Adult mandibles of 317 modern humans and 91 great apes were selected that showed no pathology. Adult mandibles of Pan troglodytes troglodytes, Pongo pygmaeus pygmaeus and Gorilla gorilla gorilla and from 2 modern human populations (Zulu and Europeans from Spitalfields) were reliably sexed. Thirteen measurements were defined and included mandibular height, length and breadth in representative positions. Univariate statistical techniques and multivariate (principal component analysis and discriminant analysis) statistical techniques were used to investigate interspecific variability and sexual dimorphism in human and great ape mandibles, and intraspecific variability among the modern human mandibles. Analysis of interspecific differences revealed some pairs of variables with a tight linear relationship and others where Homo and the great apes pulled apart from one another due to shape differences. Homo and Pan are least sexually dimorphic in the mandible, Pan less so than Homo sapiens, but both the magnitude of sexual dimorphism and the distribution of sexually dimorphic measurements varied both among and between modern humans and great apes. Intraspecific variation among the 10 populations of modern humans was less than that generally reported in studies of crania (74.3% of mandibles were correctly classified into 1 of 10 populations using discriminant functions based on 13 variables as compared with 93% of crania from 17 populations based on 70 variables in one extensive study of crania). A subrecent European population (Poundbury) emerged as more different from a recent European population (Spitalfields) than other more diverse modern populations were from each other, suggesting considerable morphological plasticity in the mandible through time. This study forms a sound basis on which to explore mandibular variation in Neanderthals, early Homo sapiens and other more ancient fossil hominids.

Angiogenesis is essential for the replacement of cartilage by bone during growth and repair. In order to obtain a better understanding of the mechanisms regulating vascular invasion at sites of endochondral ossification we have investigated the expression of the endothelial cell-specific mitogen, vascular endothelial growth factor (VEGF), by chondrocytes in human neonatal growth plates. VEGF was absent from chondrocytes in the resting zone and only weakly expressed by occasional chondrocytes in the proliferating region. In the hypertrophic zone the number of chondrocytes stained and the intensity of staining for VEGF increased with chondrocyte hypertrophy, maximum expression of VEGF being observed in chondrocytes in the lower hypertrophic and mineralised regions of the cartilage. These observations provide the first demonstration of the presence of VEGF in situ in developing human bone and are consistent with in vitro observations demonstrating the upregulation of proangiogenic growth factor production with increasing chondrocyte hypertrophy. The presence of numerous small blood vessels and vascular structures in the subchondral region where VEGF expression was maximal indicates that VEGF produced by hypertrophic chondrocytes may play a key role in the regulation of vascular invasion of the growth plate.

The objective of this study was to investigate the normal distribution of cartilage thickness in the major joints of the lower limb in elderly individuals. A 12.5 MHz ultrasound transducer was used to measure the cartilage thickness in the right and left hip, knee and ankle joint of 10 individuals aged between 62 and 99 y. Distribution patterns of cartilage thickness were derived by b-spline interpolation and the average distribution computed in each surface. The maximum cartilage thickness in the hip joint was 2.6 (±0.36) mm and the mean thickness 1.3 (±0.17) mm. The CV% (a measure of thickness inhomogeneity within the joint surface) was 32%. In the knee, the maximal and mean values were 3.8 (±0.46) mm and 1.9 mm (±0.24) mm, respectively (CV%=34%), and in the ankle 1.7 (±0.25) mm and 1.0 (±0.16) mm (CV%=32%). Systematic differences existed between both sides in the knee, the distal femur showing a significantly greater thickness on the right. While the mean and maximal thicknesses were systematically higher in the knee than in the hip, and in the hip higher than in the ankle (P<0.05), there were no systematic differences in the thickness inhomogeneity of the 3 joints. Only the malleolus showed a somewhat more uniform thickness than the other joint surfaces. The variablity between individuals was similar for all joints for mean thickness, but the interindividual variability of the maximal thickness values was highest in the knee and lowest in the ankle. Whereas the cartilage thickness distributions in the joints of the lower limb have been suggested to reflect the pressure distribution within the articular surface, the absolute thickness is proposed to be a function of dynamic loading (range of motion) during gait, rather than being a reflection of the static articular pressure.

Metalloenzymes have an important role in repair and regenerative processes in skin wounds. Demands for different enzymes vary according to the phase in the healing cascade and constituent events. Sequential changes in the concentrations of calcium, copper, magnesium and zinc were studied in the incisional wound model in the rat over a 10 d period. Copper levels remained low (<10 μg/g dry weight) throughout, but calcium, magnesium and zinc increased from wounding and peaked at about 5 d at a time of high inflammation, granulation tissue formation and epidermal cell proliferation. Metal concentrations declined to normal by 7 d when inflammation had regressed, re-epithelialisation of the wound site was complete and the ‘normalisation’ phase had commenced. Although the wound was overtly healed by 10 d, the epidermis was still moderately hyperplastic. In view of competitive binding of trace metals at membrane receptors and carrier proteins, the ratios or balance between these trace metals was examined and the significance is discussed. Using immunocytochemistry, we demonstrated increases in metallothionein immunoreactivity as an indication of zinc and copper activity in the papillary dermis and in basal epidermal cells near the wound margin 1–5 d after wounding. This is consistent with metalloenzyme requirements in inflammation and fibrogenesis. Calmodulin, a major cytosolic calcium binding protein was highest in maturing keratinocytes and in sebaceous gland cells of normal skin; it was notably more abundant in the epidermis near the wound margin and in re-epithelialising areas at a time when local calcium levels were highest.

Skeletal muscle has the unique ability to increase the rate of oxygen usage during contraction. This has led several workers to suggest that by-products of this increased oxygen consumption, oxygen-derived free radicals, may be primarily responsible for exercise-induced damage to skeletal muscle. However, because of this rapidly changing redox state, skeletal muscle has developed a number of different endogenous mechanisms which adapt rapidly following a period of exercise. These include numerous structural and biochemical changes such as increased muscle activity of antioxidant enzymes and content of stress or heat shock proteins (HSPs). This adaptation is associated with protection against the potentially damaging effects of a second period of exercise. In addition, we have recently demonstrated a significant increase in free radical production during a period of nondamaging exercise, which is rapidly followed by a significant increase in the expression of antioxidant enzymes and HSPs, suggesting that a change in redox state of the muscle may act as signal for adaptation.

We have compared the distribution, numbers and volume of mucous glands in the tracheas of 11 mammalian species. No glands were present in the rabbit. The mouse only contained glands at the border between the trachea and larynx. In the rat, glands were commonest in the cephalad third of the trachea, but on average were much scarcer than in the larger species. Between species, there was a significant correlation between airway diameter and gland volume per unit surface area, suggesting that the rate of deposition of inhaled particles may increase in large airways. In the ventral portion of the trachea of about half the species, the glands were concentrated between the cartilaginous rings; in others they were evenly distributed over and between the rings. In most species in which the trachealis muscle attached to the internal surface of the cartilaginous rings, the glands were external to the muscle. In all species in which the muscle attached to the external surface of the cartilaginous rings, the glands were internal to the muscle. In the ox, goat, dog and sheep, the volume of glands per unit tracheal surface area was markedly greater in the ventral than the dorsal aspect of the trachea. The reverse was true of the pig. In humans, gland density in the 2 regions was similar. The frequency of gland openings was determined in the ox, goat, pig, dog and sheep tracheas, and ranged from 0.3 per mm2 in the dorsal portion of the sheep trachea to 1.5 per mm2 in the ventral portion of the ox trachea. For these 5 species, the volume of gland acini per unit luminal surface area varied linearly with the numbers of gland openings, with the volume of individual glands being constant at ∼ 120 nl.

Here we present ideas connecting the behaviour of the cranial neural crest during development with the venerable, perhaps incorrect, view that gill-supporting cartilages of an ancient agnathan evolved into the skeleton of an early gnathostome's jaw. We discuss the pattern of migration of the cranial neural crest ectomesenchyme in zebrafish, along with the subsequent arrangement of postmigratory crest and head mesoderm in the nascent pharyngeal segments (branchiomeres), in diverse gnathostomes and in lampreys. These characteristics provide for a plausible von Baerian explanation for the problematic inside-outside change in topology of the gills and their supports between these 2 major groups of vertebrates. We consider it likely that the jaw supports did indeed arise from branchiomeric cartilages.

Oligodendrocytes, derived from stem cell precursors which arise in subventricular zones of the developing central nervous system, have as their specialist role the synthesis and maintenance of myelin. Astrocytes contribute to the cellular architecture of the central nervous system and act as a source of growth factors and cytokines; microglia are bone-marrow derived macrophages which function as primary immunocompetent cells in the central nervous system. Myelination depends on the establishment of stable relationships between each differentiated oligodendrocyte and short segments of several neighbouring axons. There is growing evidence, especially from studies of glial cell implantation, that oligodendrocyte precursors persist in the adult nervous system and provide a limited capacity for the restoration of structure and function in myelinated pathways damaged by injury or disease.

Schwann cells are excluded from the CNS during development by the glial limiting membrane, an area of astrocytic specialisation present at the nerve root transitional zone, and at blood vessels in the neuropil. This barrier, however, can be disrupted and, with the highly migratory nature of Schwann cells, can result in their invasion and myelination of the CNS in many pathological situations. In this paper we demonstrate that this occurs in a number of myelin mutants, including the myelin deficient (md) and taiep rats and the canine shaking (sh) pup. While it is still relatively uncommon in the rodent mutants, the sh pup shows extensive Schwann cell invasion along the neuraxis. This invasion involves the spinal cord, brain stem, and cerebellum and increases in amount and distribution with age. In situ hybridisation studies using a P0 riboprobe suggest that the likely origin of these cells in the sh pup is the nerve roots, primarily the dorsal roots. Paradoxically, Schwann cell myelination of the CNS increases with time in the sh pup despite a marked, progressive gliosis involving the glia limitans and neuropil. Thus the mechanism by which these cells migrate into the CNS through the gliosed nerve root transitional zone or from vasa nervorum remains unknown. Extensive Schwann cell CNS myelination may have therapeutic significance in human myelin disease.

Data on femoral neck-shaft angles were collected for 30 modern, historic and prehistoric human population samples, and analysed with respect to sexual dimorphism, bilateral asymmetry, geographical patterning and general economic level. Although some samples had modest sexual dimorphism in this angle, and some individuals exhibited clear asymmetry, there were no consistent patterns of sexual or side differences across human populations. Similarly, there was no evidence for geographic differences, since broad regional groups lacked significant differences and mean angles were not correlated with latitude. However, there is a significant increase in mean neck-shaft angles across populations with an increasingly sedentary existence and with mechanisation. The last reflects the developmental plasticity of this feature with respect to habitual load levels during ontogeny of the hip region.

There is an accumulating body of evidence suggesting that the periaqueductal grey (PAG) is involved in the pathophysiology of migraine. Positron emission tomography (PET) studies in humans have shown that the caudal ventrolateral midbrain, encompassing the ventrolateral PAG, has activations during migraine attacks. The PAG may well be involved not only through the descending modulation of nociceptive afferent information, but also by its ascending projections to the pain processing centres of the thalamus. In this study the intranuclear oncogene protein Fos was used to mark cell activation in the PAG following stimulation of the trigeminally-innervated superior sagittal sinus (SSS) in both cats and in nonhuman primates (Macaca nemestrina). Fos expression in the PAG increased following stimulation to a median of 242 cells (interquartile range 236–272) in the cat and 155 cells (range 104–203) in the monkey, compared with control levels of 35 cells (21–50) and 26 cells (18–33), respectively. Activation was predominantly in the ventrolateral area of the caudal PAG suggesting that the PAG is involved following trigeminally-evoked craniovascular pain.

Experimental animal models are frequently used to study articular cartilage, but the relevance to man remains problematic. In this study animal models were compared by examination of the collagen fibre arrangement in the medial tibial plateau of human, cow, pig, dog, sheep, rabbit and rat specimens. 24 cartilage samples from each species were prepared and maximum cartilage thickness in the central tibial plateau measured. Samples were fixed, dehydrated, freeze-fractured and imaged by scanning electron microscopy (SEM). At low magnification, 2 different arrangements of collagen fibres were observed: leaf-like (human, pig, dog) and columnar (cow, sheep, rabbit, rat). The porcine collagen structure was the most similar to that of man. This arrangement was consistent from the radial to the upper zones. Under higher magnification at the surface of the leaves, the collagen was more randomly oriented, whereas the columns consisted of parallel collagen fibrils. The maximum thickness of cartilage did not correlate with the type of collagen arrangement but was correlated with the body weight of the species (r=0.785). When using animal models for investigating human articular cartilage function or pathology, the differences in arrangement of collagen fibres in tibial plateau cartilage between laboratory animals should be considered especially if morphological evaluation is planned.

This study was prompted by the prospect of transgenic pigs providing donor hearts for transplantation in human recipients. Autonomic innervation is important for the control of cardiac dynamics, especially in the conduction system. Our objective was to assess the relative distribution of autonomic nerves in the pig heart, focusing initially on the conduction system but addressing also the myocardium, endocardium and epicardium (see Crick et al. 1999). Quantitative immunohistochemical and histochemical techniques were adopted. All regions of the conduction system possessed a significantly higher relative density of the total neural population immunoreactive for the general neuronal marker protein gene product 9.5 (PGP 9.5) than did the adjacent myocardium. A similar density of PGP 9.5-immunoreactive innervation was observed between the sinus node, the transitional region of the atrioventricular node, and the penetrating atrioventricular bundle. A differential pattern of PGP 9.5-immunoreactive innervation was present within the atrioventricular node and between the components of the ventricular conduction tissues, the latter being formed by an intricate network of Purkinje fibres. Numerous ganglion cell bodies were present in the peripheral regions of the sinus node, in the tissues of the atrioventricular groove, and even in the interstices of the compact atrioventricular node. Acetylcholinesterase (AChE)-containing nerves were the dominant subpopulation observed, representing 60–70% of the total pattern of innervation in the nodal tissues and penetrating atrioventricular bundle. Tyrosine hydroxylase (TH)-immunoreactive nerves were the next most abundant neural subpopulation, representing 37% of the total pattern of innervation in the compact atrioventricular node compared with 25% in the transitional nodal region. A minor population of ganglion cell bodies within the atrioventricular nodal region displayed TH immunoreactivity. The dominant peptidergic nerve supply possessed immunoreactivity for neuropeptide Y (NPY), which displayed a similar pattern of distribution to that of TH-immunoreactive nerve fibres. Calcitonin gene-related peptide (CGRP)-immunoreactive nerves represented 8–9% of the total innervation of the nodal tissues and penetrating atrioventricular bundle, increasing to 14–19% in the bundle branches. Somatostatin-immunoreactive nerve fibres were relatively sparse (4–13% of total innervation) and were most abundant in the nodes, especially the compact atrioventricular node. The total pattern of innervation of the porcine conduction system was relatively homogeneous. A substantial proportion of nerve fibres innervating the nodal tissues could be traced to intracardiac ganglia indicative of an extensive intrinsic supply. The innervation of the atrioventricular node and ventricular conduction tissues was similar to that observed in the bovine heart, but markedly different to that of the human heart. It is important that we are aware of these findings in view of the future use of transgenic pig hearts in human xenotransplantation.

The projections of different subpopulations of myenteric neurons in the mouse small and large intestine were examined by combining immunohistological techniques with myotomy and myectomy operations. The myotomies were used to examine the polarity of neurons projecting within the myenteric plexus and showed that neurons containing immunoreactivity for nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), calbindin and 5-HT projected anally, while neurons with substance P (SP)-immunoreactivity projected orally, in both the small and large intestine. Neurons containing neuropeptide Y (NPY)- and calretinin-immunoreactivity projected locally. In the large intestine, GABA-immunoreactive neurons projected both orally and anally, with more axons tending to project anally. Myectomy operations revealed that circular muscle motor neurons containing NOS/VIP/±NPY and calretinin neurons projected anally both in the small and large intestine, while SP-immunoreactive circular muscle motor neurons projected orally. In the large intestine, GABA-IR circular muscle motor neurons projected both orally and anally. This study showed that although some neurons, such as the NOS/VP inhibitory motor neurons and interneurons, SP excitatory motor neurons and 5-HT interneurons had similar projections to those in other species, the projections of other chemical classes of neurons in the mouse intestine differed from those reported in other species.

The bicuspid (mitral) valve complex of the human heart consists of functional units which include the valve leaflets, chordae tendineae and the papillary muscles. The mechanical properties of these functional units depend to a large extent on the link between the muscle and the valve. This link is usually arranged in a branching network of avascular tendinous chordae composed of collagen and elastic fibres, which transmit contractions of the papillary muscle to the valve leaflets. In order to perform their function efficiently, the chordae have to possess a high degree of elasticity, as well as considerable strength and endurance. Human chordae tendineae originating from the left ventricles were obtained from 7 embalmed cadavers and 6 postmortem subjects of various ages. Samples washed in saline were fixed or postfixed in 9% formol saline. Observations were made by illuminating the chordae along their axes. The reflected images originating from the superficial collagenous layers of the relaxed chordae showed a striped pattern 11 μm in width. Scanning electron and light microscopy of the chordae confirmed an undulating pattern of collagen fibrils arranged in bundles of planar waves in register and around the entire circumference of the chorda. The dimensions of the waves correlated with those of the striped reflected pattern. The observed undulating arrangement of the collagen fibrils appears to produce an inherent built-in elasticity which is likely to be of considerable advantage for a tissue which is under continuous repetitive stress. The chordae were covered by endocardium composed of a superficial layer of smooth squamous endothelial cells and an underlying dense layer of elastic fibres. It is suggested that the relaxed striped chordae, consisting of undulating collagen fibrils, straighten when the chordae become stretched by papillary muscle contraction, thereby mitigating the peak stress developed during muscle contraction. On relaxation the elastic tissue tends to return the collagen to its wavy configuration. It is also suggested that the regular wavy pattern of collagen seen in young individuals gradually changes with age by elongation of the wave pattern which eventually becomes randomised. In addition, with increasing age, substantial cushions of connective tissue appear below endocardium while the dense collagenous core has a reduced cross-sectional area which may lead to stretching and eventual rupture of the chordae.

En bloc staining with basic fuchsin is an established method for demonstrating microdamage in bone. Using transmitted light microscopy, variations in light intensity, depth of focus and magnification are necessary to distinguish fully-stained microcracks generated in vivo, from partially-stained or unstained artefactual cracks due to cutting and machining. This process is both difficult and time-consuming. In this study, 2 methods were used to examine fuchsin-stained microcracks in human rib sections, transmitted light and epifluorescence microscopy. No differences were found in crack number, density or length between the 2 methods indicating comparable accuracy. Using green epifluorescence, only microcracks containing fuchsin fluoresced orange against the darkfield background, enabling unstained, artefactual cracks to be screened out. Under UV epifluorescence, microcracks stained through the full 100 μm depth of the section fluoresced purple. Partially-stained artefactual cracks failed to fluoresce and were screened out. Epifluorescence is a simple, rapid and accurate screening method for differentiating fully-stained from artefactual microcracks in bone.

The desired properties required for successful embalming of cadavers for gross anatomy teaching include: (1) good long-term structural preservation of organs and tissues with minimal shrinkage or distortion; (2) prevention of over-hardening, while maintaining flexibility and suppleness of internal organs; (3) prevention of desiccation; (4) prevention of fungal or bacterial growth and spread within a specific cadaver and to other cadavers in the dissection room; (5) reduction of potential biohazards (spread of infection to dissection personnel and students); (6) reduction of environmental chemical hazards (especially from formaldehyde and phenol) in order to comply with increasingly severe health and safety regulations and a new awareness of possible dangers of these chemicals in the workplace; and (7) retention of colour of tissues and organs while minimising oxidation effects that result in ‘browning’.

GABA (gamma-amino-butyric acid) is the predominant neurotransmitter in the mammalian suprachiasmatic nucleus (SCN), with a central role in circadian time-keeping. We therefore undertook an ultrastructural analysis of the GABA-containing innervation in the SCN of mice and rats using immunoperoxidase and immunogold procedures. GABA-immunoreactive (GABA-ir) neurons were identified by use of anti-GABA and anti-GAD (glutamic acid decarboxylase) antisera. The relationship between GABA-ir elements and the most prominent peptidergic neurons in the SCN, containing vasopressin-neurophysin (VP-NP) or vasoactive intestinal polypeptide (VIP), was also studied. Within any given field in the SCN, approximately 40–70% of the neuronal profiles were GABA-ir. In GABA-ir somata, immunogold particles were prominent over mitochondria, sparse over cytoplasm, and scattered as aggregates over nucleoplasm. In axonal boutons, gold particles were concentrated over electron-lucent synaptic vesicles (diameter 40–60 nm) and mitochondria, and in some instances over dense-cored vesicles (DCVs, diameter 90–110 nm). GABA-ir boutons formed either symmetric or asymmetric synaptic contacts with somata, dendritic shafts and spines, and occasionally with other terminals (axo-axonic). Homologous or autaptic connections (GABA on GABA, or GAD on GAD) were common. Although GABA appeared to predominate in most neuronal profiles, colocalisation of GABA within neurons that were predominantly neuropeptide-containing was also evident. About 66% of the VIP-containing boutons and 32% of the vasopressinergic boutons contained GABA. The dense and complex GABAergic network that pervades the SCN is therefore comprised of multiple neuronal phenotypes containing GABA, including a wide variety of axonal boutons that impinge on heterologous and homologous postsynaptic sites.

A number of reports suggest that the process of ageing impairs wound repair and that strategies to manipulate the age-related wound healing environment are necessary in order to stimulate repair. The process of cutaneous wound repair is controlled by growth factors in an autocrine and paracrine fashion: it is therefore surprising that the localisation of specific growth factors and their receptors has not been documented in wound healing with respect to chronological age. In this study the temporal profile of growth factor and receptor immunostaining was assessed within acute incisional wounds in an ageing mouse colony. A delay in appearance of platelet derived growth factor (PDGF) A and B isoforms, and PDGF-α and -β receptors was evident with increasing animal age, paralleled by a similar finding for epidermal growth factor (EGF) and EGF receptor. Transforming growth factor (TGF)-7beta;1 and 2 isoforms were increased at all time points in the wounds of younger animals, but the TGF-β3 isoform increased in intensity from d 7 postwounding in the old mice wounds, and basic fibroblast growth factor (bFGF) from d 14. The quantity and distribution patterns of the various growth factors and their receptors may explain the age-related differences in wound healing speed and quality, and possibly suggest new therapeutic targets for manipulating wound healing in the aged.

A precise knowledge of the anatomy of the paranasal sinuses is essential for the clinician. Conventional radiology does not permit a detailed study of the nasal cavity and paranasal sinuses, and has now largely been replaced by computerised tomographic (CT) imaging. This gives an applied anatomical view of the region and the anatomical variants that are very often found. The detection of these variants to prevent potential hazards is essential for the use of current of endoscopic surgery on the sinuses. In the present work, we have studied the anatomical variants observed in the nasal fossae and paranasal sinuses in 110 Spanish subjects, using CT in the coronal plane, complemented by horizontal views. We have concentrated on the variants of the nasal septum, middle nasal concha, ethmoid unciform process and ethmoid bulla, together with others of lesser frequency. The population studied showed great anatomical variability, and a high percentage (67%) presented one or more anatomical variants. Discounting agger nasi air cells and asymmetry of both cavities of the sphenoidal sinus, which were present in all our cases, the variations most often observed were, in order, deviation of the nasal septum, the presence of a concha bullosa, bony spurs of the nasal septum and Onodi air cells.