ISSN:0003-276X    

DOI:10.1002/ar.1092190216

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe adverse effects of formaldehyde have been discussed very emotionally in public. Anatomists, technicians in histology and embalming laboratories, as well as medical students during their dissection course are all exposed to formaldehyde, which in many situations crosses the threshold for irritation of the eyes and upper respiratory tract. There is no doubt about the acute toxic effects and the occurrence of contact dermatitis caused by formaldehyde. Studies in rats and mice using high concentrations over an extremely long period (which would not be tolerated by humans) resulted in squamous carcinoma of the nose. Epidemiologic studies on the mortality of medical personnel exposed to formaldehyde do not provide sufficient evidence of cancerogenicity. A number of recommendations will be given for defining the exact concentration in a dissecting room or laboratory and for ways of reducing formaldehyde concentrations and thus minimizing adverse health hazards. These data could initiate a discussion among anatomists, and with technicians and students, based on a sound scientific background rather than on emotion.

ISSN:0003-276X    

DOI:10.1002/ar.1092190202

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

年代:1987

数据来源: WILEY

摘要:

AbstractSecretory ameloblasts synthesize the organic matrix of enamel and secrete it at two distinct “putative secretory sites” characterized by membrane infoldings (Nanci and Warshawsky, 1984a). The antimicrotubular agent vinblastine sulphate interferes with secretion. We have examined the effect of this drug on the ameloblast secretory sites and re‐evaluated the effect on the intracellular organization of the cell by using conditions that optimize fixation, cytochemistry (ZIO), and immunocytochemistry. Associated with the disappearance of secretory granules and Golgi‐related structures from Tomes' process was the loss of membrane infoldings at secretory sites. The Golgi apparatus appeared fragmented and numerous granule clusters were found throughout the cell body. These clusters were often seen in relation to extracellular patches of material in which no crystallites were seen. Immunocytochemistry revealed the presence of enamel proteins in the protein synthetic organelles, including various granule types, in lysosomes and in the extracellular patches. These data suggest that ameloblasts under the effect of vinblastine carry on secretory activities, but the product is not routed to the usual sites. It was confirmed that membrane infoldings characterize the sites where enamel proteins are normally s

ISSN:0003-276X    

DOI:10.1002/ar.1092190203

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

年代:1987

数据来源: WILEY

摘要:

AbstractA newly established cell line of a granulocytosis/hypercalcemiainducing murine mammary carcinoma (CE mammary carcinoma) grown in serum‐free culture medium secretes factors that stimulate proliferation of granulocytes and embryonal bone cells. These cultured cells retain the ability to produce granulocytosis and hypercalcemia when they are transplanted back into mice. In culture these cells form clusters of organized cells. Studies by scanning, transmission, and freeze‐fracture electron microscope techniques reveal that these in vitro tumor cells retain the structural epithelial characteristics of mammary epithelia. They maintain cellular polarity, microvilli, and complete tight junctions. Both the in vivo and in vitro tumor cells produce viral particles with the ultrastructural features of murine mammary tumor viruses. In both in vivo and in vitro conditions, A‐type particles are present intracellularly. B viral particles are present predominantly in the intercellular spaces. Since the structural characteristics of the cultured tumor cells are consistent with the features of mammary adenocarcinomas, this is a prime culture system for studying the tumor‐derived soluble

ISSN:0003-276X    

DOI:10.1002/ar.1092190204

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

年代:1987

数据来源: WILEY

摘要:

AbstractCells of the U937 cell line were grown in delipidated calf serum for 24 and 48 hr. These cells are known cholesterol auxotrophs. When grown for 48 hr without an exogenous source of cholesterol, these cells are known to become depleted of their intracellular cholesterol stores by greater than 95%. The result is an aggregation of the cells upon mild agitation of the culture. Examination of the cell aggregate from these cultures revealed cells in various stages of altered morphology. There was a loss of microvilli from the cells. Subsequently, the Golgi complex became dilated, and secondary lysosomes and myelin figures accumulated in the cytoplasm. The cells became swollen, and the rough endoplasmic reticulum became dilated. A small percentage of the cells showed complete disintegration, with release of membrane‐bound fragments and other intercellular debris. These events suggest that the depletion of cholesterol results in the inability of the cell to produce usable membrane. As a consequence, the synthetic apparatus of the cell becomes disrupte

ISSN:0003-276X    

DOI:10.1002/ar.1092190205

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

年代:1987

数据来源: WILEY

摘要:

AbstractActin filaments, intermediate filaments, and microtubules in the odontoblasts of rat incisors were investigated electron microscopically using heavy meromyosin and taxol. Actin filaments were abundant at the periphery of the odontoblast process in the form of a network or in bundles. In a branch of the odontoblast process, longitudinally oriented actin filament bundles were found. Most actin filaments were associated with the plasma membrane via electron‐dense material which stained with tannic acid. The intermediate filaments had a diameter of 11 to 13 nm. They were distributed throughout the cytoplasm of odontoblasts. They ran lengthwise in the core of the odontoblast process, which showed a different distribution compared with that of actin filaments. Microtubules, which were disrupted after Triton X‐100 but preserved by addition of taxol, tended to be associated with intermediate filaments. Such a relation was also seen in conventional preparations. Coated vesicles, which were abundant at the periphery of the odontoblast process, were often associated with actin filaments. Therefore, it is suggested that actin filaments, in the odontoblast process at least, play a role associated with the coated vesicles at the periphery of the process, and may be involved in coated vesicle transp

ISSN:0003-276X    

DOI:10.1002/ar.1092190206

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe segmental and zonal variations in the quantitative relationships between elastic and collagen fibers within the lateral costotransverse ligaments have been investigated in the vervet monkey. The lateral costotransverse ligaments of the caudal segments have a largely elastic structure in contrast to those of the cranial segments, which are characteristically collagenous. In the transitional zone extending from the 4th through to the 6th costotransverse joints, the lateral costotransverse ligaments show a zonal differentiation into a superficial collagenous portion and a deep elastic portion. It is noted that the craniocaudal structural differentiation in the lateral costotransverse ligaments corresponds with similar changes in the vertebral ligaments in that the ligamenta flava gradually extend into the interspinous spaces from the 1st thoracic vertebra (T1) so that at T5 the ligaments occupy 50% of the interspinous space and at T7 the elastic fibers almost completely replace the interspinous ligament. Functionally, however, the regional differences in the elastic fiber content of the lateral costotransverse ligament may have no collateral relationship with the morphology of the ligamenta flava, but are conditioned by movements of the ribs. Whereas movements of the upper six joints are limited by virtue of the configuration of their articular surfaces, which are reciprocally curved, on the 7th to 10th joints the articular facets are almost flat and, therefore, allow considerable movements between the ribs and the corresponding transverse processes.

ISSN:0003-276X    

DOI:10.1002/ar.1092190207

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn an effort to further understand the basis for the changes in steroidogenesis known to occur during sexual maturation in the rat, we examined by quantitative morphologic methods the number and ultrastructure of Leydig cells in fetal rats (days 18–20 of gestation) and in rats from days 2 to 3 of age through adult. Quantitative light microscopic analyses indicated that Leydig cell number, when expressed per unit volume of testis, was very high in fetal rat testes, fell significantly in testes of days 2 to 3 rats, and subsequently rose significantly. When Leydig cell number was expressed per testis rather than per unit volume of testis, the results indicated that testes of fetal rats and rats of days 2 to 3 contained the same number of Leydig cells; after the neonatal period, significant increases in Leydig cell number per testis occurred in concert with increases in testis weight. Quantitative electron microscopic studies revealed significant differences in the ultrastructure of fetal and adult populations of Leydig cells. For example, Leydig cells of fetal and neonatal rats contained abundant lipid, whereas Leydig cells, of weeks 7 to 8 and adult rats contained little. Stereological analyses also revealed dramatic changes in smooth endoplasmic reticulum and inner mitochondrial membrane surface areas during sexual maturation, both per cell and per testis. These findings are discussed with respect to the steroidogenic capacity of the testis during sexual maturatio

ISSN:0003-276X    

DOI:10.1002/ar.1092190208

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

年代:1987

数据来源: WILEY

摘要:

AbstractPrimordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16‐mm time‐lapse filming or time‐lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed.With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: (1) The PGC produced a small pseudopodium. (2) This pseudopodium enlarged to the GR, and PGC‐substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. (3) Finally, the PGC as a whole moved toward the GR, being trailed by the process.The locomotion of the PGC on the thick collagen layer as a three‐dimensional substrate was as follows: (1) The PGC protruded a pseudopodium in the direction of the GR. (2) This pseudopodium elongated through the collagen network. (3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. (4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PG

ISSN:0003-276X    

DOI:10.1002/ar.1092190209

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

年代:1987

数据来源: WILEY

摘要:

AbstractImmunocytochemical localization of nerve growth factor (NGF) was assessed on thin sections of plastic‐embedded male mouse submandibular glands by electron microscopy. Both control and secretagogue‐stimulated glands were examined. NGF was localized in granules of both granular convoluted tubule (GCT) cells and transition cells. The latter were intermediate in morphology between GCT cells and striated duct cells. Both large and small granules were immunostained in GCT cells; however, considerable variability in immunostaining intensity was observed in both sizes of granules but especially in the small granules of transition cells. Rough endoplasmic reticulum (RER) in both cell types exhibited NGF immunoreactivity. No Golgi‐associated immunostaining was observed.Following α‐adrenergic stimulation with phenylephrine, NGF‐containing granules were sharply reduced because of extensive degranulation. Pools of immunostained secretory material suggested intracellular fusion of NGF‐containing granules. Immunostaining was also observed on membrane fragments found within large vacuoles in GCT cells. Evidence of NGF secretion after β‐adrenergic or cholinergic stimulation was less dramatic. In isoproterenol‐stimulated GCT cells there was evidence of fusion of small, apical, NGF‐stained granules. These cells also possessed heavily immunostained apical membrane blebs. Pilocarpine‐stimulated cells exhibited pleomorphic immunostained apical granules but less apical membrane immunostaining. Abundant basal lysosomes appearing in GCT cells after pilocarpine stimulation

ISSN:0003-276X    

DOI:10.1002/ar.1092190210

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

年代:1987

数据来源: WILEY