Design-based stereology is employed to estimate total numbers of myocyte nuclei and mean myocyte volume per nucleus in ventricles of fetal and early postnatal human hearts. Organs were collected postmortem from subjects varying in age from 16 gestational wk to 40 postnatal wk. Numbers of myocyte nuclei per unit volume of ventricle were estimated using physical disectors (parallel pairs of sections). Absolute numbers were calculated by multiplying nuclear packing densities by ventricular volumes estimated from ventricular mass and tissue density. Volumes per nucleus were obtained via estimates of the combined volumes of all myocytes (or of the myocardium as a whole) and the numbers of myocyte nuclei. The findings showed that numbers of myocyte nuclei increase linearly from 16 wk towards term. They were also consistent with the notion that hyperplasia ceases abruptly at birth or soon afterwards. The net rate of production of myocyte nuclei was about 38×107/wk (2.3 million nuclei/h). The total volume of myocytes continued to expand in the same way from 16 wk to at least 35 wk of gestation. Published studies on the incidence of binucleate myocytes during early postnatal growth of the ventricles of rats suggest that the volume of a myocyte doubles prior to nuclear division. Prenatal growth in the human heart is consistent with this mechanism. Myocardial hypertrophy after birth must occur by cellular hypertrophy without karyokinesis.

Rat liver ultrastructure was investigated after partial hepatectomy (PH), by scanning and transmission electron microscopy. Portal pressure was monitored before and after PH and, after killing performed at 6, 12, 24, 48 h and 10 d, regenerating livers were fixed by portal vein perfusion under haemodynamic conditions identical to those existing in vivo. An early and persistent increase in portal pressure after PH was found (P<0.01 for normal vs sham-operated controls). Ultrastructural study showed sinusoid dilatation and disappearance of the sieve-plate arrangement of small endothelial pores, thus leaving the parenchymal liver cell surface directly exposed to portal blood. Widening of sinusoids, endothelial fenestrations, intercellular spaces and spaces of Disse, was accompanied by dilatation of bile canaliculi. At 10 d, liver ultrastructure had returned to normal. Our observations suggest that a rise in portal pressure, as a consequence of PH, may be related to the observed ultrastructural changes in the liver.

Expression of surfactant proteins SP-A, SP-B and the transcription factors TTF-1 and HNF-3β was identified by immunohistochemistry in the developing chicken. SP-B, a small hydrophobic peptide critical for lung function and surfactant homeostasis in mammals, was detected in the epithelial cells of parabronchi in embryonic chicken lung from the 15th day of incubation, prior to the onset of the breathing movements and was expressed at high levels in the posthatching chicken lung. SP-A, an abundant surfactant protein involved in innate defence of the mammalian lung, was detected in the chick embryo in subsets of epithelial cells in the mesobronchus, starting from d 15 and was detected in the posthatching chicken lung. The transcription factors hepatocyte nuclear factor 3β (HNF-3β) and thyroid transcription factor-1 (TTF-1), both regulators epithelial cell differentiation and gene expression in mammalian species, were detected at the onset of lung bud formation (d 4 of incubation) and throughout lung development. Abundant nuclear expression was detected in nuclei of respiratory epithelial cells of developing bronchial tubules for both transcription factors. In contrast to the surfactant proteins, expression of both TTF-1 and HNF-3β decreased markedly in posthatching chicken lung. The expression of SP-A and SP-B in chick lung demonstrates the conservation of surfactant proteins in vertebrates. The temporospatial pattern of TTF-1 and HNF-3β overlaps with that of SP-A and SP-B, supporting their potential roles in chick lung development and demonstrating the conservation of regulatory mechanisms contributing to gene expression in respiratory epithelial cells in vertebrates.

Retrograde tracing with Fluoro-Gold was used to identify the complete population of knee joint afferents in the lumbar dorsal root ganglia of adult female Wistar rats. There was an average of 581±31 (mean±S.D.) afferents supplying each joint. These were found distributed from L1 to L5 with the great majority localised in the L3 and L4 ganglia. Electron microscopy of the posterior articular nerve of the knee revealed an average of 103±15 (mean±S.D.) myelinated and 513±39 unmyelinated axonal profiles. Since about 50–60% of the unmyelinated profiles would be expected to be sympathetic efferents, these numbers are consistent with the numbers of afferents found by Fluoro-Gold retrograde tracing and suggest that the posterior articular nerve contains about 50% of the total number of knee joint afferents in the rat. Immunohistochemistry revealed that an average of 10% of identified joint afferents expressed substance P-like immunoreactivity and that 33% expressed calcitonin gene-related peptide-like immunoreactivity.

Serial transverse histological sections of the human craniovertebral junction (CVJ) of 4 normal human embryos (aged 45 to 58 d) and of a fetus (77 d) were used to create 3-dimensional computer models of the CVJ. The main components modelled included the chondrified basioccipital, atlas and axis, notochord, the vertebrobasilar complex and the spinal cord. Chondrification of the component parts of CVJ had already begun at 45 d (Stage 18). The odontoid process appeared to develop from a short eminence of the axis forming a third occipital condyle with the caudal end of the basioccipital. The cartilaginous anterior arch of C1 appeared at 50–53 d (Stages 20–21). Neural arches of C1 and C2 showed gradual closure, but there was still a wide posterior spina bifida in the oldest reconstructed specimen (77 d fetus). The position of the notochord was constant throughout. The normal course of the vertebral arteries was already established and the chondrified vertebral foramina showed progressive closure. The findings confirm that the odontoid process is not derived solely from the centrum of C1 and that there is a ‘natural basilar invagination’ of C2 during normal embryonic development. On the basis of the observed shape and developmental pattern of structures of the cartilaginous human CVJ, we suggest that certain pathologies are likely to originate during the chondrification phase of development.

The architecture of the fetal villous tree and its vasculature in the bovine placentome were studied in the second half of gestation using both conventional histology and histology of ink-filled blood vessels. These were compared with corrosion casts of plastic fillings of the vasculature, prepared for scanning electron microscopy. This combination of morphological methods allows perception of the villous tree throughout gestation from broad-conical to tall-conical form where branch ramification occurs mainly at right angles to the stem. The stem villus typically contains a single central artery and several peripheral veins arranged in parallel. The proximal branches to the stem, the intermediate villi, contain a central arteriole and accompanying venules. The distal branches, the terminal villi, enclose capillary convolutions which consist of an afferent arterial capillary limb, capillary loops and efferent venous capillary limbs. Vascular interconnections exist within the terminal villi, as capillaries or venules between the capillary convolutions, serially bridging them in up to 5 places, and as capillary anastomoses between the capillary loops. Coiling and sinusoidal dilatations of these loops develop near the end of gestation. The intraplacentomal rearrangement of villous trees with progressive gestation and their morphological vascular adaptations are discussed in relation to placental function, including the ever increasing need for transplacental substance exchange. This adaptation allows the blood to traverse the shortest possible arterioarteriolar route to the periphery of the trees where exchange takes place. The need for an increasing blood flow stimulates capillary growth and at the same time optimises the blood flow reaching the placental barrier represented by the vessel cast surface. The capillaries also carry the blood back into the very voluminous system of venules and veins where back diffusion may occur. The total volume of terminal villi of bovine placentome, the ‘working part’ of villous trees, hence distinctly increases with respect to the stem and intermediate villi, the ‘supplying part’ of the villous tree. In morphological terms the efficiency of the bovine transplacental diffusional exchange is higher than in the closely related ‘co-ruminants’ sheep and goats and distinctly higher when compared with the human placenta.

The stimulation or ablation of cerebellar structures has produced a variety of visceral responses, indicating a cerebellar role in visceral functions. Studies using anterograde and retrograde tracing methods have revealed connections between the hypothalamus and cerebellar structures. The aim of this study is to investigate the cerebellar connections of the dorsomedial (DMH) and posterior hypothalamic nuclei using retrograde axonal transport of horseradish peroxidase (HRP). In the present study, micro-injection of HRP restricted within the borders of the DMH showed that the projections of this nucleus are not uniform throughout its extent. The posterior DMH receives projections from the cerebellum, whereas the anterior DMH does not. These projections were from the (greatest to least concentration) lateral (dentate), anterior interposed (emboliform), and medial (fastigial) cerebellar nuclei. In addition, both the anterior and posterior DMH receive projections from various areas of the brainstem which confirms earlier studies and provides detailed descriptions. This study also demonstrates the distribution of labelled neurons to cerebellar and brainstem nuclei following HRP injection into the posterior hypothalamic nucleus. It provides clear evidence for a direct cerebellar nuclei-posterior DMH and cerebellar nuclei-posterior hypothalamic nucleus connections. We suggest that the brainstem reticular nuclei and other connections, such as the solitary, trigeminal and vestibular nuclei, of both DMH and posterior hypothalamus may contribute to the indirect cerebellohypothalamic connections. These observations offer a new perspective on the question of how the cerebellum may influence autonomic activity.

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.

In the absence of a systematic morphometric study of Onuf's nucleus in man, this investigation defines the limits of variation of segmental position and the range of length and volume of Onuf's nucleus in 6 normal humans displaying no neurological disease (2 males, 4 females). Serial section reconstruction methods in conjunction with the disector method provided information on the numbers, sizes and shapes of the constituent motor neurons of Onuf's nucleus. In contrast to previous descriptions, the cranial origin of Onuf's nucleus occurred in rostral S1 in 50% of subjects, and midcaudal S1 in the remaining subjects. Onuf's nucleus varied in length between 4 and 7 mm, and was 0.2–0.37 mm3 in volume. Differences in length or volume between males or females, or between the left and right side of the cord were not statistically significant. Neurons in Onuf's nucleus varied in diameter between 10 μm and 60 μm (mean 26 μm) and their mean number was 625±137. A higher density of neurons occurred at the cranial and caudal ends of the nucleus relative to the middle. While 37% of neurons were approximately spherical (shape index ∼1), 44% were ellipsoid and 19% fusiform (shape indices varying between 0.26 and 0.8). These findings are compared with previous studies of Onuf's nucleus in man and animals. The results form a basis for further studies on Onuf's nucleus in normality and neurodegenerative diseases.

Muscle fibre type composition and distribution in the biceps brachii (long head) and triceps brachii (long head) of the rat and rabbit were investigated using the following histochemical techniques: myosin ATPase, with preincubation at pH 10.4 and 4.35; succinate dehydrogenase (SDH) and glycogen phosphorylase. The muscle fibres were classified into slow-twitch (SO), fast-twitch glycolytic (FG), fast-twitch oxidative glycolytic (FOG and FOg) and fast-twitch oxidative fibres (FO). Significant differences in the regional distribution of muscle fibre types have been observed between the rat and the rabbit. In the rat, SO fibres were restricted to the deep regions of both biceps and triceps brachii, whereas FG fibres were located in the intermediate and superficial regions (the superficial regions contained the highest percentages of FG fibres). In the rabbit, SO and FG fibres were spread over the entire muscle, although SO and FG fibres were most abundant in the deep and superficial regions respectively. These findings indicate that the biceps and triceps brachii are more regionalised in the rat than in the rabbit.

In 1813 Gantzer described 2 accessory muscles in the human forearm which bear his name (Wood, 1868; Macalister, 1875; Testut, 1884; Le Double, 1897). The more frequent of the 2 accessory muscles or ‘accessorius ad pollicem’ was found to arise from the coronoid process of the ulna, coursing distally to attach into the flexor pollicis longus muscle (flexor pollicis longus accessory head, FPLah). The less frequently observed or ‘accessorius ad flexorem profundum digitorum’ was again found to arise from the coronoid process and course to join into the flexor digitorum profundus (flexor digitorum profundus accessory head, FDPah). Since their initial description, they have been examined in further detail by a number of authors (Wood, 1868; Macalister, 1875; Le Double, 1897; Dykes & Anson, 1944; Mangini, 1960; Malhotra et al. 1982; Dellon & McKinnon, 1987; Kida, 1988). These studies, most of them focusing on the FPLah, all show different results of prevalence, origin, insertion, relations and nerve supply. We undertook this study with the aim of providing a more accurate account of the detailed morphology of both accessory muscles because of the above-mentioned inconsistent anatomical descriptions and the lack of information as to important aspects such as vascular supply, morphology (shape and length) and the coexistence of both accessory heads.

This study describes the gross anatomy of the alimentary tract of Houbara Bustards (Chlamydotis undulata macqueenii), Kori Bustards (Ardeotis kori), Rufous-crested Bustards (Eupodotis ruficrista) and White-bellied Bustards (Eupodotis senegalensis) maintained in captivity by the National Avian Research Center in the United Arab Emirates. The morphology of the alimentary tract and the proportions of each region were similar in all 4 species. The length of the oesophagus, combined proventriculus and ventriculus, small intestine, and large intestine formed 24.2–28.4%, 7.3–9.7%, 40.5–55.1% and 9.1–14.7% of the total alimentary tract length respectively. Neither crop nor oesophageal enlargement was observed in the birds examined in this study, although male Kori Bustards possessed a saccus oralis in the oropharyngeal cavity. Oesophagi, proventriculi, ventriculi, caeca and large intestine were well developed in all species. The small intestine was shorter than that of other avian herbivores and granivores when compared on a bodyweight basis. The well differentiated stomachs and well developed caeca of the bustards examined in this study are characteristic of omnivores. Analysis of the mean lengths of the alimentary tract components and weight of the liver and pancreas showed sexual dimorphism in cases where male and female data were available for direct comparison.

The purpose of this study was to quantify and map the gross fibre architecture of the cranial dura mater (CDM) using small angle light scattering (SALS). In SALS, HeNe laser light is passed through the tissue, and the resultant scattering pattern is analysed to determine the preferred fibre direction and degree of orientation. The dura mater was found to be a complex structure with fibre orientations ranging from highly aligned to nearly random. In the temporal region, 80% of the samples (n=20) were found to have regions composed of highly oriented fibres with a mean fibre direction of 6.3°±0.8° with respect to the sagittal plane (i.e. almost parallel to the superior sagittal sinus). These highly aligned regions were found in symmetric anatomical locations about the median sagittal sinus and had similar fibre orientations over both hemispheres. Although our sample size was small, we found that the size of the symmetric regions, which covered 14.4±1.6% of the total CDM area, was not influenced by subject's age or sex. The presence of these highly oriented fibre regions in CDM may be due to mechanical forces exerted on dura mater during its development. These forces may have induced realignment of the collagen fibres in the direction of tensile pull, although the exact basis for the unique gross fibre architecture of CDM remains unknown.

Morphological features of the cap enameloid and dental epithelial cells were investigated by light and transmission electron microscopy during the various stages of enameloid mineralisation and early maturation in the tilapia. The pattern of mineralisation along collagen fibrils in the enameloid differed from that in the dentine. Many matrix vesicles were found in the predentine and in the enameloid, suggesting that they may be involved in the initial mineralisation in both regions. Most of the organic matrix disappeared from the cap enameloid during mineralisation and maturation. The disappearance of the organic matrix could be divided into 2 stages. Initially a fine network-like matrix, which probably consisted of glycosaminoglycans and extended between collagen fibrils, began to disappear. At the same time, fine crystallites and electron-dense, fine granular material covered the collagen fibrils as mineralisation of the enameloid began. In the second stage, the maturation of the enameloid, the collagen fibrils degenerated completely and disappeared from the cap enameloid, being replaced by large numbers of large crystals. At the mineralisation stage, the numbers of lysosomal bodies tended to increase in the inner dental epithelial (IDE) cells, which contained a well developed Golgi apparatus and rough endoplasmic reticulum (rER). At the early stage of maturation, a ruffled border was noted at the distal ends of the IDE cells, which contained many mitochondria and lysosomal bodies, but less rER. These features suggest that the cells actively absorb the organic matrix, which includes collagen fibrils, in the cap enameloid. The outer dental epithelial (ODE) cells were translucent cells that contained well developed labyrinthine canalicular spaces from the onset of the mineralisation stage to the middle stage of maturation. The IDE and ODE cells were clearly involved in the mineralisation of the cap enameloid at the mineralisation and maturation stages.

This review is concerned with the development of the rat corticospinal tract (CST). The CST is a long descending central pathway, restricted to mammals, which is involved both in motor and sensory control. The rat CST is a very useful model in experimental research on the development of fibre systems in mammals because of its postnatal outgrowth throughout the spinal cord as well as its experimental accessibility. Hence mechanisms underlying axon outgrowth and subsequent target cell finding can be studied relatively easily. In this respect the corticospinal tract forms an important example and model system for the better understanding of central nervous system development in general.

Alpha-fetoprotein (AFP) is the major serum protein during development. AFP is one of the earliest proteins to be synthesised by the embryonic liver. The synthesis of AFP decreases dramatically after birth and only trace amounts are expressed in the adult liver. The tissue distribution of AFP in early human embryogenesis has not been defined. We have studied the expression pattern of AFP mRNA in human and mouse embryos by in situ hybridisation. In humans, AFP is expressed in the hepatic diverticulum at 26 d postovulation as it differentiates from the foregut endoderm (i.e. in the most primitive hepatocytes). It is also expressed in the endoderm of the gastrointestinal tract and in the yolk sac at this age. AFP is subsequently expressed in the mesonephros and transiently in the developing pancreas. In the mouse, no expression of AFP was observed in the mesonephros but other sites of expression were similar. Thus AFP has a distinct temporospatial expression pattern during the embryonic period and this differs between human and mouse species. It is interesting that AFP is expressed by tumours such as primitive gastrointestinal, renal cell and pancreatic tumours as well as those of hepatocyte origin. This distribution reflects the sites of AFP expression during development.

The occurrence and distribution of neuropeptide-containing nerve fibres in the human circumvallate papillae were examined by the peroxidase–antiperoxidase immunolocalisation method using surgical specimens that had not been subjected to radiotherapy, and the abundance of neuropeptide-containing fibres was expressed as the percentage of total nerve fibres demonstrated by protein gene product (PGP) 9.5 immunoreactivity for a quantitative representation of these peptidergic fibres. Substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactive (IR) nerve fibres were densely distributed in the connective tissue core of the circumvallate papillae, and some SP and CGRP-IR fibres were associated with the taste buds. A moderate number of vasoactive intestinal polypeptide (VIP)-IR fibres and a few galanin (GAL)-IR fibres were also seen in the connective tissue core and subepithelial layer. There were, however, no VIP-IR or GAL-IR fibres associated with the taste buds. Neuropeptide Y (NPY)-IR fibres were few and were associated with the blood vessels. Within the epithelium of the circumvallate papillae, no peptidergic fibres were found, although a number of PGP 9.5-IR fibres were detected. The abundance of SP, CGRP, VIP, and GAL-IR fibres expressed as the percentage of total PGP 9.5 IR fibres was 25.35±3.45%, 22.18±3.26%, 10.23±1.18%, and 4.12±1.05%, respectively. The percentage of NPY-IR fibres was below 3%. In a deeper layer of the papillae, a few VIP, GAL, and NPY-IR ganglion cells were found, and VIP immunoreactivity was detected in a few cells of the taste buds. There was no somatostatin, leucine enkephalin, or methionine enkephalin immunoreactivity in the circumvallate papillae. These results suggest that the dense SP and CGRP-IR fibres within the connective tissue core of the human circumvallate papillae may be involved in the deep sensation of the tongue.

The streptozotocin (STZ)-diabetic rat, the most commonly employed model of experimental diabetic neuropathy, is characterised by a reduction in nerve conduction velocity, pain threshold and blood flow. Whether or not structural abnormalities underlie these functional abnormalities is unclear. 10 adult male Sprague–Dawley STZ-diabetic rats (diabetes duration 27 d) and 10 age-matched (23 wk) control animals were studied. Motor nerve conduction velocity (m s−1) was significantly reduced in diabetic (41.31±0.8) compared with control (46.15±1.5) animals (P<0.001). The concentration of sciatic nerve glucose (P<0.001), fructose (P<0.001) and sorbitol (P<0.001) was elevated, and myoinositol (P<0.001) was reduced in diabetic compared with control animals. Detailed morphometric studies demonstrated no significant difference in fascicular area, myelinated fibre density, fibre and axon areas as well as unmyelinated fibre density and diameter. Endoneurial capillary density, basement membrane area and endothelial cell profile number did not differ between diabetic and control animals. However, luminal area (P<0.03) was increased and endothelial cell area (P<0.08) was decreased in the diabetic rats. We conclude there is no detectable structural basis for the reduction in nerve conduction velocity, pain threshold or blood flow, observed in the streptozotocin diabetic rat.

The vocal ligaments insert at the anterior and posterior commissures of the larynx. These structures fulfil biomechanical functions, balancing the different elastic moduli of tendon, cartilage or bone and undergo age-related changes that may be responsible for voice changes with increasing age. The aim of this study was to analyse the insertion structures of the vocal ligaments by means of macroscopic, histological, immunohistochemical and electron-microscopic methods and to draw conclusions from age-related structural changes on a functional basis. Investigations were carried out on the larynges of 22 males and 15 females (aged 1–95 y). In adolescence, the insertion zone of the vocal ligament tendon, a dense network of connective tissue rich in sulphated glycosaminoglycans at the thyroid cartilage, is characterised by a layer between tendon and cartilage comparable to fibrocartilage. The insertion zone lacks a perichondrium. Collagen fibrils of the vocal ligament tendon penetrate directly into the thyroid cartilage. In the insertion area, the chondrocytes are surrounded by collagen fibrils, which show positive reactivity to antibodies against type I and type III collagen. Sulphated glycosaminoglycans are integrated between the collagen fibrils. In the area of the posterior glottis, elastic cartilage rests like a cap on the hyaline base of the arytenoid cartilage. There is no distinctive border between the structures. With increasing age, ossification of the laryngeal skeleton occurs, involving hyaline cartilage at the posterior glottis and hyaline and fibrocartilage at the anterior commissure. At the same time, a loss of sulphated glycosaminoglycans is observed inside the vocal ligament tendon. Advanced ossification of the laryngeal skeleton, particularly in the area of the commissures, an increasing loss of glycosaminoglycans in the vocal ligament tendon and changes in the elastic tissue reduce the elastic modulus between tendon, cartilage and bone, thus ‘stiffening’ the insertion zones, which could be one factor among others favouring voice changes with advancing age.

A 3-dimensional computerised system with landmark representation of the soft-tissue facial surface allows noninvasive and fast quantitative study of facial growth. The aims of the present investigation were (1) to provide reference data for selected dimensions of lips (linear distances and ratios, vermilion area, volume); (2) to quantify the relevant growth changes; and (3) to evaluate sex differences in growth patterns. The 3- dimensional coordinates of 6 soft-tissue landmarks on the lips were obtained by an optoelectronic instrument in a mixed longitudinal and cross-sectional study (2023 examinations in 1348 healthy subjects between 6 y of age and young adulthood). From the landmarks, several linear distances (mouth width, total vermilion height, total lip height, upper lip height), the vermilion height-to-mouth width ratio, some areas (vermilion of the upper lip, vermilion of the lower lip, total vermilion) and volumes (upper lip volume, lower lip volume, total lip volume) were calculated and averaged for age and sex. Male values were compared with female values by means of Student's t test. Within each age group all lip dimensions (distances, areas, volumes) were significantly larger in boys than in girls (P < 0.05), with some exceptions in the first age groups and coinciding with the earlier female growth spurt, whereas the vermilion height-to-mouth width ratio did not show a corresponding sexual dimorphism. Linear distances in girls had almost reached adult dimensions in the 13–14 y age group, while in boys a large increase was still to occur. The attainment of adult dimensions was faster in the upper than in the lower lip, especially in girls. The method used in the present investigation allowed the noninvasive evaluation of a large sample of nonpatient subjects, leading to the definition of 3-dimensional normative data. Data collected in the present study could represent a data base for the quantitative description of human lip morphology from childhood to young adulthood.