The mechanics of mammalian intervertebral joints are complicated by the viscoelastic nature of the connective tissues joining vertebrae, and by multiple vertebral articulations and complex morphologies. Further, interspecific variation in these structures can greatly compound their functional variation between species, making comparative mechanical analyses even more difficult. Despite these sources of variation however, mammalian intervertebral joints universally exhibit a creep relaxation behaviour based on the viscoelastic nature of the soft tissue joint. We have evaluated, in 6 degrees of freedom, the mechanical signature of a novel mammalian lumbar intervertebral joint found in the Scutisorex spine, and compared it with a more typical mammalian joint in the Rattus (rat) lumbar spine. Scutisorex, the hero shrew, is an East African species of shrew with what is likely the most highly modified vertebral morphology in the entire history of mammals. Thus we decided to evaluate the mechanical behaviour of the intervertebral joint of this species, comparing it with a more representative mammal species in Rattus. We built a custom, 6 degrees of freedom, intervertebral joint transducer and a combined axial moment and load application system in order to quantify and compare the complex mechanical behaviour of these joints. Our results suggest that the Scutisorex joint is 5 times more resilient to simple axial torsion per body mass unit than Rattus, and that the complex load (combined axial compression and torsion) mechanical signature of Scutisorex is probably novel among all mammalian intervertebral joints. Under significant but physiological axial compression the Scutisorex intervertebral joint demonstrates no creep relaxation behaviour, simulating the mechanical behaviour of a rigid construct rather than a viscoelastic joint. The purpose of this rigid intervertebral joint in the ecology of Scutisorex remains unknown.

The lectin binding characteristics of mouse placental cells were examined. Wax embedded tissue sections of placentae from d 14 pregnant mice were stained with 26 lectins, with a wide range of sugar specificities. Cell cultures prepared from d 14 mouse placentae and cultured for 24 h were stained with 7 of the lectins to determine if they could be used as markers for the different trophoblast cells in culture. In tissue sections all placental cell populations bound lectin but no lectin bound specifically to any single trophoblast population. All the lectins which bound to layer 1 cytotrophoblast lining the maternal blood spaces of the labyrinthine placenta also bound to the fetal endothelium of the labyrinthine placenta. Binding of lectin appeared strongest on the adluminal membrane of these cell populations suggesting a role for the carbohydrate moieties in nutrient transfer. Few lectins bound to junctional zone trophoblast. Overall, the binding of lectin to cultured cells did not correlate exactly with lectin binding to the cell populations in tissue sections. The value of lectins as markers for placental cells in culture was therefore found to be limited. Our findings indicate that carbohydrate expression by at least some placental cells may vary in culture from that expressed by the cells in vivo with obvious concerns for the validity of functional in vitro studies.

The ultrastructure of the olfactory mucosa of the armadillo Dasypus hybridus was studied. A comparison with the olfactory mucosa of another armadillo (Chaetophractus villosus) was made. The olfactory mucosa of D. hybridus shows many features which are similar to those of other mammals. Interestingly, it differs from the olfactory mucosa of the armadillo C. villosus. A suggestion is made that these differences may be due to differences in the digging habits of these species. In Dasypus, the supporting cells (SCs) showed dense vacuoles, multivesicular bodies and lysosome-like bodies probably related with the endocytotic system. The SCs show a dense network of SER presumably associated with xenobiotic mechanisms. The olfactory receptor neurons exhibit lysosome-like bodies and multivesicular bodies in their perikarya. These organelles suggest the presence of an endocytotic system. Duct cells of Bowman's glands exhibit secretory activities. Bowman's glands are compound-branched tubulo-acinar mixed glands with merocrine secretory mechanisms.

Despite the fact that development of the human embryo heart is of considerable clinical importance, there is still disagreement over the process and the timing of events. It is likely that some of the conflicting accounts may have arisen from difficulties in describing and visualising 3-dimensional structures from 2-dimensional sections. To help overcome this problem and to improve our understanding of the development of the heart, we have devised techniques for the production of interactive 3D models reconstructed from serial histological sections of human embryos. Our method uses commercial software designed for the creation of 3D models and virtual reality environments. The ability to construct interactive visual images which both illustrate and communicate complex 3D information contributes to our understanding of the complex developmental changes occurring in embryogenesis.

The crush model of injury in skeletal muscle is widely used in the investigation of tissue degeneration and regeneration. Previously, such trauma has been induced by using forceps to crush the muscle, commonly applying sufficient pressure to bring the mid-arms of the forceps together. This report introduces a reliable electromechanical device designed to generate reproducible focal lesions in skeletal muscle of mice. The tibialis anterior was crushed in 17 young adult mice. Two days after injury, the muscles were examined microscopically. By morphometric analysis, it was determined that the volumes of the lesions produced were similar (mean 0.499 mm3±0.098, range 0.278−0.601 mm3), and that the full extent of the damaged muscle was easily distinguished and readily quantifiable. This will allow a more precise comparison in future investigations into regenerative differences between age groups, satellite cell activation and the inflammatory response.

Navicular bones from the 4 limbs of 95 horses, classified in 9 categories, were studied. The anatomical bases were established for the morphometry of the navicular bone and its variations according to the category of horse, after corrections were made for front or rear limb, sex, weight, size and age. In ponies, navicular bone measurements were smallest for light ponies and regularly increased with body size, but in horses, navicular bone dimensions were smallest for the athletic halfbred, intermediate for draft horse, thoroughbreds and sedentary halfbreds and largest for heavy halfbreds. The athletic halfbred thus showed reduced bone dimensions when compared with other horse types. Navicular bones from 61 horses were studied histomorphometrically. Light horses and ponies possessed larger amounts of cancellous bone and less cortical bone. Draft horses and heavy ponies showed marked thickening of cortical bone with minimum intracortical porosity, and a decrease in marrow spaces associated with more trabecular bone. Two distinct zones were observed for the flexor surface cortex: an external zone composed mainly of poorly remodelled lamellar bone, disposed in a distoproximal oblique direction, and an internal zone composed mainly of secondary bone, with a lateromedial direction for haversian canals. Flexor cortex external zone tended to be smaller for heavy ponies than for the light ponies. It was the opposite for horses, with the largest amount of external zone registered for draft horses. In athletic horses, we observed an increase in the amount of cortical bone at the expense of cancellous bone which could be the result of reduced resorption and increased formation at the corticoendosteal junction. Cancellous bone was reduced for the athletic horses but the number of trabeculae and their specific surfaces were larger. Increased bone formation and reduced resorption could also account for these differences.

Thymic epithelial cells are an important source of cytokines and other regulatory peptides which guide thymocyte proliferation and maturation. Parathyroid hormone-related protein (PTHrP), a cytokine-like peptide, has been reported to affect the proliferation of lymphocytes in vitro. The studies presented here were undertaken to test the hypotheses that PTHrP is produced locally within the thymus where it could influence thymocyte maturation and, more specifically, that thymic epithelial cells (TEC) could be the intrathymic source of PTHrP expression. To this end, immunohistochemical studies were performed to localise PTHrP and the PTH/PTHrP receptor within the adult rat thymus. Antibodies directed against 2 different PTHrP epitopes, PTHrP(1–34) and PTHrP(34–53), demonstrated prominent specific PTHrP immunoreactivity in both subcapsular and medullary TEC. In addition, faint but specific staining for PTHrP was seen in the cortex, interdigitating between cortical lymphocytes while sparing epithelial-free subcapsular areas, thus suggesting that cortical TEC could also be a source of PTHrP immunoreactivity. In contrast, PTH/PTHrP receptor immunoreactivity was only seen in medullary and occasional septal TEC; no evidence of cortical or lymphocytic PTH/PTHrP receptor immunoreactivity was detected. Immunohistochemical studies of cultured cytokeratin-positive rat TEC confirmed the results of these in situ studies as cultured TEC were immunoreactive both for PTHrP and the PTH/PTHrP receptor. Thus these results demonstrate that PTHrP is produced by the epithelial cells of the mature rat thymus. This suggests that PTHrP, a peptide with known cytokine, growth factor and neuroendocrine actions, could exert important intrathymic effects mediated by direct interactions with TEC, or indirect effects on PTH/PTHrP receptor-negative thymocytes.

The immunohistochemical location of glial fibrillary acidic protein (GFAP) was used to study the state of maturation of retinal astrocytes from an 18-mo-old infant and to compare it with the situation in the adult. Infant astrocytes showed intense GFAP immunoreactivity in the perikarya and possessed spindle-like enlargements in their processes, while in the adult immunoreactivity in the perikarya was scarce and the spindle-like enlargements were not evident. Two types of astrocyte were observed in adult and child retinas: elongated and star-shaped. In the adult, the star-shaped type tend to be more stylised and to have longer processes than in the infant. In the infant, numerous astrocyte cell bodies were observed over vessels, while in the adult these were scarce. In the infant, the star-shaped astrocytes made up a honeycomb plexus, but this was not fully developed. These results suggest that at 18 mo of postnatal development the retinal astrocytes are still increasing and growing into the astroglial structure found in adults.

The aim of this study was to describe the course of the buccal nerve and its relationships with the temporalis muscle during the prenatal period. Serial sections of 90 human fetal specimens ranging from 9 to 17 wk development were studied by light microscopy. Each fetal specimen was studied on both right and left sides, making a total of 180 cases for study. A 3-D reconstruction of the region analysed in one of the specimens was made. In 89 cases the buccal nerve was located medial to the temporalis muscle; in 73 cases it penetrated the muscle; in 15 cases it lay in a canal formed by the muscle fibres and was covered by fascia, and finally, in 3 cases it was a branch of the inferior alveolar nerve. The study has revealed that in a large number of cases the buccal nerve maintains an intimate association with the temporalis muscle.

A spectrum of limb abnormalities ranging from adactyly, syndactyly, acrosyndactyly to nail hypoplasia was encountered in mouse embryos subjected to amniotic sac puncture at the corresponding gestational stage when human chorionic villus sampling (cvs) would normally be performed clinically. Previous skeletal studies revealed that, apart from the occasional incidence of fusion of 2 distal phalanges, syndactyly usually only affected the soft tissues within the interdigital spaces. A similar situation was also observed in cases of adactyly; while the skeletal elements of the digits were present, the soft tissues in the interdigital spaces failed to separate. A transient period of bradycardia is induced, possibly secondary to compression of the embryo by the extraembryonic membranes and uterine muscles following amniotic sac puncture. These factors, we believe, produce temporary hypoxia/ischaemia of the distal extremities, and may lead to the modification of the interdigital mesenchymal tissues within the autopods. In order to investigate the mechanism(s) underlying soft tissue syndactyly, limbs recovered at 0.5, 4, 8, 12, 24, or 36 h following amniotic sac puncture (ASP) were examined histologically. Vascular disruption in the form of localised areas of haemorrhage, vascular dilatation and congestion and the presence of fluid-filled cavities occurred in relation to the marginal vein and vascular plexus in the interdigital spaces. It is hypothesised that this interfered with the normal equilibrium of the preset programs of mitosis/cell death and apoptosis within the mesenchymal cells of the interdigital spaces. Apoptosis in these areas was inhibited in the majority of the experimental limbs analysed 4 h after ASP. Instead of undergoing necrosis/apoptosis, increased mitotic activity was usually observed from 8 h following ASP at the sites where apoptosis would normally be expected to be seen. The aberrant fate of the interdigital mesenchyme following ASP and the underlying mechanism(s) involved are discussed, as is the critical importance of an adequate vascular supply to the interdigital spaces during the morphogenesis of the autopod. We believe that this report contributes to understanding the mechanism(s) which lead to syndactyly following ASP, and the limb defects occasionally seen following cvs when this is undertaken during early gestation.

Ovaries from adult cycling rats were studied from 1600 h on the day of prooestrus to 0700 h on the day of oestrus in order to relate the cyclic hormonal changes to the proliferative activity of preovulatory and postovulatory (i.e. newly-formed corpora lutea) follicles. Proliferative activity was studied by the immunohistochemical demonstration of DNA-incorporated 5-bromodeoxyuridine (BrdU). The proliferative activity of granulosa cells (GC) in large preovulatory follicles showed a centripetal pattern and decreased during prooestrus, reaching a minimum at 2100 h. However, a proliferative wave was found in the GC of preovulatory follicles at 0200 h on the day of oestrus and in those of newly-formed corpora lutea at 0700 h on the day of oestrus. These results suggest that the granulosa cells of preovulatory follicles show maturational changes that followed a different pattern, depending on their location within the follicle, and that the proliferative wave found from 0200 to 0700 h on oestrus is important for the establishment of the number of steroidogenic cells in the cyclic corpus luteum.

Some 30 lectins in combination with glycosidase digestion and immunohistochemistry with 5 antibodies directed against antigens of the ABO and Lewis blood group systems were used to analyse the distribution and synthesis of glycoconjugates in the epithelium of the large airways in man. Both mucous gland cells and goblet cells were labelled by 12 of 30 lectins and by the antibodies, dependent on the ABO, Lewis, and secretor status. The corresponding binding patterns of the serous gland cells differed markedly from those of goblet and mucous gland cells and in general were not dependent on the ABO, Lewis, and secretor status. After digestion with neuraminidase and fucosidase, binding of soy bean agglutinin and peanut agglutinin to goblet and mucous gland cells was increased. Binding of peanut agglutinin to serous gland cells was stronger only after the digestion with neuraminidase. Digestion with O-glycosidase after the use of neuraminidase or fucosidase resulted in a decrease of peanut agglutinin binding to goblet and mucous gland cells. The present results show that the secretory products of goblet and mucous gland cells on the one hand and those of serous cells on the other differ considerably with respect to their terminal glycosylation. The glycosyltransferases coded by genes of the ABO and Lewis blood group and secretor systems are active only in goblet and mucous gland cells, resulting in the presence of the corresponding antigens. Precursor substances of blood group antigens types 1, 2, and 3 are found only in these cell types. In serous gland cells, blood group systems do not influence the glycosylation of glycoproteins. The results of the digestion with O-glycosidase indicates the presence of O-glycosylation in mucous gland and goblet cells, but not in serous gland cells.

Methods to quantify trabecular orientation are crucial in order to assess the exact trajectory of trabeculae in anatomical and histological sections. Specific methods for evaluating trabecular orientation include the ‘point counting’ technique (Whitehouse, 1974), manual tracing of trabecular outlines on a digitising board (Whitehouse, 1980), textural analysis (Veenland et al. 1998), graphic representation of vectors (Shimizu et al. 1993; Kamibayashi et al. 1995) and both mathematical (Geraets, 1998) and fractal analysis (Millard et al. 1998). Optical and computer-assisted methods to detect trabecular orientation of bone using the Fourier transform were introduced by Oxnard (1982) later refined by Kuo & Carter (1991) (see also Oxnard, 1993, for a review), in the analysis of planar sections of vertebral bodies as well as in planar radiographs of cancellous bone in the distal radius (Wigderowitz et al. 1997). At present no studies have applied this technique to 2-D images or to the study of dried bones. We report a universal computer-automated technique for assessing the preferential orientation of the tibial subarticular trabeculae based on Fourier analysis, emphasis being placed on the search for improvements in accuracy over previous methods and applied to large stereoscopic (2-D) fields of anatomical sections of dried human tibiae. Previous studies on the trajectorial architecture of the tibial epiphysis (Takechi, 1977; Maquet, 1984) and research data about trabecular orientation (Kamibayashi et al. 1995) have not employed Fourier analysis.

In the human oviduct epithelium during ciliogenesis, short tubular structures were found in the transitional zone between the basal body and cilium. The tubules, termed transitional tubules from their location, were 34–36 nm in diameter and 0.13±0.06 μm in length; the number around a basal body was variable, but usually 4–6. The cytoplasmic leaflets of the tubule membranes were coated by electron-dense material and appeared to be connected to alar sheets. The transitional tubules existed transiently during ciliogenesis. The exact role of transitional tubules is unknown, but considering their location, they may fix the basal body in the apical cytoplasm during ciliary elongation and/or may be related to formation of alar sheets.

A correspondence item entitled ‘A warning against revival of the classic tenets of gross anatomy related to nerve–muscle specificity’ was recently published in the Journal of Anatomy (Shinohara, 1996a). The present correspondent fully agrees with some aspects of his opinion, in particular, the 3 laws about applications which he described, and he also appreciates his approach to the argument based on the results of embryology and experimentation. However, his denial of morphological interpretations based on the theory of nerve–muscle specificity may be due to an incomplete understanding of the current status of the theory.

The histological changes in hair follicles in hairless rats derived from the Wistar strain (hW, hairless Wistar) were examined from birth to maturity and compared with those of age-matched normal Wistar rats. In the 1st hair cycle, the hair follicles of hW rats were shorter and less well developed than those of Wistar rats. In early anagen, eosinophilic bodies were observed in some hair follicles which showed immature histological features. By using Tdt-mediated dUTP nick end labelling (TUNEL) method and electron microscopic examination, these bodies were confirmed to be apoptotic bodies. These follicles seemed to disappear by abnormal regression. In late anagen phase, the follicles in which the apoptosis did not occur showed enlarged hair roots with hypertrophy of the inner root sheath. Subsequently, when the follicles in normal Wistar rats synchronously regressed in the catagen phase, most of the follicles in hW rats similarly entered the catagen phase, but a few follicles did not regress completely and showed aberrant hair root enlargement. Finally, both types of follicle in hW rats formed follicular cysts. These abnormalities in follicle development (abnormal follicular regression and follicular cyst formation) appear to be associated with the hairlessness in this rat strain.

The ulnar tunnel is located at the proximal part of the hand radial to the pisiform bone and to the proximal part of the carpal tunnel. Inside it lie the ulnar nerve and artery. Compression of the ulnar nerve in this tunnel is often reported. Cysts, occupational trauma, fractures and muscle variations are among the main causes (Schjelderup, 1964; Kleinert & Hayes, 1971). Damage to the ulnar nerve and artery during the endoscopic decompression of the carpal tunnel has been reported recently (Agee et al. 1992; Nath et al. 1993; De Smets & Fabry, 1995). The structures within the ulnar tunnel are closely related to the medial part of the flexor retinaculum, in particular the ulnar artery which is located lateral to the ulnar nerve. During a study of this region we found a rare disposition of the contents of this tunnel. We believe that knowledge of this variation is important for the surgical anatomy of this region.

Corpuscular nerve endings in the nasal respiratory mucosa of the dog were investigated by immunohistochemical staining specific for protein gene product 9.5 by light and electron microscopy. In the nasal respiratory mucosa, complex corpuscular endings, which displayed bulbous, laminar and varicose expansions, were distributed on the dorsal elevated part of the nasal septum and on the dorsal nasal concha. The endings were 300–500 μm long and 100–250 μm wide. Some axons gave rise to a single ending while others branched into 2 endings. Cryostat sections revealed that the corpuscular endings were located within the nasal respiratory epithelium. On electron microscopy, immunoreactive nerve terminals that contained organelles, including mitochondria and neurofilaments, were observed within the epithelial layer near the lumen of the nasal cavity. Some terminals contacted the goblet cell. Such terminal regions were covered by the cytoplasmic process of ciliated cells and were never exposed to the lumen of the nasal cavity. These nerve endings are probably activated by pressure changes.