bluuebunny/crossref_metadata_2025 huggingface dataset:
The interface between bone and tendon at an insertion site: a study of the quadriceps tendon insertion
Authors: CLARK JOHN , STECHSCHULTE DANIEL J.
Published: March 2003

Traumatic avulsions of ligament or tendon insertions rarely occur at the actual interface with bone, which suggests that this attachment is strong or otherwise protected from injury by the structure of the insertion complex. In this study we describe the terminal extent of quadriceps tendon fibres where they insert into the patellae of adult rabbits, humans, dogs and sheep. Specimens were examined by scanning electron microscopy (SEM) and light microscopy (LM). To facilitate tracing of tendon fibres the specimens were decalcified for SEM, and polarised light microscopy (PLM) was used in the LM segment of the study. By SEM it was possible to identify mature bone by the presence of osteocytes and a lamellar organisation. PLM and SEM showed that, unlike tendon fibres elsewhere, those in the calcified fibrocartilage were not crimped. No specific cement line was identified by SEM. Tendon fibres interdigitated among separate bone lamellar systems, (osteons or marrow spaces), but did not merge with the collagen systems of individual lamellae. The interdigitation was more extensive and the margin between tendon and bone was less distinct in the anterior third of the insertion. The segment of calcified tendon which interdigitated with bone stained less intensely blue and was less cellular than the more proximal calcified fibrocartilage zone adjacent to the tidemark. Lamellar collagen fibres of the bony trabeculae in the anterior patella were unusually parallel and longitudinal in orientation, making distinction of interposed tendon fibres difficult on LM and PLM sections. LM, SEM and transmission electron microscopy of rabbit patellae at birth revealed that anterior quadriceps tendon fibres extended over the patella in a fibrous cellular layer. By 2 wk of age, this layer had acquired chondroid features (i.e. cell lacunae and metachromasia) and contained vessels extending from patellar marrow. At 6 wk of age, part of this fibrocartilaginous layer was replaced by mature bone and osteoid. In the young adult animal, the quadriceps tension interdigitates extensively with the patellar bone. This segment of the insertion is perhaps the remnant of calcified fibrocartilage which has been remodelled by bone formation.
Morphological study by an ‘in vivo cryotechnique’ of the shape of erythrocytes circulating in large blood vessels
Authors: XUE MEI , KATO YASUKO , TERADA NOBUO , FUJII YASUHISA , BABA TAKESHI , OHNO SHINICHI
Published: March 2003

Changes in the shape of erythrocytes circulating in large blood vessels of mice were examined by our ‘in vivo cryotechnique’. The abdominal aorta and inferior vena cava (IVC) were cut vertically with a precooled knife and simultaneously an isopentane–propane mixture (−193°C) was poured over them for freezing. They were freeze‐substituted in acetone containing 2% osmium tetroxide. Some specimens were embedded in Quetol‐812, and thick or ultrathin sections were examined by light or transmission electron microscopy. Serial ultrathin sections were used to reconstruct 3‐dimensional images of native erythrocytes. Others were transferred into t‐butyl alcohol and freeze‐dried for scanning electron microscopy. The tissue surfaces were sufficiently frozen to prevent large ice crystal formation, and erythrocyte shapes were also preserved. The shapes of circulating erythrocytes appeared to be varied in the abdominal aorta but typical biconcave discoid shapes were rarely observed. Conversely, erythrocytes were approximately biconcave discoid in shape in the IVC. Our in vivo cryotechnique was useful for clarifying the in vivo morphology of erythrocytes circulating in large blood vessels.
Facial growth in Cercocebus torquatus: an application of three‐dimensional geometric morphometric techniques to the study of morphological variation
Authors: O'HIGGINS PAUL , JONES NICHOLAS
Published: March 2003

This paper presents a study of 3‐dimensional growth in the facial skeleton of the mangabey, Cercocebus torquatus. The pattern of facial cortical remodelling in this species is already well mapped from an earlier study. In this paper we consider the extent to which these remodelling maps relate to ontogenetic changes in size and shape of the face. This study is based on 31 facial landmarks taken from 49 adult and subadult faces. Our analysis draws on some of the tools of geometric morphometrics and we take this opportunity to describe our implementation of these tools for 3D data. The geometric analysis permits the known remodelling maps to be interpreted in the context of the general pattern of facial growth in this species. We are also able to examine sexual dimorphism in the face of this species and consider the extent to which males and females share similar ontogenetic allometries. Our findings indicate that the general pattern of size‐related shape variation during facial growth is more or less identical for males and females up to eruption of the third permanent maxillary molar (M3). After this, ontogenetic allometries appear to diverge. The finding of a common growth allometry that is well approximated for younger specimens by a simple linear model is consistent with the earlier findings of a consistent pattern of facial remodelling up to M3 eruption. We consider the implications of these findings in terms of the potential for these approaches in the study of comparative growth in related species.
Expression of tissue type and urokinase type plasminogen activators as well as plasminogen activator inhibitor type‐1 and type‐2 in human and rhesus monkey placenta
Authors: HU ZHAO‐YUAN , LIU YI‐XUN , LIU KUI , BYRNE SIMON , NY TOR , FENG QIANG , OCKLEFORD COLIN D.
Published: March 2003

The distribution of mRNAs and antigens of tissue type (t) and urokinase type (u) plasminogen activators (PA) plus their corresponding inhibitors, type‐1 (PAI‐1) and type‐2 (PAI‐2) were studied in human and rhesus monkey placentae by in situ hybridisation and immunocytochemistry. Specific monkey cRNA and antibodies against human tPA, uPA, PAI‐1 and PAI‐2 were used as probes. The following results were obtained. (1) All the molecules tPA, uPA, PAI‐1 and PAI‐2 and their mRNAs were identified in the majority of the extravillous cytotrophoblast cells of the decidual layer between Rohr's and Nitabuch's striae and in cytotrophoblast cells of the chorionic plate, basal plate, intercotyledonary septae and cytotrophoblast cells of the chorionic villous tree. (2) Expression of uPA and PAI‐2 was noted in villous trophoblast whereas tPA and PAI‐1 were mainly concentrated where detachment from maternal tissue occurs. (3) No expression of tPA, uPA, PAI‐1 and PAI‐2 was observed in the basal plate endometrial stromal cells, chorionic plate connective tissue cells, septal endometrial stromal cells or villous core mesenchyme. (4) The distribution of probes observed following in situ hybridisation is generally consistent with the immunofluorescence pattern of the corresponding antigens and no significant interspecies differences were noted. It is possible that both decidual and extravillous trophoblast cells of placentae of human and rhesus monkey are capable of producing tPA, uPA, PAI‐1 and PAI‐2 to differing extents. Coordinated expression of these genes in the tissue may play an essential role in the maintenance of normal placentation and parturition. The differences in distribution we observed are consistent with the suggestion that coordinated expression of tPA and its inhibitor PAI‐1 may play a key role in fibrinolytic activity in the early stages of placentation and separation of placenta from maternal tissue at term. On the other hand, uPA with its inhibitor PAI‐2 appears mainly to play a role in degradation of trophoblast cell‐associated extracellular matrix, and thus may be of greatest importance during early stages of placentation.
Anatomical differences in the psoas muscles in young black and white men
Authors: HANSON PATRICK , MAGNUSSON S. PETER , SORENSEN HENRIK , SIMONSEN ERIK B.
Published: March 2003

The anatomy of the psoas major muscle (PMA) in young black and white men was studied during routine autopsies. The forensic autopsies included 44 fresh male cadavers (21 black, 23 white) with an age span of 14 to 25 y. The range for weight was 66–76 kg and for height 169–182 cm. The PMA was initially measured in its entire length before measuring the diameter and circumference at each segmental level (L1–S1). At each segmental level, the calculated anatomical cross‐sectional area (ACSA) was more than 3 times greater in the black group compared with the white (P<0.001). The psoas minor muscle (PMI) was absent in 91% of the black subjects, but only in 13% of the white subjects. These data show that the PMA is markedly larger in black than white subjects. The marked race specific difference in the size of the PMA may have implications for hip flexor strength, spine function and race specific incidence in low back pathology, and warrants further investigation.
Regional differences in fibre type composition in the human temporalis muscle
Authors: KORFAGE J. A. M. , VAN EIJDEN T. M. G. J.
Published: March 2003

Anatomical and electromyographic studies point to regional differences in function in the human temporalis muscle. During chewing and biting the anterior portions of the muscle are in general more intensively activated and they are capable of producing larger forces than the posterior portions. It was hypothetised that this heterogeneity in function is reflected in the fibre type composition of the muscle. The composition and surface area of different fibre types in various anteroposterior portions of the temporalis muscle were investigated in 7 cadavers employing immunohistochemistry with a panel of monoclonal antibodies against different isoforms of myosin heavy chain. Pure slow muscle fibres, type I, differed strongly in number across the muscle. In the most posterior portion of the muscle there were 24% type I fibres, in the intermediate portion 57%, and in the most anterior portion 46%. The mean fibre cross‐sectional area (m‐fcsa) of type I fibres was 1849 μm2, which did not differ significantly across the muscle. The proportion of pure fast muscle fibres, type IIA and IIX, remained more or less constant throughout the muscle at 13% and 11% respectively; their m‐fcsa was 1309 μm2 and 1206 μm2, respectively, which did not differ significantly throughout the muscle. Pure type IIB fibres were not found. The relative proportion of hybrid fibres was 31% and did not differ significantly among the muscle portions. Fibre types I+IIA and cardiac α+I+IIA were the most abundant hybrid fibre types. In addition, 5% of the type I fibres had an additional myosin isoform which has only recently been described by means of electrophoresis and was named Ia. In the present study they were denoted as hybrid type I+Ia muscle fibres. It is concluded that intramuscular differences in type I fibre distribution are in accordance with regional differences in muscle function.
Immunohistochemical evidence suggests intrinsic regulatory activity of human eccrine sweat glands
Authors: ZANCANARO CARLO , MERIGO FLAVIA , CRESCIMANNO CATERINA , ORLANDINI SIMONETTA , OSCULATI ANTONIO
Published: March 2003

Immunohistochemistry of normal eccrine sweat glands was performed on paraffin sections of human skin. Immunoreactivity (ir) for neuron specific enolase, S100 protein (S100), regulatory peptides, nitric oxide synthase type I (NOS‐I) and choline‐acetyltransferase (ChAT) was found in small nerve bundles close to sweat glands. In the glands, secretory cells were labelled with anticytokeratin antibody. Using antibodies to S100, calcitonin gene‐related peptide (CGRP) and substance P (SP) a specific distribution pattern was found in secretory cells. Granulated (dark) and parietal (clear) cells were immunopositive for CGRP, and S100 and SP, respectively. Immunoreactivity was diffuse in the cytoplasm for CGRP and S100, and peripheral for SP. Myoepithelial cells were not labelled. Electron microscopy revealed electron dense granules, probably containing peptide, in granulated cells. Using antibodies to NOS‐I and ChAT, ir was exclusively found in myoepithelial cells. Immunoreactivity for the atrial natriuretic peptide was absent in sweat glands. These results provide evidence for the presence of both regulatory peptides involved in vasodilation and key enzymes for the synthesis of nitric oxide and acetylcholine in the secretory coil of human sweat glands. It is suggested that human sweat glands are capable of some intrinsic regulation in addition to that carried out by their nerve supply.
Microvascular features and ossification process in the femoral head of growing rats
Authors: MORINI SERGIO , PANNARALE LUIGI , FRANCHITTO ANTONIO , DONATI SAARA , GAUDIO EUGENIO
Published: March 2003

In the epiphysis of long bones, different patterns of development of ossification processes have been described in different species. The development of the vascularisation of the femoral head has not yet been fully clarified, although its role in the ossification process is obvious. Our aim was to investigate ossification and vascular proliferation and their relationship, in growing rat femoral heads. Male Wistar rats aged ∼ 1, 5 and 8 wk and 4, 8 and 12 mo were used. Light microscopy frontal sections and vascular corrosion casts observed by scanning electron microscopy were employed. In the rat proximal femoral epiphysis, ossification develops from the medullary circulation of the diaphysis, quickly extending to the neck and the base of the head. Hypertrophic chondrocytes occupy the epiphyseal cartilage, and a physeal plate with regular cell columns is present. Starting from about the end of the third month one or more points of fibrovascular outgrowth, above the physeal line, can be observed in each sample. They are often placed centrally or, sometimes, peripherally. The fibrovascular outgrowths penetrate deeply into the cartilage and extend laterally. At age 8 mo, large fibro‐osseous peduncles connect the epiphysis to the diaphyseal tissue. At 12 mo, the entire epiphysis appears calcified with an almost total absence of residual cartilage islands. This situation differs in man and in other mammals due both to differing thickness of the cartilage and to the presence of more extensive sources of blood vessels other than the diaphyseal microcirculation, as supplied by the teres ligament and Hunter's circle. In young rats, subchondral vessels and the synovial fluid could play a role in feeding the ossifying cartilage. Later, a loss of resistance of the physis due to marked degeneration of the cell columns, and extensive chondrocyte hypertrophy permit fibrovascular penetration starting from diaphyseal vessels rather than neighbouring vascular territories, such as those of the periosteum and capsule.
The vomeronasal organ in the human embryo, studied by means of three‐dimensional computer reconstruction
Authors: SHERWOOD REBECCA J. , MCLACHLAN JOHN C. , AITON JAMES F. , SCARBOROUGH JULIE
Published: March 2003

The human vomeronasal organ is of interest because of its potential role in sex pheromone detection. Due to the scarcity of early human material, studies of its development have concentrated on fetal rather than embryonic stages. The availability of embryonic specimens in the Walmsley Collection has enabled us to study the development of the vomeronasal organ (VNO) in human embryos between Carnegie Stages 17 and 23. Embryos at Carnegie Stage 17 or below showed no evidence of a VNO. One embryo with characteristics intermediate between Carnegie stages 17 and 18 was the earliest to show evidence of a VNO, in the form of a shallow indentation. All embryos at Carnegie Stages 18 or later had VNOs. Three‐dimensional computer reconstructions were made of the VNO in each specimen where this was possible. This in part depended on the plane of section. The total volume and lumen volume were measured from these reconstructions and the volume of the vomeronasal epithelium was calculated by subtraction. A generally consistent increase in total volume and epithelial volume was observed with increasing developmental stage. The lumen contributed rather little to the total volume at these stages.
Relationship of decrease in fecundity with advancing age to structural changes in mouse endometrium
Authors: SHIMIZU KIYOSHI , YAMADA JINZO
Published: March 2003

The aim of this study was to determine whether a relationship exists between decrease in fecundity and structural changes in the antimesometrial endometrium of the mouse. Fecundity was calculated as the number of animals showing a placental sign/number of copulated animals ×100 (%). Structural changes in the endometrium were examined by electron microscopy. A negative correlation between age and fecundity was found. Fecundity was 50% at 7 mo of age. At this age, amorphous material appeared in the region between the basement membrane deep to the luminal epithelium and the subepithelial cells. This material was sometimes attached to the basement membrane. It increased in amount with advancing age, as fecundity decreased. The structure of the uterine luminal epithelial cells did not alter with age. The results indicated that decrease in fecundity with advancing age is correlated with the appearance of amorphous material beneath the basal lamina of the endometrial epithelium. It is suggested that this could impair communication between the luminal epithelium and the endometrial stroma, which plays an important role in implantation.
Parvalbumin in cortical epithelial cells of the pigeon thymus
Authors: ATOJI YASURO , YAMAMOTO YOSHIO , SUZUKI YOSHITAKA
Published: March 2003

We examined the distribution of parvalbumin in the pigeon thymus by light and electron microscopic immunohistochemistry. Tissues were also examined by conventional electron microscopy to determine the ultrastructure of immunoreactive cells. Parvalbumin immunoreaction was located in epithelial cells of the cortex, which formed dense mesh‐like structures. Parvalbumin‐positive epithelial cells were classified into 2 types. The first comprised elongated cells. In these, the nucleus was spindle‐shaped, oval, or triangular, with a slightly irregular contour and contained rich heterochromatin peripherally. The cytoplasm was pale and processes extended laterally or ramified among the surrounding thymocytes. This type of cell formed the majority of immunoreactive cells. The other cell type consisted of polygonal epithelial cells. The nucleus was oval with deep indentations. Euchromatin occupied a large part of the nucleus. The cytoplasm contained numerous cell organelles compared with the elongated type, in particular, electron‐dense vacuoles of various sizes and often bundles of tonofilaments. Both types of epithelial cell were interconnected by desmosomes. No secretory granules were found in the cytoplasm of elongated or polygonal cells. These results indicate the presence of heterogeneous group of parvalbumin‐immunoreactive epithelial cells and suggest the likelihood of different functional roles for parvalbumin in the pigeon thymus.
Imaging basal ganglia function
Authors: BROOKS DAVID J.
Published: March 2003

In this review, the value of functional imaging for providing insight into the role of the basal ganglia in motor control is reviewed. Brain activation findings in normal subjects and Parkinson's disease patients are examined and evidence supporting the existence for functionally independent distributed basal ganglia‐frontal loops is presented. It is argued that the basal ganglia probably act to focus and filter cortical output, optimising the running of motor programs.
The growth promoting effects of bFGF, PD‐ECGF and VEGF on cultured postimplantation rat embryos deprived of serum fractions
Authors: ULGER HARUN , KARABULUT AHMET K. , PRATTEN MARGARET K.
Published: March 2003

Serum components in which embryos are cultured in vitro are very important for normal embryonic development. In this study, rat serum was fractionated using Macrosep filters to study the effect of a single growth factor. The fractionated serum, both that containing only material greater than 30 kDa molecular weight (> 30 kDa) and that from which material between 30 kDa and 50 kDa had been removed (< 30 kDa + > 50 kDa), caused significant embryonic growth retardation. Addition of different concentrations of basic fibroblast growth factor (bFGF, 18 kDa), vascular endothelial growth factor (VEGF, 45 kDa) and platelet‐derived endothelial growth factor (PD‐ECGF, 45 kDa), to fractionated serum (bFGF to > 30 kDa serum and VEGF or PD‐ECGF to < 30 kDa + > 50 kDa serum) partially restored embryonic growth and development according to a morphological scoring system and protein assay. This restoration was clear by all criteria, as well as in yolk sac vascularisation and heart development. The growth promoting effects of all 3 factors were significant but did not reach the level seen in embryos grown in whole rat serum. The effect of these growth factors was also investigated on anembryonic yolk sac development using a concentration for which maximum whole embryonic growth was seen (128 ng/ml bFGF, 1.6 ng/ml VEGF and 4 ng/ml PD‐ECGF), and significant anembryonic yolk sac development was found. These findings suggest that the angiogenic factors may have a growth promoting effect on total embryonic development and vascularisation.
The thymus in the mouse changes its activity during pregnancy: a study of the microenvironment
Authors: KENDALL MARION D. , CLARKE ANN G.
Published: March 2003

The mouse thymus changes dramatically during pregnancy. It shrinks in size, and the cortex is extensively reduced from midpregnancy onwards. Despite this, there is surprisingly little evidence for any increase in apoptosis, and considerable evidence that mitosis of thymocytes continues throughout pregnancy. In spite of overall involution the thymic medulla actually expands in midpregnancy due to a combination of mitosis of epithelial cells and an accumulation of lymphocytes. The extent and nature of these changes are examined in this study at the ultrastructural level. The epithelial cells of the subcapsular cortex (type 1 cells) become wrinkled and exhibit powers of phagocytosis, whilst the other cortical epithelial cells are relatively unchanged, although the formation of epithelial/thymocyte rosettes and thymic nurse cells is more clearly seen in midpregnancy than usual. Other changes associated with pregnancy involve the medullary epithelial cells that undergo an increased level of mitosis. Their greater numbers surround accumulations of lymphocytes to form the characteristic medullary epithelial rings. Cell movement through blood vessel walls was clearly observed in midpregnancy, but not at other times. Interdigitating cells in the medulla become more conspicuous as pregnancy proceeds and the cells become phagocytic. The endoplasmic reticulum in plasma cells becomes expanded, indicating increased secretory activity. These results highlight the active nature of the thymus in pregnancy in spite of its involution. This picture contradicts the conventional notion that an involuted thymus is inactive.
Ultrastructural localisation of NADPH‐d/nNOS expression in the superior cervical ganglion of the hamster
Authors: TSENG CHI‐YU , LUE JUNE‐HORNG , CHANG HUNG‐MING , WEN CHEN‐YUAN , SHIEH JENG‐YUNG
Published: March 2003

This study examined NADPH‐d and nNOS expression in the SCG of hamsters. By light microscopy, numerous NADPH‐d/NOS positive processes were widely distributed in the ganglion. Ultrastructurally, the NADPH‐d reaction product was associated with the membranous organelles of neuronal soma, dendrites, myelinated fibres, small granular cells, and axon profiles bearing agranular vesicles. The NOS immunoreaction product, on the other hand, was localised in the cytoplasm of principal neurons and dendrites. Some of the NADPH‐d/NOS labelled processes formed junctional contacts including synapses or zonulae adherentia. Compared with the neurons, the nonneuronal cells in the ganglion, namely, macrophages, satellite cells and endothelial cells were labelled by NADPH‐d but devoid of nNOS immunoreaction product. The results suggest that the NADPH‐d/NOS positive fibres in the SCG originate not only from the projecting fibres of the lateral horns of thoracic spinal cord, but also from the principal neurons and small granular cells; some may represent visceral afferent fibres. Electron microscopic morphometry has shown that about 67% of the principal neurons contain NADPH‐d reaction product, and that the majority were small to medium sized neurons based on cross‐sectional areas in image analysis. On the basis of the present morphological study, it is concluded NO is produced by some local neurons and possibly some nonneuronal cells in the SCG as well as some fibres of extrinsic origin. In this connection, NO may serve either as a neurotransmitter or neuromodulator.
Anatomical variations in the pattern of the right hepatic veins: possibilities for type classification
Authors: DE CECCHIS LUCIO , HRIBERNIK MARIJA , RAVNIK DEAN , GADŽIJEV ELDAR M.
Published: March 2003

A morphological study of the right hepatic veins (RHVv) was conducted based on the shape and the confluence pattern of the superior right hepatic vein (SRHV) and the presence of accessory right hepatic veins. The study was performed in 110 undamaged, randomly selected, cadaveric human livers prepared using the corrosion cast methodology. The principles for classifying the RHVv into types were as follows: the length of the vein trunk, the confluence of 2 or 3 main tributaries that form a trunk, and the accessory right hepatic veins that modify the venous drainage of the right side of the liver. Four types of SRHV were identified. Type 1 (20%), type 2 (40%) and type 3 (25%) were the most common, while type 4 (15%) was linked to the accessory right hepatic veins in cases where they drain a surgically important part of the liver. Accessory right hepatic veins were found in a total of 31 casts (28%). The hepatocaval confluence was studied and the tributary‐free part of the SRHV trunk before it entered the inferior vena cava was measured. The tributary‐free part of the SRHV was longer than 1 cm in 77% of the casts. Anastomoses between the terminal tributaries of the veins involved in the drainage of the right side of the liver were also investigated.
VEGF enhances intraneural angiogenesis and improves nerve regeneration after axotomy
Authors: HOBSON MARK I. , GREEN COLIN J. , TERENGHI GIORGIO
Published: March 2003

Whilst there is an increased understanding of the cell biology of nerve regeneration, it remains unclear whether there is a direct interrelationship between vascularisation and efficacy of nerve regeneration within a nerve conduit. To establish this is important as in clinical surgery peripheral nerve conduit grafting has been widely investigated as a possible alternative to the use of nerve autografts. The aim of this study was to assess whether vascular endothelial growth factor (VEGF), a highly specific endothelial cell mitogen, can enhance vascularisation and, indirectly, axonal regeneration within a silicone nerve regeneration chamber. Chambers containing VEGF (500–700 ng/ml) in a laminin‐based gel (Matrigel) were inserted into 1 cm rat sciatic nerve defects and nerve regeneration examined in relation to angiogenesis between 5 and 180 d. Longitudinal sections were stained with antibodies against endothelial cells (RECA‐1), axons (neurofilament) and Schwann cells (S‐100) to follow the progression of vascular and neural elements. Computerised image analysis demonstrated that the addition of VEGF significantly increased blood vessel penetration within the chamber from d 5, and by d 10 this correlated with an increase of axonal regeneration and Schwann cell migration. The pattern of increased nerve regeneration due to VEGF administration was maintained up to 180 d, when myelinated axon counts were increased by 78% compared with plain Matrigel control. Furthermore the dose‐response of blood vessel regeneration to VEGF was clearly reflected in the increase of axonal regrowth and Schwann cell proliferation, indicating the close relationship between regenerating nerves and blood vessels within the chamber. Target organ reinnervation was enhanced by VEGF at 180 d as measured through the recovery of gastrocnemius muscle weights and footpad axonal terminal density, the latter showing a significant increase over controls (P < 0.05). The results demonstrate an overall relationship between increased vascularisation and enhanced nerve regeneration within an acellular conduit, and highlight the interdependence of the 2 processes.
The cells of the rabbit meniscus: their arrangement, interrelationship, morphological variations and cytoarchitecture
Authors: HELLIO LE GRAVERAND MARIE‐PIERRE , OU YONGCHUNG , SCHIELD‐YEE TERESA , BARCLAY LEONA , HART DAVID , NATSUME TAKASHI , RATTNER J. B.
Published: March 2003

Four major morphologically distinct classes of cells were identified within the adult rabbit meniscus using antibodies to cytoskeletal proteins. Two classes of cell were present in the fibrocartilage region of the meniscus. These meniscal cells exhibited long cellular processes that extended from the cell body. A third cell type found in the inner hyaline‐like region of the meniscus had a rounded form and lacked projections. A fourth cell type with a fusiform shape and no cytoplasmic projections was found along the superficial regions of the meniscus. Using a monoclonal antibody to connexin 43, numerous gap junctions were observed in the fibrocartilage region, whereas none were seen in cells either from the hyaline‐like or the superficial zones of the meniscus. The majority of the cells within the meniscus exhibited other specific features such as primary cilia and 2 centrosomes. The placement of the meniscal cell subtypes as well as their morphology and architecture support the supposition that their specific characteristics underlie the ability of the meniscus to respond to different types of environmental mechanical loads.
Dermal fibroblasts participate in the formation of new muscle fibres when implanted into regenerating normal mouse muscle
Authors: PYE DEBORAH , WATT DIANA J.
Published: March 2003

Both in vitro and in vivo studies have described the conversion of fibroblasts to myogenesis when in the presence of dysfunctional myogenic cells. Myogenic conversion of fibroblasts subjected to a normal, as opposed to a diseased muscle environment has only been reported in vitro. The primary aim of this work was to determine if fibroblasts can convert to a myogenic lineage and contribute to new fibre formation when implanted into the regenerating muscle of a normal mouse. Dermal fibroblasts were prepared from neonatal mouse skin and labelled prior to implantation with the fluorescent nuclear marker 4′,6‐diamidino‐2‐phenylindole (DAPI). Cells were implanted into muscles of host mice that had been subjected to either cold/crush or minced muscle injury. Some host muscles were x‐irradiated to deplete the muscle of endogenous muscle precursor cells. Muscles were removed at 3 wk postimplantation and analysed both histologically and for the presence of DAPI labelled nuclei. Fibres containing DAPI labelled central nuclei indicated that the implanted cells had participated in the regenerative process. Mouse dermal fibroblasts therefore do contribute to muscle fibre formation in regenerating normal mouse muscle but the extent of their contribution is dependent on the nature of the trauma induced in the host muscle. The study also showed that regeneration was more successful in muscles which had not been irradiated, which is contrary to the previous studies where dermal fibroblasts were introduced into myopathic mouse muscle.
Distribution of tracheal and laryngeal mucous glands in some rodents and the rabbit
Authors: WIDDICOMBE J. H. , CHEN L. L‐K. , SPORER H. , CHOI H. K. , PECSON I. S. , BASTACKY S. J.
Published: March 2003

We used scanning electron microscopy to count the number of mucous gland openings in the tracheae and lower portion of the larynges of the rat, guinea pig, hamster, mouse and rabbit. Cells of the airway surface epithelium were removed by protease digestion better to visualise the gland openings. The distribution of glands was further studied by conventional histology and by PAS/Alcian blue staining of whole mounts. In all rodent species, gland openings in the larynx occurred with a frequency of 1–2 per mm2. Mice had no gland openings in their tracheae, and hamsters, only a handful. Rat tracheae contained 126±42 gland openings (±S.D.; n = 6) at a frequency of ∼ 0.6 per mm2 at the top of the trachea and ∼ 0.15 per mm2 at the bottom. Guinea pig tracheae contained 153±90 gland openings (±S.D.; n = 5), with 54% being in the top 40% of the trachea. In both rat and guinea pig, tracheal glands were found in the ventral aspect between the cartilaginous rings, and were absent from the dorsal membranous portion. Gland openings in most species were simple circles of ∼ 50 μm diameter. However, glands in the rat trachea generally opened obliquely into shallow (∼ 20 μm deep) oval troughs (∼ 150×75 μm), which had their long axes oriented from head to tail. In the rabbit, there was no evidence of tracheal or laryngeal glands histologically. However, the tracheal and laryngeal surfaces contained numerous pits (∼ 30 μm diameter) distributed evenly over and between cartilages at a frequency of ∼ 4 per mm2. These may correspond to the ‘nests’ of goblet cells described by others.
The orientation of the articular facets of the zygapophyseal joints at the cervical and upper thoracic region
Authors: PAL G. P. , ROUTAL R. V. , SAGGU S. K.
Published: March 2003

Knowledge of the orientation of facet joints in the cervical and upper thoracic region is important for understanding the biomechanical properties and clinical conditions relevant to the neck. The study was undertaken on dry macerated bones from 30 adult male human vertebral columns. The orientation of the superior articular facets in relation to their inclination with the sagittal and transverse planes was examined between C3 and T3 vertebrae in each column. The linear dimensions of the superior articular facets and the width/height ratio were also calculated. The results show that all vertebrae at C3 level and 73% at C4 level displayed posteromedially facing superior articular facets. Similarly at T1 level (C7/T1 joint) and below, all columns showed posterolaterally facing superior articular facets. The level of change in orientation, from posteromedial to posterolateral facing superior facets, was not constant and occurred anywhere between C4 (C3/C4 joint) and T1 (C7/T1 joint). The change in orientation followed 2 different patterns, i.e. sudden or gradual. The C6 vertebra (C5/C6 joint) was the most frequent site to show the transition. The shape of the superior articular facets was circular to oval at C3, C4 and C5 levels and gradually changed to a transversely elongated surface at C7 and T1. These findings correlate well with various cervical movements and associated clinical conditions.
Fast intracellular motion in the living cell by video rate reflection confocal laser scanning microscopy
Authors: VESELY PAVEL , BOYDE ALAN
Published: March 2003

Fast intracellular motion (FIM) was first revealed by back scattered light (BSL) imaging in video rate confocal scanning laser microscopy (VRCSLM), beyond the limits of spatial and temporal resolution obtainable with conventional optical microscopy. BSL imaging enabled visualisation of intra and extracellular motion with resolution in space down to 0.2 μm and in time to 1/25th of a second. Mapping the cell space at 0.2 μm×0.2 μm (XY = in instantaneous best focal plane)×0.5 μm (Z = height/depth, optic axis direction) volume steps revealed a communication layer above the known contact layer and an integrated dynamic spatial network (IDSN) towards the cell centre. FIM was originally observed as localised quasichaotic dancing (dithering) or reflecting patches/spots in the cell centre, faster in the darker nuclear space. Later, a second type of FIM was recognised which differed by the presence of a varied proportion of centrifugal and centripetal directional movements and/or jumping of patches/spots in the cell centre and outside the nuclear space. The first type is characteristic for cells in slightly adverse conditions while the second type has so far only been found in eutrophic cells. Temporal speeding up and coarsening of FIM, followed by slowing and eventually cessation at cell death, was found on exposure to strong stressors. It was concluded that the state of FIM provides instantaneous information about individual cell reactions to actual treatment and about cell survival. A putative switch between the first and second type FIM could be considered as an indicator of timing of cellular processes. The significance of FIM for the biology of the cell is seen in the rapid assessment of the condition of an individual live cell investigated by combination of various methods. Requirements for further development of this approach are outlined.
The differential distribution of acetylated and detyrosinated alpha‐tubulin in the microtubular cytoskeleton and primary cilia of hyaline cartilage chondrocytes
Authors: POOLE C. ANTHONY , ZHANG ZI‐JUN , ROSS JACQUELINE M.
Published: March 2003

The primary cilium is a ubiquitous cytoplasmic organelle of unknown function. Ultrastructural evidence of primary cilia in chondrocytes, and their colocalisation with the Golgi apparatus, has led to speculation that these structures are functionally linked. To investigate the relationship between these organelles, we examined the molecular anatomy of the microtubular cytoskeleton in the chondrocytes of chick embryo sterna. Thick cryosections were immunolabelled with antibodies directed against acetylated α‐tubulin (C3B9), detyrosinated α‐tubulin (ID5) and total α‐tubulin (TAT), and imaged at high magnification using confocal laser scanning microscopy. Transmission electron microscopy confirmed the ultrastructure of the chondrocyte primary cilium and its structural relationship to the Golgi apparatus. Detyrosinated and acetylated α‐tubulins were concentrated in the centrioles, centrosome and microtubule organising centre adjacent to the nucleus, with total α‐tubulin distributed throughout the cytoplasm. ID5 stained the primary cilium at an incidence of 1 per cell, its colocalisation with C3B9 identifying the primary cilium as one of the most stable features of the microtubular cytoskeleton. Primary cilia varied from 1 to 4 μm in length, and 3 patterns of projection into the extracellular matrix were identified; (1) full extension and matrix contact, with minor undulations along the length; (2) partial extension and matrix contact, with a range of bending deflections; (3) cilium reclined against the cell surface with minimal matrix contact. Ultrastructural studies identified direct connections between extracellular collagen fibres and the proteins which decorate ciliary microtubules, suggesting a matrix–cilium–Golgi continuum in hyaline chondrocytes. These results strengthen the hypothesis that the primary cilium acts as a ‘cellular cybernetic probe' capable of transducing environmental information from the extracellular matrix, communicating this information to the centrosome, and regulating the exocytosis of Golgi‐derived secretory vesicles.
Reversed palatal perforation by upper incisors in ageing blind mole‐rats (Spalax ehrenbergi)
Authors: ZURI I. , TERKEL J.
Published: March 2003

Blind mole‐rats (Spalax ehrenbergi) are fossorial solitary rodents that present striking morphological, physiological and behavioural adaptations to the subterranean environment in which they live. Previous studies have shown that mole‐rats are specialised in tooth‐digging. The rapid eruption‐rate of their incisors has evolved to compensate for their excessive wear by excavation. Males use their incisors more than females for digging and fighting, and their rate of incisor eruption is significantly more rapid than in females. Since mole‐rats use their incisors for digging throughout the year, we suggest that continuous mechanical pressure on their oral tissues concentrated at the apical sites of the upper incisors leads to cell and tissue fatigue. We provide evidence for 5 stages of palatal perforation by the upper incisors at their apical sites, with maximum perforation characterising aged males. Interspecies comparisons with 7 other fossorial and semi‐fossorial rodent species, and with beavers, which expose their incisors to enormous mechanical pressure, revealed that this palatal perforation is unique to the male mole‐rat. We suggest that while the fast eruption rate of incisors in the mole‐rat compensates for the rapid wear resulting from digging, evolutionary adaptation to continuous tooth‐digging is still ongoing, since the physical pressure of digging at the apical sites of the upper incisors leads to tissue destruction, breakage of the palatal bone and possibly to death, as a result of maxillary inflammation.
The function of the Periaxin gene during nerve repair in a model of CMT4F*
Authors: Williams Anna C. , Brophy Peter J.
Published: March 2003

Mutations in the Periaxin (PRX) gene are known to cause autosomal recessive demyelinating Charcot‐Marie‐Tooth (CMT4F) and Dejerine‐Sottas disease. The pathogenesis of these diseases is not fully understood. However, progress is being made by studying both the periaxin‐null mouse, a mouse model of the disease, and the protein–protein interactions of periaxin. L‐periaxin is a constituent of the dystroglycan–dystrophin‐related protein‐2 complex linking the Schwann cell cytoskeleton to the extracellular matrix. Although periaxin‐null mice myelinate normally, they develop a demyelinating peripheral neuropathy later in life. This suggests that periaxin is required for the stable maintenance of a normal myelin sheath. We carried out sciatic nerve crushes in 6‐week‐old periaxin‐null mice, and, 6 weeks later, found that although the number of myelinated axons had returned to normal, the axon diameters remained smaller than in the contralateral uncrushed nerve. Not only do periaxin‐null mice have more hypermyelinated axons than their wild‐type counterparts but they also recapitulate this hypermyelination during regeneration. Therefore, periaxin‐null mice can undergo peripheral nerve remyelination, but the regulation of peripheral myelin thickness is disrupted.
Astrocyte–endothelial interactions and blood–brain barrier permeability
Authors: Abbott N. J.
Published: March 2003

The blood–brain barrier (BBB) is formed by brain endothelial cells lining the cerebral microvasculature, and is an important mechanism for protecting the brain from fluctuations in plasma composition, and from circulating agents such as neurotransmitters and xenobiotics capable of disturbing neural function. The barrier also plays an important role in the homeostatic regulation of the brain microenvironment necessary for the stable and coordinated activity of neurons. The BBB phenotype develops under the influence of associated brain cells, especially astrocytic glia, and consists of more complex tight junctions than in other capillary endothelia, and a number of specific transport and enzyme systems which regulate molecular traffic across the endothelial cells (Abbott & Romero, Mol. Medical Today2, 1996). Transporters characteristic of the BBB phenotype include both uptake mechanisms (e.g. GLUT‐1 glucose carrier, L1 amino acid transporter) and efflux transporters (e.g. P‐glycoprotein, MRP). In addition to their role in long‐term barrier induction and maintenance, astrocytes and other cells can release chemical factors that modulate endothelial permeability over a timescale of seconds to minutes.

Cell culture models, both primary and cell lines, have been used to investigate aspects of barrier induction and modulation. Conditioned medium taken from growing glial cells can reproduce some of the inductive effects, evidence for involvement of diffusible factors. However for some features of endothelial differentiation and induction the extracellular matrix plays an important role. Several candidate molecules have been identified capable of mimicking aspects of glial–mediated barrier induction of brain endothelium; these include TGF(GDNF, bFGF, IL‐6 and steroids. In addition factors secreted by brain endothelial cells including leukaemia inhibitory factor (LIF) have been shown to induce astrocytic differentiation. Thus endothelium and astrocytes are involved in 2‐way mutual induction. Short‐term modulation of brain endothelial permeability has been shown for a number of small chemical mediators produced by astrocytes and other nearby cell types. Thus endothelial cells are involved in both long and short‐term chemical communication with neighbouring cells, with the perivascular end feet of astrocytes being of particular importance. The role of barrier induction and modulation in normal physiology and in pathology will be discussed.
Regional variations in the cellular matrix of the annulus fibrosus of the intervertebral disc
Authors: Bruehlmann Sabina B. , B. Rattner Jerome , R. Matyas John , A. Duncan Neil
Published: March 2003

The three‐dimensional architecture of cells in the annulus fibrosus was studied by a systematic, histological examination using antibodies to cytoskeletal components, in conjunction with confocal microscopy. Variations in cell shape, arrangement of cellular processes and cytoskeletal architecture were found both within and between the defined zones of the outer and inner annulus. The morphology of three, novel annulus fibrosus cells is described: extended cordlike cells that form an interconnected network at the periphery of the disc; cells with extensive, sinuous processes in the inner region of the annulus fibrosus; and cells with broad, branching processes specific to the interlamellar septae of the outer annulus. The complex, yet seemingly deliberate arrangement of various cell shapes and their processes suggests multiple functional roles. Regional variations in the organization of the actin and vimentin cytoskeletal networks is reported across all regions of the annulus. Most notable is the continuous, strand arrangement of the actin label at the disc's periphery in contrast to its punctate appearance in all other regions. The gap junction protein connexin 43 was found within cells from all regions of the annulus, including those which did not form physical connections with surrounding cells. These observations of the cellular matrix in the healthy intervertebral disc should contribute to a better understanding of site‐specific changes in tissue architecture, biochemistry and mechanical properties during degeneration, injury and healing.