摘要:

In a study of the rat mandibular joint (MJ), Simon [Acta anat. 97: 351–360 (1977)] suggested that reduction in condylar cartilage thickness noted in animals subjected to removal or trimming of incisors resulted from the lessening of joint reaction forces produced during incision. In order to explore this question further, the microanatomy of the MJ in 47-day-old rats whose incisors had been trimmed every other day was compared to that in control animals and in a third group fed a soft diet as a control for reduced joint reaction forces. Both the incisor-clipped and soft-diet groups exhibited reduced size and density of bony trabeculae underlying the condylar cartilage and diminished staining for alcian blue. The thickness of the prechondroblastic layer of the condylar cartilage was significantly (p ≦ 0.01) reduced relative to controls in both experimental groups on the superior aspect of the cartilage, but was reduced in the more posterior parts of the cartilage only in the incisor-clipped group. While not denying that joint reaction forces may affect MJ response, the reduced prohferative response noted in the posterior region of the condylar cartilage in incisor-clipped animals is perhaps best explained by a decrease in the frequency and extent of protrusion of the lower jaw due to a lack of incisal preparation of food it

ISSN:1422-6405    

DOI:10.1159/000146153

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The teratogenic potential of L-asparaginase has been assayed in New cultures of explanted rat embryos. Embryos treated on day 9.5 with 1.5 IU L-asparaginase/ml of culture medium exhibited growth and development retardation together with malformations of the brain (exencephalia), eyes (anophthalmia or rudimentary sulcus opticus), face (characteristic appearance with anomalous frontolateral protrusions) and trunk (myeloschisis and turning absence). Neural ectoderm alterations were observed upon histological examination (anomalous fusions between the confronted neural folds as a consequence of the lack of turning and thickening) together with strong vascular dilatations at the cephalic level. Treatment on day 10.5 only caused minor differences in growth and protein content with respect to the control embryos. The possible teratogenic mechanism of this enzyme is discussed.

ISSN:1422-6405    

DOI:10.1159/000146154

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

A light microscopical study was conducted to ascertain the type of cells in the nucleus pulposus of theadult human intervertrebral disc. Three lumbar intervertebral discs were removed from each of 15 male and femaleadults at autopsy (ages ranged from 19 to 62 years). The tissue was fixed in formalin, decalcified in formic acid, dehydrated in a graded series of ethanol, embedded in paraffin, and serially sectioned at 7–10 µm. Tissue sectionswere affixed to albuminized glass slides and stained either by hematoxylin and eosin or hematoxylin and VanGieson’s stain. The cells of the bulk of the nucleus pulposus consisted of chondrocytes and a few fibroblasts;however, the subchondral matrix of the nucleus pulposos contained numerous stellate cells with (from 1 to 8)unusually long (up to 80 µm) primary cytoplasmic porcesses that often branch into secondary processes. The cellprocesses contained cytoplasmic varicosities at various intervals along their lengths; and their endings oftenexpanded into bulbous, vesicle-filled process terminals. The surrounding extracellular matrix usually containednumerous, vesicle-filled, eosinophil matrix bodies. Morphological similarities of cytoplasmic varicosities, processterminals, and matrix bodies, as well as the apparent budding of process terminals, suggest that these previouslyunidentified cells are secreting an unknown matrix component into the subchondral matrix of the nucleus pulposusof the adult hu

ISSN:1422-6405    

DOI:10.1159/000146155

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Intracytoplasmic crystalline bodies of various sizes are found in thyroid cells of 10-month-old mice and in younger animals under chronic lithium treatment. They are frequently surrounded by small microvesicles and dense bodies or enclosed in larger vesicles having a dense content. The crystalline skeleton is a network of protein fibers assembled in a characteristic axis with a periodicity of 8 nm. A deficiency of thyroid cell metabolism related to aging or lithium gluconate treatment would lead to an accumulation of substances of a crystalline pattern.

ISSN:1422-6405    

DOI:10.1159/000146156

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Adult mice were fed a choline-deficient ethionine enriched (CDE) diet for 24, 48 or 72 h. They were then fasted for 24 or 48 h prior to sacrifice. All tissues were studied by light and electron microscopy. Animals fed the CDE diet for 24 h exhibited cells with vacuolated cytoplasm, and the accumulation of lipid in these cells was clearly abnormal. Animals fed the CDE diet for 24 h and subsequently a regular diet for 48 h displayed normal hepatocytes, suggesting that the alterations at 24 h were reversible. Following 48 or 72 h of feeding the CDE diet, abundant lipid-laden cells were observed in the hepatic lobules, and at the electron microscope level these cells were undergoing frank degeneration. Evidence indicated that changes after 48 or 72 h were irreversible.

ISSN:1422-6405    

DOI:10.1159/000146157

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The authors analyzed the regenerative ability of cardiac muscle in the rat. Normal cardiac muscle was minced into mm3 fragments and homotransplanted into a triceps surae complex cavity of a nonsibling rat. Subsequent histological examination of the cardiac regenerate revealed the presence of myofibers. These myofibers typically exhibited centrally located nuclei, a characteristic of normal cardiac muscle. However, the absence of intercalated discs and autonomous contractility prevented indentification of these fibers as cardiac.

ISSN:1422-6405    

DOI:10.1159/000146158

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Chick embryos were staged according to the method of Hamburger and Hamilton [1951] and fixed. Cross sections through the cephalic fourth of the mesonephric ridges were examined by scanning electron microscopy. The steps in glomerular differentiation could be observed with ease. The first foot processes to appear in podocytes arose directly from the basal surface of the cell body. In a second step, lateral branches appeared and gave off secondary or even tertiary branches that interdigitated with those from neighbouring podocytes, following a pattern that was very similar to the one previously described by other authors in metanephric nephrons. Endothe-lial pores appeared in the glomerular capillaries at very early stages of the glomerular differentiation. The differentiation of the epithelium of proximal tubules was characterized by the growth of apical microvilli and of finger-like evaginations from the lateral membranes. At stages 20 and 21, the most differentiated glomeruli had only basal foot processes; only after stage 25 did the first generation nephrons reach full maturity. Because during this period the mesonephros is known to produce urine, our results indicate that nephrons start to function before they have completed their differentiation.

ISSN:1422-6405    

DOI:10.1159/000146159

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Growth in volume of the anulus fibrosus (AF) and nucleus pulposus (NP) was quantified using serial histological sections of human and kitten fetuses. Fetal intervertebral discs were studied that had clearly outlined AF and NP. Regression equations were calculated and graphs plotted by microcomputer. An increase in surface areas of these intervertebral structures was also recorded; however, volume was a better indicator of relative growth than was surface area. The AF volume of the fetal human increased more in proportion to the intervertebral disc than it did for the fetal kittens. There was significantly slower growth of the human NP compared to the kitten NP when related to the total intervertebral disc. The analysis for each species was done separately. Comparisons of the growth relationships of humans and kittens for the AF and NP were related to crown-rump length as the independent variable, and were different at the p≤O.01 level of significance. The thoracic intervertebral discs were emphasized due to species-specific differential growth of the AF. The intercapital ligament (IC) was separated from mesenchyme over the dorsal surface of the kitten AF, and this affected the relationships of AF and NP volumes when compared to humans. Use of human histological sections is essential in the study of differential growth of the human vertebral column because fetal kittens have an IC that affects relative growth of both AF and N

ISSN:1422-6405    

DOI:10.1159/000146160

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The ultrastructural changes in the left ventricles of rabbits with alloxan (100 mg/kg i.v.)-induced diabetes were examined. Injection of alloxan resulted in a diabetic state characterized by increased hemoglobin glycosylation, blood and urine glucose and a significant depression of serum insulin levels. Electron microscopic examination of 10-week diabetic hearts revealed a spectrum of abnormalities ranging from mild to severe. Cardiac muscle cells in diabetic hearts showed some myofibrillar damage and varying degrees of contraction. The most prominent findings, however, were alterations in the mitochondria. Swollen and fragmented mitochondria containing amorphous dense bodies were evident upon electron microscopic examination. The cristae in the mitochondria appeared distorted and in some cases were completely lysed. A marked increase in lipid droplets and glycogen granules was also apparent. In addition, the sarcoplasmic reticulum was dilated and contained varying degrees of electron-dense material. These ultrastructural alterations suggest that the cardiomyopathy observed in alloxan-induced diabetic rabbits could be due to alterations in the vasculature or may be secondary to a number of metabolic alterations previously reported in this model.

ISSN:1422-6405    

DOI:10.1159/000146161

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Although sheep erythrocytes (SRBCs) are extensively used as an antigen in immunological studies, their histological distribution in lymphoid tissues has received little attention. The objective of this study was to determine the histological distribution of injected SRBCs in rat spleen. SRBCs were labelled with fluorescein isothiocyanate (FITC) to facilitate their identification in spleen sections with fluorescence microscopy. Rats received intravenous injections of FITC-labelled SRBCs and were sacrificed at various periods after injection. At 15 min, SRBCs were distributed throughout the marginal zone and red pulp. After 4 h, intact SRBCs were located mainly in the red pulp, while the marginal zone contained fluorescent flocculent material. At later periods this material was present in the periarterial lymphatic sheath (PALS) and in the light and dark zones of the germinal centers. By 12 h, the most intensely labelled areas in the white pulp were the crescent-shaped light zones. In 12 and 24 h, the PALS contained numerous foci of labelled granules. Some of the dark zones also contained label. After 48 h, the only areas containing label were the light zones of the germinal centers.

ISSN:1422-6405    

DOI:10.1159/000146162

出版商:S. Karger AG    

年代:1986

数据来源: Karger