesterol complexes present in the nuclear envelopes of these cells. Our results suggest that enrichment of cell membranes with cholesterol occurs at an earlier stage in the flow-differentiation process than previously suspected. In addition, the unequal distribution of complexes in favor of the outer nuclear membrane suggests that it has a higher cholesterol content than the inner membrane.

Animals↗
PubMed1981

Primary adenocarcinomas of the human urinary bladder: histochemical, immunological and ultrastructural studies.

Neoplastic and non-neoplastic tissue specimens from ten patients with primary adenocarcinoma of the urinary bladder were examined. Most of these tumors were associated with either foci of transitional cell carcinoma and/or with glandular metaplasia of the bladder epithelium. The mucin produced by the neoplastic cells was PAS, alcian blue, mucicarmine, PB/KOH/PAS, and RPB/KOH/PAS-positive. ABH isoantigens of these tumors were not always deleted. Ultrastructurally, the neoplastic cells resembled goblet cells. Their plasma membrane had numerous microvilli with prominent glycocalyx. Proliferation and attenuation of tight junctions were noted. The gap junctions were few and small. Two types of desmosomes were found. The ultrastructural features of the neoplastic cells were attributed in part to the malignant transformation and in part to the direction of their differentiation. We have not observed any distinctive morphologic, histochemical, immunologic or ultrastructural features that might be diagnostic for these adenocarcinomas.

Adenocarcinoma↗
PubMed1980

Effects of estrogen and androgen on the ultrastructure of secretory granules and intercellular junctions in regressed canine prostate.

Epithelial cells in the prostate of the castrated or hypophysectomized dog were studied by thin-section and freeze-fracture electron microscopy to determine in vivo responses to estradiol-17 beta 17-cyclopentylpropionate (ECP) and testosterone cyclopentylpropionate (TCP). Particular attention was given to changes in specific organelles and intercellular junctions that might reflect hormone action. The few secretory granules that remain in the regressed epithelium (vestigial granules) serve as markers of prior androgen responsiveness. Pharmacologic doses of ECP caused regressed glandular cells to acquire a novel phenotype. Characteristic features of these estrogen-modified glandular (EMG) cells are newly formed secretory granules and tonofilament bundles that coexist with vestigial granules, thus demonstrating bipotentiality of response. Glandular cell-tight junctions appear unaltered by the endocrine manipulations. Although EMG cells have squamous cell features, tight junctions remain intact. Desmosomes in the canine prostate are dimorphic and are classified 70F and 100F according to the width of the filaments that converge on the dense plaques. In intact dogs, 100F desmosomes are associated with basal-reserve cells, whereas only the 70F variety is found between glandular cells. TCP treatment does not alter this distribution. Following ECP administration, both 70F and 100F desmosomes are present between EMG cells. The coexistence of newly formed secretory granules and tonofilaments of 100F desmosomes in the same EMG cell represents estrogen-induced bidirectional differentiation. Our findings indicate that androgens and estrogens are individually capable of controlling the expression of secretory granules and desmosomes. In intact animals, male and female sex hormones may act in concert to direct epithelial cell differentiation of the prostate.

Androgens↗
PubMed1980

Gap junctions in the myometrium of hypophysectomized estrogen-treated rats.

Gap junctions, which appear in the myometrium at parturition, are believed to permit the flow of ions between smooth muscle-cell interiors thereby facilitating coordinated contractions. Gap junctions are not observed in thin-sectioned myometrium of immature hypophysectomized rats. Following estrogen administration, numerous gap junctions are present suggesting that this hormone is capable of promoting electrotonic coupling in uterine smooth muscle.

Animals↗
PubMed1978

Bipotentiality of response to sex hormones by the prostate of castrated or hypophysectomized dogs. Direct effects of estrogen.

Prostatic response to administered estradiol-17beta 17-cyclopentylpropionate (ECP) was studied in castrated or hypophysectomized dogs. Ultrastructural investigation identified two types of epithelial cells, squamous and modified glandular, that resulted from estrogen action. Squamous cells, which predominated, appeared to evolve from basal reserve cells. Estrogen-modified glandular cells have features attributable to estrogen and previous androgen stimulation. Thaw-mount autoradiography of explants located radiolabeled estrogen in prostatic epithelium and stroma of normal and ECP-treated animals, suggesting a role of estrogen in prostatic homeostasis. Epithelium from ECP-treated dogs incorporated 3H-thymidine, indicating that estrogen promotes DNA synthesis in these cells. Greatly enhanced conversion of radiotestosterone to 4-androstene-3,17-dione, with sharply decreased formation of 5alpha-reduced hydroxylation products, and attendant elevation in estradiol-17beta oxidoreductase activity are metabolic markers attributable to the induced squamous and responding stromal cells. The duality of prostatic response to sex hormones is apparent from observations that estrogen stimulates regressed glandular epithelium which had undergone androgen-mediated differentiation before ablation.

Animals↗
PubMed1975

Cytoplasmic inclusion bodies in superior rectus muscle of the eye.

Cytoplasmic inclusion bodies are found in fibers of superior rectus muscle of the eye. They occur in middle-aged and old individuals dying with various unrelated diseases not affecting muscle and in patients with myotonic dystrophy. With light microscopy they can be observed in fibers with pathologic changes, and with electron microscopy they appear to be associated with crystals of probable viral origin. It is suggested that cytoplasmic inclusion bodies in superior rectus muscle are the result of viral activity and may represent an incidental viral infection of the senescent period.

Aged↗