摘要:

The spatial arrangement of blood vessels in the thymus of normal and hydrocortisone-injected mice was studied by light and electron microscopy. The thymus is supplied by one thymic artery which branches into arterioles as it enters the parenchyma.These, in turn, feed capillary networks in the cortex and in the medulla. Cortical networks at the periphery of the lobule form loops which return blood to postcapillary venules at the corticomedullary junction and in the medulla. There is no subcapsular venous drainage. The overall distribution of blood vessels in the involuted thymus is essentially the same as in the normal thymus but the pattern becomes irregular and the vessels are tortuous. The endothelium of the postcapillary venules is flat and surrounded by a wide perivascular space containing many lymphocytes. This space is delimited by basal laminae, on the one side by that of the abluminal surface of the venular endothelium, on the other side by that of a thin, sheet-like epithelial layer formed by cytoplasmic processes of reticular cells. The perivascular space is in continuity with the surrounding interstitial space via gaps in its epithelial sheet. It does not form continuous longitudinal channels along the venules, but is interrupted by epithelial trabeculae.There is no obvious difference in structure between the postcapillary venules and their perivascular spaces of normal and those of involuted thymuses. Lymphocytes are intercalated in the venular endothelium, particularly in involuted glands. They are present in the perivascular space and in gaps of the outer epithelial sheet.These findings suggest that the postcapillary venules and the perivascular spaces may function as pathways for the migration of thymic lymphocytes into or out of the blood circulation.

ISSN:1422-6405    

DOI:10.1159/000146715

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

This study was designed to elucidate the collagen fibril architecture in the murine anulus fibrosus and to reveal the collagen fibril dynamics induced by hormones which are known to influence protein synthesis, the anabolic steroid hormones. These aims were entered in an ultrastructural morphometric analysis. The diameter distributions, mean diameter, cross-sectional area and volume density of the collagen fibrils in the anulus fibrosus indicate no correlation with age, which is in contrast to the anatomy of the collagenous functional structures in tendon. After treatment with the anabolic steroid hormone, an activation of the collagen synthesis as well as an enhanced density and cross-sectional area were detected. Therefore, the data promise an effective use of anabolic steroid hormones in the therapy of such disorders of connective tissue, which could be treated with a stimulation of the synthesis and hypertrophy of collagen fibrils.

ISSN:1422-6405    

DOI:10.1159/000146716

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Apreembedding immunocytochemical technique enabled us to demonstrate normal human parafollicular (C) cells at the electron-microscopic level. The normal human C cells had numerous large secretory granules with a diameter of approximately 200 nm, well-developed rough endoplasmic reticulum and Golgi complex in their cytoplasm. Calcitonin immunoreactivity and calcitonin-gene-related peptide (CGRP) immunoreactivity were present only in the C cells whose secretory granules were heavily labeled. Both calcitonin and CGRP immunoreaction deposits were seen in the cytosol but not in the cisterna of endoplasmic reticulum, Golgi apparatus or mitochondrial matrix. The two peptides produced from a single calcitonin gene were stored in the secretory granules of the C cells.

ISSN:1422-6405    

DOI:10.1159/000146717

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The distribution of nerves and cholinesterase activity in the skin of the desert and albino rats has been studied using both histological and histochemical techniques. Inthe desert rat, the skin was richly innervated. Specific cholinesterase was concentrated in the nervous network of the dermis and around the hair follicles, in the nerve bundles of the dermis in perivascular nerves in fine intra-epithelial nerves and in sensory end organs in the junctional area between the dermis and epidermis. In the albino rat, specific cholinesterase was concentrated in the sebaceous glands. The positive cholinesterase activity that was seen in the desert rat in intra-epithelial nerves, and in dermal and hair follicle networks could not be demonstrated.

ISSN:1422-6405    

DOI:10.1159/000146718

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The deltoid and gluteus maximus of the desert rat and the albino rat were examined histochemically for the distribution of succinic dehydrogenase (SDH) and cholinesterase (ChE). SDH activity showed that the deltoid and gluteus maximus muscles of the two animals consisted of three types of muscle fibres, with a predominance of muscle fibres that have higher SDH activity in both the deltoid and gluteus maximus muscles of the desert rat than in the albino rat. The mean diameter of all muscle fibres in the deltoid and gluteus maximus muscles and their ratios to the average body weight were determined in both animals. The desert rat showed a statistically significant increase in those ratios compared with the corresponding ratios for the albino rat. ChE activity showed that the deltoid and gluteus maximus muscles are richly innervated by intensely positive ChE motor end-plates with a predominance of plaque-like terminals. The mean diameters of the end-plates and the ratios of these diameters to the diameter of the muscle fibres together with their ratios to the body weight were determined. A correlation between these values and the histological findings is proposed.

ISSN:1422-6405    

DOI:10.1159/000146719

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The identification of pituitary FSH and LH cells in states of pharmacological treatment influencing the pituitary FSH and LH production was performed by histological staining at the isoelectric points of these hormones in the cat. The intensity of the stained material in the hormone-producing cells was determined by a microphotometric technique. As a physiological control, the FSH and LH levels in blood were measured by a radioimmunoassay.

ISSN:1422-6405    

DOI:10.1159/000146720

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Rat gastrocnemius medialis (GM) and semimembranosus (SM) muscles have a very different morphology. GM is a very pennate muscle, combining relatively short muscle fibre length with sizable fibre angles and long muscle and aponeurosis lengths. SM is a more parallel-fibred muscle, combining a relatively long fibre length with a small fibre angle and short aponeurosis length. The mechanisms of fibre shortening as well as angle increase are operational in GM as well as SM. However, as a consequence of isometric contraction, changes of fibre length and angle are greater for GM than for SM at any relative muscle length. These differences are particularly notable at short muscle lengths: at 80% of optimum muscle length, fibre length changes of approximately 30% are coupled to fibre angle changes of 15° in GM, while for SM these changes are 4% and 0.6°, respectively. A considerable difference was found for normalized active slack muscle length (GM approximately 80 and SM approximately 45%).This is explained by differences of degree of pennation as well as factors related to differences found for estimated fibre length-force characteristics. Estimated normalized active fibre slack length was considerably smaller for SM than for GM (approximately 40 and 60% respectively). The most likely explanation of these findings are differences of distribution of optimum fibre lengths, possibly in combination with differences of myofilament lengths and/or fibre length distribution

ISSN:1422-6405    

DOI:10.1159/000146721

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Examination of the gross and microscopic anatomy of the kidney of the West Indian manatee, Trichechus mαnatus, revealed that: (1) the medulla is about 6 times thicker than the cortex; (2) juxtameduUary glomeruli have a mean diameter 1.3 times greater than that of cortical glomeruli; (3) juxtameduUary glomeruli have 1.7 times as much volume as cortical glomeruli; (4) there are about twice as many cortical glomeruli as juxtameduUary glomeruli per square millimeter of cortical tissue, and (5) the vasa recta are closely juxtaposed to the thin loops of Henle in the outer medulla. Many of these results suggest an enhanced urine-concentrating ability in this species

ISSN:1422-6405    

DOI:10.1159/000146722

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Arteries of mice were studied by a silver impregnation technique, by the Picrosirius-polarization method and by transmission electron microscopy. The histochemical results obtained coincided with the electron-microscopic observations in showing the presence of two distinct collagen populations, segregated into different compartments of each artery. The fibrous component of the tunica media was comprised of reticulin fibers, which displayed a distinct argyrophilia when studied by means of the silver impregnation technique, and showed up as thin, weakly birefringent, greenish fibers when examined with the aid of the Picrosirius-polarization method. In addition, the electron-microscopic studies disclosed the presence of thin collagen fibrils in the tunica media, contrasting with the thicker fibrils that could be localized ultrastructurally to the tunica adventitia where nonargyrophil, coarse collagen fibers had been characterized by the histochemical methods used. In this respect, collagen distribution in arteries of mice is very similar to the pattern that was consistently observed in the other species studied, which argues in favor of the existence of a uniform structural pattern of collagen distribution that is a general phenomenon in vertebrate arteries. Experimental results comparing the traditional method and the computer-aided measurement of collagen fibril diameters showed that the system provides results equivalent to those produced by manual execution. In addition, the advantage in speed of the computer-aided method should prove useful in complicated studies where nufherous structures are involved.

ISSN:1422-6405    

DOI:10.1159/000146723

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Although the vestibular and cochlear branches of the VΠIth cranial nerve originate embryologically from the same primordia, results of the present investigation confirm previous findings indicating that the vestibular branch may be more plastic with respect to recovery after surgical insult than the cochlear division. In this report we show ultrastructural details of changes undergone by the vestibular nerve after surgery. Dendrites peripheral to the vestibular nerve ganglion (VNG) were severed by surgically removing the vestibular end organs; the squirrel monkeys were then allowed to recuperate, and tested for their vestibulospinal and vestibulo-oculomotor functions behaviorally. However, behavior deficits resulting from the injury are reported separately. The vestibular nerves excised from the internal acoustic meatus and the temporal bones were examined histologically for changes of VNG and fibers from day 1 to 1,247 days after labyrinthectomy. Light- and electron-microscopic examinations indicated that some perikarya and some fibers of the VNG remained in the ganglionic matrix for up to 1,247 days, the longest period studied, after the operation. Fibers extended toward the remodeled inner ear space in the absence of appropriate sensory cell targets. The surviving neurons and fibers exhibited various degrees of wallerian-like degeneration at first, but many of them retained ultracellular organelles and integrity even after 1,247 days. Since vestibular perikarya are bipolar, the unse-vered fibers that project to the brainstem could retain functional synaptic connections, a possibility that is now under investigation. Schwann cells in the ganglionic matrix may also have contributed to vestibular neuron survival by providing the proper nourishment. Morphometric measurements determined that neurons remaining in the ganglion had significantly smaller cross-sectional areas than normal neurons. This shift in the cross-sectional area could have resulted from shrinkage of surviving neurons, or from preferential degeneration of the larger ganglion cells. Surgical removal of the sensory end organ structures was complete in all cases as verified histologically. The data presented here are complementary to those recently published in this journal about normal morphometric values of vestibular nerves in this species

ISSN:1422-6405    

DOI:10.1159/000146724

出版商:S. Karger AG    

年代:1989

数据来源: Karger