摘要:

AbstractThe present article was written as an attempt to understand the position of animal rights groups, to stimulate scientists to define their own positions, and to encourage scientists to interpret their use of animals to the rest of society. The article attempts to generate a statement of practices that might be useful in experiments that utilize animals in research. The statement is an extension of the three R's originally proposed by Russell and Burch (W.M.S. Russell and R.L. Burch [1959]: Principles of Humane Experimental Technique, Springfield, IL, Charles C. Thomas) into four R's: refinement, reduction, replacement, and review.

ISSN:0003-276X    

DOI:10.1002/ar.1092190302

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

年代:1987

数据来源: WILEY

摘要:

AbstractRecent biochemical and morphologic evidence supports the concept that hypertrophic chondrocytes of growth plate cartilage are fully viable cells that play a major functional role in controlling endochondral ossification. However, events associated with chondrocyte death remain unknown. In this study we assess the viability of terminal hypertrophic chondrocytes in situ in an organ culture system viewed simultaneously with rectified Nomarski interference contrast optics and with vital staining under fluorescence optics. Second, we use two methods of optimal chemical fixation at the ultrastructural level to define morphologically distinct stages of the terminal hypertrophic chondrocyte, which we interpret as the stages preceding chondrocyte death. An analysis of serial sections at the light microscope level showed that terminal chondrocytes were found, with different probabilities, in three morphologically distinguishable stages. Seventy‐five percent of all profiles were fully hydrated cells with an intact plasma membrane making direct contact with the pericellular matrix, a morphology identical to that of living terminal chondrocytes viewed in Nomarski optics. Approximately 1% of terminal chondrocytes, while still in a fully hydrated state, consistently made a direct asymmetrical contact of the plasma membrane with the last transverse septum. In 24% of the profiles, terminal chondrocytes were found as condensed cells that retained their attachment to the last transverse septum. The stages were not characteristic of chondrocytes positioned more proximally in the growth plate. We hypothesize that a condensed morphology eventually characterizes each hypertrophic chondrocyte, and we relate these observations to current hypotheses concerning the mechanism of death of hypertrophic chondrocyte

ISSN:0003-276X    

DOI:10.1002/ar.1092190303

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

年代:1987

数据来源: WILEY

摘要:

AbstractEnddosteal spaces of alveolar bone communicate with the periodontal ligament and may contribute to its cell populations. We examined cell proliferation and migration in endosteal spaces and in the periodontal ligament contiguous with these spaces. Radioautographs of mouse mandibular molar were prepared from animals pulse‐injected with3H‐Tdr and sacrificed in groups of 22 mice each at 1 h, 1, 3, and 7 d after labeling. Cell counts, labeling indices, grain counts, and progenitor cell ratios were determined. The data indicate that endosteal spaces are enriched with3H‐Tdr‐labeled progenitor cells whose progeny rapidly migrate out of the compartment. The periodontal ligament contiguous with the endosteal spaces exhibited 5 times as many labeled cells as other sites in this tissue. Thickened areas of cementum were coincident with the openings of endosteal spaces in over 64% of observations. The data are consistent with the hypothesis that cells migrate from endosteal spaces into the periodontal ligament and there express the phenotype for osteoblasts or cement

ISSN:0003-276X    

DOI:10.1002/ar.1092190304

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe pattern of postnatal growth and development of skeletal muscle in mdx mice was studied by light and transmission electron microscopy and by autoradiography and was compared with that in their normal age‐matched controls at 4 and 32 weeks of age. The muscle weights of both the extensor digitorum longus (EDL) and soleus muscles of mdx mice were significantly greater than those in control mice at both ages. Body weights of male and female mdx mice were also increased over controls up to 12 weeks of age. At 4 weeks, both the EDL and soleus muscles exhibited focal areas of degeneration, necrosis; and regeneration of centrally nucleated extrafusal fibers resulting in a wide range of fiber sizes. By 32 weeks, the majority of fibers in both muscles were centrally nucleated, and focal areas of recent regeneration were observed. By electron microscopy, the course of macrophage infiltration into areas of degenerating fibers and the ongoing regeneration of myofibers within redundant cylinders of external lamina were noted. This pattern was frequent in 4‐week‐old mdx muscles and was present to a lesser degree at 32 weeks. A notable lack of both adipose tissue infiltration and fibrotic change in the endomysium were observed in muscles at both ages. Autoradiograms of muscles from 4‐week‐old mdx mice injected with tritiated thymidine showed an increased proportion of labeled sublaminal nuclei at 24 and 48 hours after injection compared to controls. At 32 weeks of age, labeling of nuclei in muscles of mdx mice was also greater than in controls, but was reduced compared to muscle labeling in 4‐week‐old mdx mice. The observed features of mdx muscle tissue suggest that this animal model is more applicable to the study of regeneration dynamics than to Duchenne‐type human mus

ISSN:0003-276X    

DOI:10.1002/ar.1092190305

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe granular columnar epithelial cell of the equine dorsal large colon has been studied by transmission electron microscopy and X‐ray microanalysis. Particular attention was focused on nuclear bodies commonly observed as central clusters of spherical, electron‐dense inclusions within the nucleus. Ultrastructural morphology as well as X‐ray microanalysis spectra reveal great similarity between colonic nuclear bodies and the numerous small granules of the apical cytoplasm in these epithelial cells. X‐ray spectra of these cells were distinct from those of goblet cell mucous granules and mast cell granules. No evidence was found indicating transit of nuclear body granules through the nuclear envelope, or for morphologic association with the nucleoli. Of the diverse types of nuclear bodies previously reported in other species, equine colon nuclear bodies morphologically most closely resemble those seen in rabbit adenohypophysis. Colon epithelial cell nuclear bodies are likely identical to equine small intestine nuclear bodies, but their origin and role remain

ISSN:0003-276X    

DOI:10.1002/ar.1092190306

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn addition to lymphocytes, macrophages, and epithelial cells, the bursa medulla possesses a cell we have named the secretory cell. The secretory cell, which makes up approximately 0.5% of the bursal cell population, exhibits an eccentric nucleus with a chromatin pattern similar to that of a small lymphocyte and an elongated cytoplasm with one or more cell processes. The electron‐dense cytoplasmic granules of the immature secretory cell are localized around the cytocentrum, while in the mature secretory cell these granules are situated beneath the cell membrane of one process. The granular location endows a polarized appearance to the secretory cell. The surface of the membrane is covered with a finely spotted flocculated substance, which may originate from a granular discharge. The round, ovoid, or irregular‐shaped granules reveal a homogeneous or distinctive internal pattern. The cortico‐medullary border may be the germinal layer of the bursal medulla. The bursal secretory cell is a modified dendritic cell with possible endocrine functions that may be important in B‐cell in

ISSN:0003-276X    

DOI:10.1002/ar.1092190307

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

年代:1987

数据来源: WILEY

摘要:

AbstractNewly emerging neural crest (NC) cells will enter either the lateral pathway under the surface ectoderm or the vental pathway along the neural tube depending on the axial level (Pratt et al.:Dev. Biol.,44:298–305, 1975; Thiery et al.:Dev. Biol.,93:324–343, 1982; Newgreen et al.:Cell Tissue Res.,221:521–549, 1982; LeDouarin et al.: In:The Role of Extracellular Matrix in Development. Alan R. Liss, Inc., New York, pp. 373–398, 1984; Brauer et al.:Anat. Rec., 211:57–68, 1985). A number of studies have shown a correlation between the type of extracellular matrix (ECM) associated with adjacent tissues (e.g., ectoderm, neural tube, and mesoderm) and the initial pathway taken by NC cells. Our working hypothesis is that the direction of NC cell migration (ventral vs. lateral pathway) depends on the composition of the ECM associated with the surface ectoderm and its ability to support NC cell attachment. In this study, we tested this hypothesis by isolating endogenous ECM associated with the ectoderm of each region and examining the ability of each endogenous ECM to support cranial and trunk NC cell attachment in vitro. Results indicated that both cranial and trunk NC cells preferentially attached to cranial ectodermal ECM as compared to trunk ectodermal ECM. The differences in NC cell attachment were not due to a preferential adsorption of cranial ectodermal ECM onto the ECM‐conditioned plastic substrate over trunk ectodermal since approximately equal amounts of ECM bound to the plastic. These results supported the hypothesis and provide evidence that endogenous ectodermal ECM may be one factor potentially responsible for directing the NC cells along a ventral or a late

ISSN:0003-276X    

DOI:10.1002/ar.1092190308

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

年代:1987

数据来源: WILEY

摘要:

AbstractMercury is a major environmental pollutant and a proven teratogen in man and animals. Its teratogenicity and effects on fetal chromosomes were investigated in mice. Various dose levels of methylmercuric chloride (MMC) were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. On day 18 of gestation the animals were killed and the fetuses were removed. Fetal lung and liver tissues were processed for cytogenetic studies. Fetuses were also fixed in Bouin's solution for subsequent teratological examination by using Wilson's technique. Mercury levels were determined in maternal blood and randomly selected fetuses. One fetus from each litter was processed for skeletal staining with Alizarin Red S.A significant increase in embryonic deaths and resorptions was observed at all dose levels. The incidence of fetal anomalies was significantly increased following maternal treatment with 10, 15, or 20 mg/kg of MMC. Maternal weight between day 9 and day 18 of gestation decreased significantly. The LD50of MMC in pregnant mice was determined to be 20 mg/kg of body weight; the LD100was 30 mg/kg. A significant difference was observed between the mean fetal weights at the various dose levels.Levels of mercury were found to be significantly higher in treated animals and fetuses, and increased in a dose‐related manner. The levels of mercury were significantly higher in the fetuses than in the mothers at the same dosage, indicating a correlation between the levels of mercury in maternal mice and corresponding higher levels in their fetuses.Cytogenetic studies revealed significant clumping of chromosomes in metaphase at all dose levels and the frequency of clumping increased as dosage increased. The euploidy number (2n = 40) of chromosomes per cell did not vary between the treatment groups and control groups. The frequency of nucleolus‐organizing regions per cell did not change significantly between the treatment groups and the control. The frequency of sister chromatid exchanges increased significantly as the dosage increa

ISSN:0003-276X    

DOI:10.1002/ar.1092190309

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

年代:1987

数据来源: WILEY

摘要:

AbstractWe have analyzed the effects of colchicine on the cell shapes in chick neuroepithelium. Cell shapes were ascertained by the position of the nucleus in plastic serial sections. We tested three colchicine doses (5 × 10−5M, 5 × 10−6M, and 5 × 10−7M) by two experimental treatments (in ovo and in vitro). Colchicine treatment in vitro is always effective in depolymerizing microtubules of neuroepithelial cells and reduces the percentages of wedge‐shaped cells in the median area of neuroepithelium. The same effect can be observed when the embryos are treated with 5 × 10−5M or 5 × 10−6M colchicine in ovo. A concentration of colchicine of 5 × 10−7M in ovo cannot disrupt microtubules in stage 8 and stage 10 embryos, and the percentage of wedge‐shaped cells is the same as that of the untreated cells. In stage 6 embryos this colchicine dose effects the microtubules and the percentages of wedge‐shaped cells. These facts are interpreted in respect to variations in microtubular resistance to microtubular‐disrupting agents that are shown by the neuroepithelial cells from diffe

ISSN:0003-276X    

DOI:10.1002/ar.1092190310

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe egg development of the freshwater crayfish (Pacifastacus leniusculusDana) under laboratory conditions is studied in this work from spawning to hatching. The sequence of its development is presented here, and the chronology of the different embryonic phases is established at one specific temperature (15.5°± 1°

ISSN:0003-276X    

DOI:10.1002/ar.1092190311

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

年代:1987

数据来源: WILEY