To guide surgery of nerves that traverse and surround the tympanic cavity in the rat, anatomical illustrations are required that are topographically correct. In this study, maps of this area are presented, extending from the superior cervical ganglion to the otic ganglion. They were derived from observations that were made during dissections using a ventral approach. Major blood vessels, bones, transected muscles of the tongue and neck and supra and infrahyoid muscles serve as landmarks in the illustrations. The course of the mandibular, facial, glossopharyngeal, vagus, accessory and hypoglossal nerves with their branches, and components of the sympathetic system, are shown and discussed with reference to data available in the literature. Discrepancies in this literature can be clarified and new data are presented on the trajectories of several nerves. The course of the tympanic nerve was established. This nerve originates from the glossopharyngeal nerve, enters the tympanic cavity, crosses the promontory, passes the tensor tympani muscle dorsally, and continues its route intracranially to the otic ganglion as the lesser petrosal nerve after intersecting with the greater petrosal nerve. Auricular branches of the glossopharyngeal and of the vagus nerve were noted. We also observed a pterygopalatine branch of the internal carotid nerve, that penetrates the tympanic cavity and courses across the promontory.

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.

Granulated metrial gland (GMG) cells differentiate in the uterine wall in pregnancy in mice but the mechanisms which control their differentiation and maintenance are unknown. In vivo, GMG cells share an intimate association with fibroblast-like stromal cells. The importance of this association has been assessed by examining the effects of withdrawal of stromal cell contact on GMG cell maintenance in vitro. When single cell suspensions of cells were prepared from mouse metrial glands there was a steady decline in numbers with days of culture but usually some remained at 7 d of culture. The ability of metrial gland cells to kill Wehi 164 target cells in 51Cr-release cytotoxicity assays was retained by cells cultured for at least 3 d. When explants of metrial gland were maintained in culture to allow GMG cell migration onto the culture flask, the attached GMG cells were lost by 1 d later. Overall, these results suggest that a juxtacrine regulatory mechanism maintains GMG cells. The rapid loss of unsupported GMG cells in culture has major implications in the design of assays to examine GMG cell function.

To clarify the nature of M cells, the detailed ultrastructural characteristics and lectin-binding properties of M cells were investigated in follicle-associated epithelium (FAE) of chicken caecal tonsils. M cells presented various outlines from columnar to dome shaped. Their polymorphism was dependent on the number of harboured intraepithelial migrating cells. The lighter and larger nuclei of M cells were situated at more apical levels in the epithelial lining compared with those of neighbouring microvillous epithelial cells. The microvilli, which were significantly shorter and thicker than those of adjacent microvillous epithelial cells, were sparsely distributed or completely absent on the apical surfaces of M cells. In general, the apical cytoplasm of M cells without microvilli protruded slightly into the intestinal lumen. Numerous small vesicles were often contained in the apical cytoplasm. The numerous small invaginations of the apical and lateral cell surfaces suggested active transportation of luminal substances. No canaliculi existed in the apical cytoplasm of M cells whereas they were often detected in the neighbouring microvillous epithelial cells. A noteworthy finding was the frequent detection of multivesicular bodies in the apical cytoplasm of M cells. These multivesicular bodies suggest some degradation of ingested luminal substances during transcytoplasmic transportation. WGA and 4 other lectins strongly reacted with all epithelial cells except for M cells, this negativity suggesting a means of detecting M cells in chicken caecal tonsils. Three lectins, DSL, ConA and Jacalin, reacted weakly with the glycocalyx on M cells. The positive reactivity might allow chicken M cells to be utilised for specific antigen delivery into the mucosal immune system in some parenteral vaccinations.

In human placenta, 3D spatial relationships between villi and the maternal vascular bed determine intervillous porosity and this, in turn, influences haemodynamics and transport. Recently-developed stereological methods were applied in order to examine and quantify these relationships. Placentas were collected after 37 wk from control pregnancies and those associated with maternal diabetes mellitus classified according to duration and severity (White classification scheme). Two principal questions were addressed: (1) are normal spatial arrangements maintained in well-controlled diabetes mellitus? and (2) do arrangements vary between diabetic groups? To answer these questions, tissue sections cut at random positions and orientations were generated by systematic sampling procedures. Volume densities of villi (terminal+intermediate), intervillous spaces and perivillous fibrin-type fibrinoid deposits were estimated by test point counting and converted to global volumes after multiplying by placental volumes. Design-based estimates of the sizes (volume- and surface-weighted volumes) of intervillous ‘pores’ were obtained by measuring the lengths of point- and intersection-sampled intercepts. From these, theoretical numbers of pores were calculated. Model-based estimates (cylinder model) of the hydraulic diameters and lengths of pores were also made. Second-order stereology was used to examine spatial relationships within and between villi and pores and to test whether pair correlation functions deviated from the value expected for ‘random’ arrangements. Estimated quantities did not differ significantly between diabetic groups but did display some departures from control values in non-insulin-dependent (type 2) diabetic placentas. These findings support earlier studies which indicate that essentially normal microscopical morphology is preserved in placentas from diabetic subjects with good glycaemic control. Therefore, it is likely that fetal hypoxia associated with maternal diabetes mellitus is due to metabolic disturbances rather than abnormalities in the quantities or arrangements of maternal vascular spaces.

Four human soft palate muscles, and palatopharyngeus, the uvula, the levator and tensor veli palatini were examined using enzyme-histochemical, immunohistochemical and biochemical methods and compared with human limb and facial muscles. Our results showed that each palate muscle had a distinct morphological identity and that they generally shared more similarities with facial than limb muscles. The palatopharyngeus and uvula muscles contained 2 of the highest proportions of type II fibres ever reported for human muscles. In contrast, the levator and tensor veli palatini muscles contained predominantly type I fibres. A fetal myosin heavy chain isoform (MyHC), not usually found in normal adult limb muscles, was present in a small number of fibres in all palate muscles. The mean muscle fibre diameter was smaller than in limb muscles and the individual and intramuscular variability in diameter and shape was considerable. All palate muscles had a high capillary density and an unusually high mitochondrial enzyme activity in the type II fibres, in comparison with limb muscles. No ordinary muscle spindles were observed. The fibre type and MyHC composition indicate that the palatopharyngeus and uvula muscles are functionally involved in quick movements whereas the levator and tensor veli palatini muscles perform slower and more continuous contractions. The high aerobic capacity and the rich capillarisation suggest that the palate muscles are relatively fatigue resistant. Absence of ordinary muscle spindles indicates a special proprioceptive control system. The special morphology of the palate muscles may be partly related to the unique anatomy with only one skeletal insertion, a feature consistent with muscle work at low load and tension and which may influence the cytoarchitecture of these muscles. Other important factors determining the special morphological characteristics might be specific functional requirements, distinct embryological origin and phylogenetic factors.

The structure and vascular pattern of the human tibialis anterior tendon was investigated using injection techniques, light and transmission electron microscopy and immunohistochemistry. From the well vascularised peritenon, blood vessels penetrate the tendon tissue and anastomose with a longitudinally oriented intratendinous network. The distribution of blood vessels within the tibialis anterior tendon was not homogenous. The posterior part of the tendon had a complete vascular network that extends from the musculotendinous junction to the insertion at the first metatarsal and medial cuneiform bones. In the anterior half, the tissue was avascular in a zone with a length of 45–67 mm. This zone was covered by a single layer (∼30 μm) of oval shaped cells. Transmission electron microscopy showed that these cells have the characteristics of chondroid cells. This region was stained by Alcian blue at pH 1 which indicates a high concentration of acid glycosaminoglycans and immunohistochemical staining for chondroitin-4-sulphate, chondroitin-6-sulphate and aggrecan was positive. However, immunostaining for the typical cartilage specific type II collagen within this zone was negative. The location of the avascular zone corresponds to the region where the tibialis anterior tendon wraps around the superior and inferior retinacula which serve as fibrous pulleys. This is the region where most spontaneous ruptures of the tibialis anterior tendon occur. The presence of fibrocartilage within gliding tendons is a functional adaptation to compressive and shearing forces. In contrast to reports from the literature about the structure of gliding tendons wrapping around a bony pulley, the gliding zone of the tibialis anterior tendon has only a narrow layer of chondroid cells and proof of type II collagen is lacking.

Variations in the branching pattern of the common hepatic artery often occur and may be encountered during cholecystectomy. Variants of the cystic artery, its branches and relations with the biliary structures and blood vessels emphasise the importance of arterial dissection in biliary surgery. In this study, a rare variant of the cystic artery and its choledochal branch is described. The cystic artery arose from the gastroduodenal artery, passed anterior to structures in the free margin of lesser omentum and travelled a long distance before supplying the gall bladder. A long choledochal branch was noted accompanying the common bile duct. Surgical implications of this variation of the cystic and choledochal arteries are discussed.

For an accurate assessment of jaw movement, it is crucial to understand the comprehensive formation of the masticatory muscles with special reference to the relationship to the disc of the temporomandibular joint. Detailed dissection was performed on 26 head halves of 14 Japanese cadavers in order to obtain precise anatomical information of the positional relationships between the masticatory muscles and the branches of the mandibular nerve. After complete removal of the bony elements, the midmedial muscle bundle in all specimens and the discotemporal muscle bundle in 6 specimens, derivatives of the temporalis, which insert into the disc were observed. On the anterior area of the articular capsule and the disc of the temporomandibular joint, the upper head of the lateral pterygoid, the midmedial muscle bundle of temporalis and the discotemporal bundle of temporalis were attached mediolaterally, and in 3 specimens the posterosuperior margin of the zygomaticomandibularis was attached to the anterolateral area of the disc. It is suggested that these muscles and muscle bundles contribute to various mandibular movements. Although various patterns of the positional relationships between the muscles and muscle bundles and the their innervating nerves are observed in the present study, relative positional relationships of the muscles and muscle bundles and of nerves of the mandibular nerve are consistent. A possible scheme of the developmental formation of the masticatory muscles based on the findings of the positional relationships between the muscles and the nerves is presented.

The variations which occur in the medial and lateral ligament complexes of the elbow were investigated. These occurred frequently with the standard appearances occurring in no more than half the specimens on the medial side and one quarter of those on the lateral side. Surgeons who regularly perform elbow arthroplasty must be aware of these considerations, especially with the introduction of unconstrained prostheses which rely upon the ligament complex for their postoperative stability.

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.

Tooth germs of upper first molars of 1, 3, and 5-d-old rats, fixed in formaldehyde, were stained for the detection of apoptosis by the TUNEL method, and by the azo-dye method for the demonstration of acid phosphatase. For conventional light and electron microscopy the specimens were fixed in glutaraldehyde- formaldehyde and embedded in glycol methacrylate and Araldite. Results showed that macrophages, present in the stellate reticulum, contained basophilic bodies and TUNEL-positive globules, i.e. apoptotic bodies, in their interior. Macrophages also possessed strong acid phosphatase activity. Electron microscopy showed the presence of large vacuoles inside the macrophages containing dense fragmented material. Taken together these results suggest that the intra-epithelial macrophages of the stellate reticulum engulf apoptotic bodies.

Development of desmin-positive hepatic stellate cells was studied in mice using double immunofluorescent techniques and in vitro cultures with special attention given to their cell lineages. Several studies recently reported on the presence of cells that are immunologically reactive with both antidesmin and anticytokeratin antibodies in young fetal rat livers, and suggested the possibility that these cells give rise to hepatocytes and hepatic stellate cells. At early stages of mouse liver development, stellate cells with desmin-positive filaments were scattered in the liver parenchyma. However, the stellate cells definitely differed from hepatoblasts and hepatocytes in terms of their morphology and expression of desmin and hepatoblast and hepatocyte-specific E-cadherin in the liver. Fetal hepatoblasts and hepatocytes did not react with antidesmin antibodies, nor did desmin-positive stellate cells express E-cadherin in vivo and in vitro. Thus it is likely that desmin-positive stellate cells and hepatoblasts belong to different cell lineages. In the fetal liver, the desmin-positive stellate cells surrounded blood vessels, and extended their processes to haematopoietic cells and megakaryocytes. Many, but not all, hepatoblasts and hepatocytes were observed to be associated with the stellate cells. At fetal stages, cellular processes positive for desmin in the stellate cells were also thick compared with those in the adult liver, in which desmin-positive stellate cells lay in Disse's space and were closely associated with all hepatocytes. These developmental changes in the geography of desmin-positive cells in the liver parenchyma and their morphology may be associated with their maturation and interactions with other cell types.

Mean glomerular volume has previously been estimated, using stereological techniques, specifically the point-sampled intercept (PSI), either from isotropic or from vertical sections. As glomeruli are approximately spherical structures, the same stereological technique was carried out on vertical and arbitrary sections to determine whether section orientation had any effect on mean glomerular volume estimation. Equine kidneys from 10 individuals were analysed using the PSI method of estimating volume-weighted mean glomerular volume (MGV); for each kidney, arbitrary and vertical sections were analysed. MGVs were not significantly different between arbitrary and vertical sections (P = 0.691) when analysing the data with the paired t test; when plotting MGV estimates from arbitrary sections against those from vertical sections the intercept was found not to be significantly different from zero (P > 0.8) and the slope of the regression line not to be significantly different from 1.0 (P > 0.4). For the estimation of MGV in equine kidneys using PSI, arbitrary sections may be used if it is not possible to use isotropic or vertical sections, but some caution must be exercised in the interpretation of results so gained.

There are limited data detailing the pattern of age and gender-related changes to the thoracic vertebral bodies and intervertebral discs. A retrospective MR investigation, involving T1-weighted midsagittal images from 169 cases, was undertaken to examine age influences on the anterior wedge (anteroposterior height ratio or Ha/Hp), biconcavity (midposterior height ratio or Hm/Hp), and compression indices (posterior height/anteroposterior diameter or Hp/D) of the thoracic vertebral bodies. Disc degenerative changes in the annulus, nucleus, end-plate and disc margin were noted on T2-weighted sagittal images for the 169 cases, based on a 3-level grading system. A linear age-related decline in the Ha/Hp and Hm/Hp indices was noted. The Hp/D index increased during the first few decades of life, then decreased gradually thereafter. The prevalence of abnormal findings in the annuli, nuclei and disc margins increased with increasing age, particularly in the mid and lower thoracic discs. Greater disc degenerative changes were observed in males. These findings provide further insight into the nature of thoracic vertebral shape changes across the lifespan, and the typical patterns of degeneration of the thoracic intervertebral discs.

The lingulae of both sides of 165 dry adult human mandibles, 131 males and 34 females of Indian origin, were classified by their shape into 4 types: 1, triangular; 2, truncated; 3, nodular; and 4, assimilated. Triangular lingulae were found in 226 (68.5%) sides, truncated in 52 (15.8%), nodular in 36 (10.9%) and assimilated in 16 (4.8%) sides. Triangular lingulae were found bilaterally in 110, truncated in 23, nodular in 17 and assimilated in 7 mandibles. Of the remaining 8 mandibles with different appearances on the 2 sides, 6 had a combination of triangular and truncated and 2 had nodular and assimilated. The incidence of triangular and assimilated types in the male and female mandibles are almost equal. In the truncated type it was double in the male mandibles while the nodular type was a little less than double in the female mandibles.

To assess the contribution of apoptosis to the mechanism of synovial joint cavitation, and to clarify morphological cellular changes during cavitation, we investigated the development of the rat knee joint by light and electron microscopy, TUNEL methods, and electrophoresis of DNA fragments. Although cavitation occurred within the interzone, which consists of 2 outer and a middle layer termed the intermediate zone, no morphological or biochemical signs of cell death, in particular apoptosis, were seen in the interzone at any embryonic stage. Microscopic and ultrastructural alterations affecting cell differentiation were clearly observed in the interzone, i.e. mesenchymal cells gradually showed elongation, cytoplasmic vacuolation and pyknosis in the intermediate zone where the elongated cells were arranged in parallel in some strata. Some of these cells were further flattened into spindle cells and the number of strata decreased to 2. The rest of the cells were incorporated secondarily into the outer layers, becoming chondroblasts. Collagen fibrils were arranged in a network structure in the outer layers, which obviously differed from the directional pattern parallel to the long axis of elongated cells in the intermediate zone. In addition, the density of collagen fibrils was higher in the outer layers than in the intermediate zone. During cavitation, the initial separation was detected between the elongated cells in the intermediate zone in paraffin sections at E16.5 and the spindle cells in epoxy sections at E18.5. The spindle cells lining the cavity, namely, the surfaces of the epiphysis and meniscus, finally became chondrocytes. The diminution of proteoglycans and collagen fibrils and the synthesis of hyaluronan in the extracellular matrix are now generally believed to be parts of the mechanism for cavitation based on the concept of ‘loss of cohesion’. The microscopic and ultrastructural alterations in the interzone seemed to reflect differences in the arrangement and density of collagen fibrils and the developmental condition of the extracellular matrix between layers. Also it did not seem likely that these alterations inhibit the synthesis of hyaluronan at the presumptive joint line because this synthesis takes place at the plasma membrane. Separation between spindle cells should therefore represent the mechanism for developmentally programmed cavitation. Reorganization of the extracellular matrix is probably necessary for the cellular metamorphoses in the interzone involved in the process of cavitation.