摘要:

AbstractThe rounding up of mitotic human Chang liver cells in monolayer culture was studied quantitatively. It was surprising to find significant reduction in cell surface area considering that endocytosis has been demonstrated to be at a complete standstill in M phase. Uptake studies using impermeant BCECF (2′,7′‐bis(2‐carboxyethyl)‐4(5)‐carboxyfluorescein free acid) pH indicator and particulate neutral red dye in aqueous buffer showed preferential internalization into mitotic cells in direct contrast to expectation since interphase cells do not have arrested endocytosis. However, infolded plasma membrane ruffles and internalized extracellular material were demonstrated in prophase cells, much like those seen in interphase rounding via the induction of intracellular alkalinizations. Raised intracellular pH (pHi) is a universal and consistent finding in M phase cells. Despite cessation of small pit endocytosis, it remains possible for plasma membrane internalization to be a causal factor in the observed surface area reduction in mitotic rounding. © 1993 Wil

ISSN:0003-276X    

DOI:10.1002/ar.1092350202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSince conventional chemical fixation may extract tissue components and thus alter structural organization, cryofixation was used to reexamine the ultrastructure of three thick basement membranes: lens capsule, Reichert's membrane, and Engelbreth‐Holm‐Swarm (EHS) tumor matrix, and two thin basement membranes, those of epididymis and seminiferous tubules. Cryofixation was achieved by slam freezing followed by either freeze substitution in dry acetone containing 1% osmium tetroxide and 0.05% uranyl acetate or freeze drying in a molecular distillation dryer. The results by both procedures demonstrate that thick basement membranes and the lamina densa of thin basement membranes are composed of a network of anastomosing strands referred to ascords. The cords vary in density and distinctiveness, but their thickness averages 3 to 5 nm in every tissue examined. The spaces separating the cords vary within wide limits, but their mean diameter is ∼15 nm in every case. Two other common features are (1) the presence within the network of a few 1.5–3.0‐nm‐thick filaments and (2) 4.5‐nm‐wide sets of parallel lines referred to asdouble tracks. When these results are compared with those previously described after conventional fixation, no significant difference is observed in either the cord network or the associated filaments and “double tracks.” However, in the thin basement membranes processed by cryofixation, the lamina densa is in direct contact with epithelial cells, whereas, after conventional fixation, the lamina densa is separated from the epithelial cells by a pale layer referred to aslamina lucidaorlamina rara. Immunogold labeling of three basement membranes after cryofixation and freeze substitution in acetone containing 0.3% glutaraldehyde yields strong reactions for laminin, type IV collagen, and heparan sulfate proteoglycan. Comparison with previous results indicates that conventional formaldehyde fixation adequately preserves laminin and type IV collagen but causes the loss of some proteoglycan. It is concluded that, except for this loss and the absence of lamina lucida in cryofixed thin basement membranes, the morphological and antigenic features obtained after cryofixation are similar to those observed in the past after conventional fixation. ©

ISSN:0003-276X    

DOI:10.1002/ar.1092350203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe investigated the relationships among bone mass, bone cell activities, and exercise level in 20 healthy 61–77 year old male volunteers divided into three groups according to the time they physically trained per week: nine subjects training less than 3 hr/week, five subjects between 3 and 6 hr/week and six subjects more than 6 hr/week. Physical performance was evaluated by Vo2max (ml min−1kg−1). After tetracyline double labeling, iliac crest biopsy was obtained from each subject. The longer the physical activity, the higher the Vo2max. Subjects exercising between 3 and 6 hr/week revealed higher adjusted appositional and bone formation rates than all the others; mass and structural parameters also showed higher (nonsignificant) values. For the whole population V̇o2max appeared negatively related to cortical thickness, cancellous bone volume, and trabecular thickness. These alterations were accompanied by increased cancellous bone turnover; this was evidenced by an increase in activation frequency and in resorption and formation rates as V̇o2max increased. The bone remodeling periods tended to decrease also. Whatever the bone turnover rate, subjects were in steady state as far as their bone balance was concerned. Relationships between V̇o2max and mineral apposition rate on the one hand and V̇o2max and resorption surface on the other hand were best fitted by a quadratic model, suggesting a possible nonlinear effect of physical training on bone mass. We hypothesize that there is a threshold (6 hr/week) determining different effects. Adjustment of bone mass and trabecular arrangement were completed at time of biopsy and reflected probably past and transient bone imbalance. Other studies are needed to corroborate this assumption. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092350204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractDuring growth the muscles of mastication alter their lines of action. Research on long bones indicates that the apparent migration of muscle attachments is due to the movement of the periosteum relative to the underlying bone. To assess whether the pig masseter muscle follows the periosteum during growth, implants of titanium granules in a gelatin matrix were placed simultaneously in various parts of the masseter muscle and its periosteal and bony attachments. Growth movements of these tissues were followed radiographically for 2 months. Granule position was verified histologically. Periosteal movement was the dominant growth process at the insertion of the masseter. All implants migrated caudally relative to the mandible. However, a strong position effect was seen dorsoventrally: implants placed high in the ascending ramus migrated dorsally as well as caudally; low implants migrated only caudally. This differential migration, ascribed to the influence of the condyle, accounts for the increasing horizontal orientation of dorsal fibers. A similar differential was seen along the rostrocaudal axis of the ramus. In contrast to the insertion, the origin of the masseter from the zygomatic arch shows no periosteal movement. Rather, the entire bone‐muscle complex becomes displaced by sutural growth, leading to increasing vertical orientation of the masseter. Thus two different aspects of skull growth are responsible for the change in muscle anatomy. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092350205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of androgen deprivation and estrogen stimulation on rat coagulating gland were determined by immunohistochemistry and morphometric quantification of different tissue compartments. In castrated or estrogen‐treated or estrogen‐treated castrated animals, the reduction of the glandular lumen is the most obvious morphological alteration, which is accompanied by an increase in stromal tissue, especially within the lamina propria. Regressive changes occur most rapidly in castrated animals (already by the end of the first week), slower in estrogen‐treated castrated animals, and still slower in estrogen‐treated normal animals. In castrated animals, epithelium shows a reduction of rough endoplasmic reticulum, loss of secretory blebs, and a decrease of cell size and immunoreactivity for secretory transglutaminase. The reduction of glandular lumen results from an impressive increase in connective tissue of the lamina propria. Smooth muscle cells become atrophic in castrated animals, less so in estrogen‐treated animals and in castrated estrogen‐treated animals. A relative increase in thickness of the smooth muscle cell layer occurs in all experimental groups and is most obvious in estrogen‐treated normal animals. The proportion of myofilament and intermediate filament proteins (smooth muscle‐specific actin and desmin immunoreactivities) remains nearly unaltered in these cells after hormonal challenge. A redistribution of intermediate filaments occurs forming thicker bundles within the cells. No indication for increased mitotic activity of estrogenized smooth muscle cells has been found. After castration, and after estrogen treatment, the fibroblasts and the smooth muscle cells, respectively, appear responsible for the architectural changes within the coagulating gland. Reactions of the stroma are differentially regulated after estrogen treatment and androgen deprivation. No indication for increased biosynthetic activities of smooth muscle cells has been observed in any of the experimental conditions. © 1993

ISSN:0003-276X    

DOI:10.1002/ar.1092350206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe cysteine endopeptidase cathepsin B (CB) can degrade basement membrane (BM) proteins (such as laminin, type IV collagen, and fibronectin) at both acid and neutral pHs suggesting that CB has a role in tumor invasion and distant metastasis. The distribution and intensity of CB protein localization vary in normal prostate, benign prostatic hyperplasia (BPH), and neoplastic prostate. These considerations have led us to examine whether the distribution of CB localization in malignant and normal cells is due to storage or active synthesis of CB. In the present study, we examined the localization patterns of CB at the mRNA level in normal prostate, BPH, and well to moderately differentiated neoplastic prostate, focusing on invasive groups of cells and invasive edges of malignant tumors. We used a 25‐base biotinylated oligonucleotide CB cDNA “sense” probe to localize CB message in prostate samples obtained from radical prostatectomies. We have determined that CB is actively synthesized by the epithelia of normal, hyperplastic, and neoplastic prostate including some invasive cells in the invasive edges. In both normal and BPH, CB mRNA was localized predominantly in acinar basal cells with some localization in cuboidal/columnar cells. In contrast, in neoplastic prostate, CB mRNA was localized predominantly in columnar cells and in groups of invasive cells and invasive edges. Thus, in malignant prostate the predominant cell types expressing CB differed from those of the normal prostate and BPH. Analysis of CB mRNA localizations indicated a heterogeneity in staining distribution in prostate cancer with some invasive groups of cells and invasive edges exhibiting CB mRNA and others exhibiting little or no reaction products. Using CB as a marker, we have been able to define invasive edges and invasive cells which may be actively involved in tumor progression. The potential ability to distinguish between malignant and nonmalignant foci and edges via localization of CB within the prostatic extracellular matrix may improve diagnosis and treatment of some higher grade tumor patients. This is especially important since histologic differentiation patterns of moderately to poorly differentiated human prostatic adenocarcinoma often do not differentiate between malignant and nonmalignant foci and edges in predicting aggressive behavior and course of the disease in patients. This is the first localization of cathepsin B mRNA in human prostate and its tumors. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092350207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo major morphogenetic events, epithelial conversion and fold formation, occur in the proximal rat colon during the last week of gestation. To evaluate the role of actin microfilaments in these two developmental processes, explants from the proximal colon of 19 day fetal rats were cultured in the presence of vehicle (0.1% dimethylsulfoxide), 0.1, 1.0, or 10 μg/ml of cytochalasin D (CD) for 24–48 hr. Explants as well as 19, 20, and 21 day in vivo controls were prepared for light, fluorescence, and electron microscopy. The distribution of actin filaments was determined by rhodamine‐conjugated phalloidin binding and ultrastructural analysis of tissue fixed in the presence of tannic acid. Prior to fold formation, phalloidin binding was enhanced along the entire epithelial‐mesenchymal interface. At the onset of fold formation, focal areas of intense fluorescence appeared at irregular intervals along the base of the stratified epithelium. Within 1 day, these focal intensities were localized at the apex of small forming folds. Additional changes occurring at the epithelial‐mesenchymal interface in association with fold formation included: (1) ruffling of the previously smooth basal lamina, (2) a shape change in the subjacent mesenchymal cells from elongate to cuboidal along with the appearance of numerous processes abutting the basal lamina, and (3) a unique orientation of the associated collagen fibrils in some presumptive folds. Fold formation was inhibited in>93% of explants cultured in the presence of 1.0 μ g/ml CD. These explants appeared to be arrested precisely at the onset of fold formation. Epithelial conversion was also incomplete in these explants. These findings indicate an active role for actin in both fold formation and epithelial conversion. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092350208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractDose‐dependent tension curves were recorded from the in vitro toad aortas by administration of endothelin‐1 and sarafotoxin‐S6b. The maximal contractile tensions by both drugs were evoked at a 10−8M concentration. By a single dose application (10−8M) of endothelin‐1 and sarafotoxin‐S6b to both endothelium‐preserved and denuded vessels, the induction of the endothelium‐dependent vasocontraction occurs after 2 min of administration.Ultrastructural changes of Weibel‐Palade bodies such as decrease in electron density, swelling with a wide peripheral halo, and expulsion of their contents in a manner of exocytosis become evident within 2 min after administration of these drugs. These findings indicate that some vasocontractile substances in Weibel‐Palade bodies are extracellularly discharged by endothelin‐1 and sarafotoxin‐S6

ISSN:0003-276X    

DOI:10.1002/ar.1092350209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe relation between vascular development and translocation of the splanchnic mesodermal layers was studied in presomite to 20‐somite quail embryos by scanning electron microscopy. In addition, serially sectioned embryos were stained immunohistochemically with monoclonal antibodies (αQH1 or αMB1) specific for endothelial and hemopoietic cells.By the formation of the foregut the anterior borders of the two splanchnic mesodermal layers of a presomite embryo are translocated to the lateral and ventral sides of the foregut and fuse in the ventral midline of a 4‐somite embryo. Meanwhile the splanchnic mesoderm differentiates into a splanchnic mesothelial layer and a plexus of endothelial cells, facing the endoderm.From 4 somites onward the foregut is covered by a single endothelial plexus. At first the endothelial precursors bordering the anterior intestinal portal and those in the area of the ventral mesocardium lumenize, subsequently giving rise to the endocardium of the heart tube. Hereafter, the pharyngeal arch arteries and the dorsal aortae develop from the remaining precursors. During formation of the pharyngeal arches, the pharyngeal arch arteries maintain their connections with the splanchnic plexus through the developing ventral pharyngeal veins.After disappearance of the dorsal mesocardium, the midpharyngeal endothelial strand, which is a longitudinal strand of proendocardial cells, remains connected to the foregut. This strand will contribute to the formation of the pulmonary venous drainage into the left atrium.A bilateral accumulation of cardiac jelly developing between the promyocardium and proendocardial plexus only suggests that the heart develops from two tubes. The proendocardial layer, however, is not divided by the ventral mesocardium but initially forms just one endocardial heart tube. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092350210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTilapia (Oreochromis niloticus), 21 g average body weight, were divided into two groups. A group was maintained in fresh water, whereas another group was adapted for 2 weeks to 20% salt water. Among the latter, fishes were injected every 2 days for a week with tilapia prolactin (ti‐PRL I). Gills were prepared for electron microscopy in order to determine the types and surface areas of chloride cells in each experimental condition. Two types of chloride cells, the α and β cells were easily distinguished on the basis of their location and ultrastructural features in the gills of freshwater fishes, while only one type of cell, the saltwater α cells presumably derived from the transformation of the freshwater α cells, were encountered in saltwater adapted animals. After PRL injection ofsaltwater adapted fishes, small chloride cells, which displayed ultrastructural features similar to those of β cells in freshwater tilapia, reappeared in interlamellar regions of the gills. In the same experimental conditions, the voluminous saltwater α cells showed a tendency to resume ultrastructural features more characteristic of the freshwater α cells from which they were derived. These observations tend to indicate that prolactin behaves as a “freshwater adapting hormone” and that β cells are specifically involved in fish adaptation to freshwater living conditions. © 1993 W

ISSN:0003-276X    

DOI:10.1002/ar.1092350211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY