Showing papers in "Journal of Anatomy in 1985"

Collagen orientations in the meniscus of the knee joint.

Abstract: X-ray diffraction shows that the collagen fibrils of dog, pig and human meniscus tend to be oriented circumferentially in the bulk tissue and radially in the surface region. Individual fibrils are not all oriented in these directions but are distributed about the preferred orientations with a standard deviation of around 15 degrees in the bulk tissue. Polarised light microscopy yields results which are consistent with X-ray diffraction. This technique also shows that the fibrils are aggregated into crimped fibres, resembling those of tendon, and that some of these fibres pass from the outer region of the meniscus into the bulk tissue. Artificial split lines demonstrate the radial orientation of outer fibres over most of the superior and inferior surfaces of the meniscus. Split lines reorient as they pass into the bulk tissue which is consistent with the interpretation of X-ray diffraction and polarised light microscopy results of this study. The pattern of collagen orientations is also consistent with the meniscus transmitting compressive load in the knee joint.

The fibre type composition of thoracic and lumbar paravertebral muscles in man.

Abstract: Samples of longissimus and multifidi muscles at the thoracic and lumbar levels of the spine were examined histochemically on autopsy specimens from 21 adult male subjects (aged 22 to 46 years) and on biopsies from 17 adult patients during surgery for disorders of the lumbar intervertebral disc. In the superficial and deep thoracic muscles, 74% of fibres were of the Type I variety. In the lumbar region, Type I fibres amounted to 57% in the superficial, and to 63% in the deep muscles. The diameter of Type I fibres was significantly greater than that of Type II fibres.

Connections of the hyperstriatum ventrale of the domestic chick (Gallus domesticus).

Abstract: The intermediate part of the medial component of the hyperstriatum ventrale (IMHV) of the chick telencephalon is implicated in the learning process of imprinting. The afferent connections of this region were investigated using the retrograde neuronal tracers horseradish peroxidase (HRP), nuclear yellow and fast blue. Labelled cells were found (i) ipsilaterally in the visual Wulst, neostriatum pars intermedia and caudalis, the posterior part of the hyperstriatum ventrale, the dorsal part of the archistriatum, paleostriatum augmentatum, dorsomedial part of the thalamus, and (ii) bilaterally in the hippocampus, area septalis, ventromedial part of the thalamus and the stratum album centrale of the tectum opticum. The efferent projections of the IMHV were studied using the anterograde tracer, [3H]leucine. Labelling was seen ipsilaterally over the dorsolateral part of the hemispherium telencephali, the paleostriatum augmentatum and the posterior and dorsal parts of the archistriatum. Double labelling with nuclear yellow and fast blue revealed (i) neurons in the IMHV which project to both the paleostriatum augmentatum and the archistriatum, and (ii) neurons in the hippocampus which project bilaterally to the IMHV.

The topographical anatomy of the lumbar epidural space.

Abstract: Although clinically important, the lumbar epidural space is inconsistently described in textbooks of both anatomy and anaesthetics. This anatomical study of twelve cadavers was performed in an attempt to clarify the description of this region. The dura mater, which possesses a midline fold in a very few cases, is apposed to the walls of the vertebral canal, and attached to them by connective tissue, which is sufficient to allow for displacement of the dural sac during movement of the spine and venous engorgement. Between the dura mater and the vertebral canal is a thin layer of areolar tissue. This contains the internal vertebral venous plexus and a posterior deposit of fat which lies in a recess between the ligamenta flava. These findings are discussed in relation to previous studies in an attempt to arrive at a cohesive description of the epidural region.

Failure to demonstrate sexual dimorphism of the corpus callosum in childhood.

Abstract: A quantitative and morphological study was made of the corpus callosum in children to assess possible sex differences. The shape of the splenium of the corpus callosum was observed to vary between bulbous and cylindrical types with respect to the body of the callosum. The variation was not gender-specific and covariate analyses taking account of brain weight and age detected no differences in splenial width or area between males and females in childhood. This is in contrast to the situation reported in adults.

Sagittal evaluation of elemental geometrical dimensions of human vertebrae.

Abstract: Geometrical configuration and dimensions of the human vertebra were investigated using radiographs of 157 normal healthy adult men. Measurements were based on five bony reference points, which can be defined in radiographs. The measurements permit the determination of nine dimensions that can be used for anthropometrical evaluation of the cervical and lumbar vertebrae. A simplified model of the vertebra in the sagittal plane is presented and serves as a basis for the geometrical measurements. In the cervical region, average width exceeded average height of vertebral bodies C3 to C7, while in C2 the average width was smaller than the average height; C7 was the longest and C3 the shortest cervical vertebra. In the lumbar region, average width exceeded average height of the vertebral bodies. Values for width and height did not differ significantly from L1 to L5; L3 was the longest and L5 the shortest lumbar vertebra.

The organisation of the efferent projections of the zona incerta.

Abstract: The hypothesis that the six cytoarchitectonically distinct subdivisions of the zona incerta send efferent projections to different parts of the brain was tested using retrograde fluorescent tracing techniques. Injections of tracer in the superior colliculus, pontomesencephalic tegmentum, thalamus or spinal cord resulted in characteristic and distinctive patterns of labelling in the zona incerta, suggesting that the different subdivisions of the zona incerta give rise to different sets of efferent projections. Thus, injections into the deep layers of the superior colliculus resulted in retrogradely labelled neurons predominantly in the zona incerta pars ventralis, whereas injections into the pontomesencephalic tegmentum, avoiding the superior colliculus, labelled neurons mostly in the zona incerta pars dorsalis. Parafascicular thalamic injections resulted in labelled neurons in the zona incerta pars rostropolaris, pars dorsalis, pars caudalis and a few in the pars ventralis. The spinal cord injections labelled predominantly the magnocellular cells of the zona incerta. The results of the double labelling experiment also give support to the conclusion that different areas of the zona incerta give rise to largely individual sets of efferent projections. Combined injections of tracers into the superior colliculus and thalamus resulted in the labelling of two essentially independent cell groups, the tectal projecting cells being found mainly in the zona incerta pars ventralis and the thalamic projecting cells being found in the zona incerta pars rostropolaris, pars dorsalis and pars caudalis. However, a small number of double labelled cells was found. These cells, which presumably send collateral projections to both the tectum and the thalamus, were found mainly in the dorsal part of the zona incerta pars ventralis, immediately next to the pars dorsalis. In the light of these findings it would appear that the zona incerta may be organised into largely distinct subdivisions, each of which has its own set of cytoarchitectonic and efferent projection characteristics.

The blood supply of the periosteum.

Abstract: Twelve goat limbs were injected with red latex and then carefully dissected to display the vessels of the periosteum. The blood supply of periosteum was found to be derived from four sets of vessels: (1) Intrinsic periosteal system. (2) Musculoperiosteal system. (3) Fascioperiosteal system. (4) Cortical capillary anastomoses. The intrinsic system of vessels lay within the fibrous layer of the periosteum. According to the pattern of these vessels they could be divided into: (a) a short vessel pattern, where there were many small vessels with no predominant direction; (b) a circular pattern, where the vessels encircled the bone; (c) a longitudinal pattern, where the vessels ran parallel to the long axis of the bone. The musculoperiosteal system consisted of connections between the muscle circulation and the periosteal vessels at the sites of muscle origin. The fascioperiosteal system consisted of branches from a limb artery that ran in a fascial plane between muscles to supply the periosteum. The cortical capillary anastomosis consisted of capillaries that ran in the bone cortex between the intramedullary circulation and the periosteal vessels.

Crypts, villi and microvilli in the small intestine of the rat. A stereological study of their variability within and between animals.

Abstract: Small intestines from normal adult rats were quantified by optical and electron microscopy using stereological principles devised for the purpose. Five segments per bowel were examined. Baseline data characterising villi, microvilli and crypts of Lieberkuhn were used to study differences between segments and between animals. Intestines fixed by in situ perfusion had, on average, 100 cm2 of primary mucosa. This basic surface was amplified to 500 cm2 by villi and to 1 m2 by the microvilli of enterocytes. Villous and microvillous surface areas may scale to body weight in the same way as metabolic requirements. Proximodistal gradients in mucosal architecture existed for the volumes and surface areas of villi and for the numbers, lengths, diameters and surface areas of microvilli. Most variables were higher proximally and declined towards the terminal ileum. The volume of crypts stayed constant throughout the entire intestine and ratios between villous dimensions (volumes and surface areas) and crypt volume did not vary between animals. Findings are discussed in the context of regional differences in bowel function and of their relevance to studies of epithelial kinetics.

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The Harderian gland its secretory duct and porphyrin content in the Plains mouse (Pseudomys australis)

Abstract: The Harderian gland of the Australian Plains mouse (Pseudomys australis) consists of tubules lined by a single layer of epithelial cells with a surrounding meshwork of myoepithelial cells. The epithelium contains three types of cell. Type I cells, characterised by their many large apical lipid vacuoles, are comparable with cells reported in other rodents. Secretion is exocytotic and, to a lesser extent, apocrine. Type II cells are highly distinctive with extremely large mitochondria arranged in stacks and whorls. Unusually for Harderian glands, these cells possess prominent conventional Golgi complexes and lysosomes. Cytoplasmic 'slashes', possible vacuole-precursors, are also present. Type III cells have few distinguishing features and may be resting cells. They are occasionally binucleate and mitotic figures occur. The gland contains stored porphyrins, chiefly protoporphyrin, in the form of solid intraluminal accretions. There is a marked sex difference, with females having higher levels of porphyrin than males. Among the components of the interstitial tissue are mast cells, plasma cells and porphyrin-containing macrophages. The secretory duct contains large quantities of cell debris, including nuclei, and is lined by columnar cells with single large apical vacuoles. The outer opening of the duct is lined by mucus-secreting cells and stratified squamous epithelium.

Axonal and vascular changes following injury to the rat's optic nerve.

Abstract: The optic nerve of the rat has been examined by light and electron microscopy, and also for vascular permeability to fluorescently labelled albumin, 2 days to 34 weeks after crushing in the orbit. The operation was usually followed by loss of 20-70% of the retinal ganglion cells. Axons could be followed from the retina into the optic nerve at all postoperative times, but they always ended anterior to the lesion. Evidence of feeble regenerative growth of optic axons was seen in the first few postoperative weeks: bifurcating fibres and fibres that turned back towards the eye were present within the optic nerve anterior to the lesion. At the site of crushing, the optic nerve eventually became a thin cord of astroglia, surrounded and partly infiltrated by collagenous connective tissue. Long argyrophilic fibres were conspicuous in the intracranial part of the crushed optic nerve from the seventh to the fourteenth postoperative week. These were shown by electron microscopy to be degenerating myelinated axons that had not been phagocytosed. It was conceivable that axons from the contralateral retina could have sprouted at the chiasma and grown into the degenerated optic nerve. This possibility was excluded by tracing anterograde axonal transport of horseradish peroxidase injected into the contralateral eye. Intravenously injected fluorescent protein entered the connective tissue of the orbit and the connective tissue trabeculae of the optic nerve, but it did not permeate into the central nervous tissue except at the lamina cribrosa, where the optic axons pierce the sclera. Permeability at this site was the same on the operated and unoperated sides. Abnormal permeability of the vasculature was seen at the site of crushing the optic nerve. Fluorescence there was strongest in the first two postoperative weeks and was not seen after the third week. A much less conspicuous defect of barrier function occurred in the intracranial portion of the crushed optic nerve, from the seventh to the fourteenth postoperative week. The responses of the optic nerve of the rat to axotomy contrast markedly with those of the goldfish, in which the blood vessels become permeable to protein throughout the optic pathway and the axons regenerate successfully. Various attempts were made to increase or prolong the opening of the blood-optic nerve barrier in the rat, in the hope of enhancing axonal regeneration, but these endeavours were all unsuccessful.

Quantitative distribution of enteroendocrine cells in the gastrointestinal tract of the adult opossum, Didelphis virginiana

Abstract: The distribution and quantification of enteroendocrine cells exhibiting immunoreactivities to nine peptides and one amine were examined in the gastrointestinal mucosa of the adult opossum using specific immunocytochemical methods. In the stomach, 90% of the enteroendocrine cells are confined to the pyloric glands and this region contained 73% of the gastrin-containing cells, 60% of the somatostatin-containing cells and 9% of cells reactive for 5-HT. Enteroendocrine cells showing immunoreactivities to glucagon, pancreatic polypeptide, somatostatin and 5-HT were observed scattered within the oxyntic glands. Only somatostatin and 5-HT positive cells were found in the cardiac glands. Immunoreactivities to CCK, glucagon, gastrin, BPP, somatostatin, secretin, motilin, neurotensin, GIP and 5-HT were observed in the epithelium of the small intestine. Although considerable variation exists in the distribution of individual enteroendocrine cell types along the intestinal tract, nearly equal numbers of enteroendocrine cells were observed in each segment. The percentage of enteroendocrine cells increases distally in the colon. Of the three enteroendocrine cell types present, somatostatin- and 5-HT-immunoreactive cells are evenly distributed, whereas neurotensin-immunoreactive cells increase in numbers distally, resulting in an increase in total number.

Neuropeptide localisation in the substantia innominata and adjacent regions of the human brain.

Abstract: A dense peptidergic innervation has been demonstrated in the substantia innominata region in postmortem specimens of human brain using immunocytochemical techniques. A peptidergic innervation of the nucleus of Meynert - the prominent nucleus of this area containing the cholinergic cell bodies which innervate the cerebral cortex - has been demonstrated by immunostaining with antisera against the following eight neuropeptides: somatostatin, substance P, cholecystokinin octapeptide, vasoactive intestinal polypeptide, met-enkephalin, ACTH, alpha-MSH and oxytocin. Other immunocytochemical features of the substantia innominata region include a dense band of peptide immunoreactivity beneath the medial aspect of the anterior commissure and islands of somatostatin and substance P terminal immunoreactivity in the rostral part of the substantia innominata. Somatostatin immunostained cell bodies have been located in a discrete area of the bed nucleus of the stria terminalis and in the rostral portion of the substantia innominata, nucleus accumbens and the ventral part of the putamen. The dense band of peptide immunoreactivity beneath the medial aspect of the anterior commissure consists of ribbon-like processes stained with antisera against somatostatin, substance P, cholecystokinin octapeptide, vasoactive intestinal polypeptide and met-enkephalin. Less intense immunostaining of ribbon-like elements is also present in the globus pallidus. The presence of a peptidergic innervation to the nucleus of Meynert suggests a possible important modulatory role in cortical cholinergic function.

The histogenesis of the gonad in rat embryos.

Abstract: Gonadogenesis was investigated using Wistar rat embryos at 12-14 days after fertilisation. In indifferent gonads, a mesonephric tubule which bifurcates from the mesonephric duct at the upper end of the gonadal anlage ramifies into six to eight branches, the distal portions of which are contiguous, in contact with, or in close proximity to, the coelomic epithelium of the gonadal ridge. After the primordial germ cells reach the gonadal ridge, the overlying epithelium proliferates and clear cells appear in the distal portion of each mesonephric tubule, proliferating and forming cord-like structures. The primordial germ cells appear to enter these cell cords by an amoeboid type of movement. The basal lamina covering the cell cord partially disappears near the germ cells. The germ cells within the cord migrate toward the proximal portion of the cell cord and proliferate in great profusion. From the present observations, it can be concluded that the gonad is mainly formed of clear cell cords originating in mesonephric tubules into which germ cells have entered. The original mesenchymal cells and blood vessels form the interstitial tissue of the gonad. The rete testis and rete ovarii are of mesonephric tubule origin.

Studies on the distribution of binucleate cells in the placenta of the sheep with a monoclonal antibody SBU-3.

Abstract: The distribution of cells recognised by the monoclonal antibody SBU-3 raised against trophoblast microvilli during development of the sheep placenta was investigated using the indirect immunoperoxidase technique. At 21 days of gestation, the placental antigen recognised by the monoclonal antibody SBU-3 was observed in the binucleate cells in the trophoblast located in close apposition to the caruncular epithelium. From 30-100 days there was a dramatic increase in the number of SBU-3-positive cells in the placentomal trophoblast and the syncytial layer in the placentome. An insignificant number of SBU-3-positive cells was observed in the interplacentomal trophoblast. By 120-145 days, the syncytial layer became less intensely stained, but strongly SBU-3-positive binucleate cells were still present in the placentomal trophoblast. It is concluded that the antigen recognised by the monoclonal antibody SBU-3 is a secretory product of the binucleate cells of the trophoblast, whose function is at present unknown. The findings in this study are consistent with the theory that the syncytium is formed by fusion of migrating fetal binucleate cells.

The functional morphology of the superior articular processes of the lumbar vertebrae

Abstract: The bony trabeculae in the superior articular processes of the lumbar vertebrae form a series of overlapping pointed arches that correspond to the lines of stress produced during rotation. By using a photoelastic model, it has been possible to demonstrate that this structural arrangement is a functional adaptation to alternate lateral and medial bending movements. The functional significance of the articular processes is obviously to limit rotation, which can take place in the lumbar segment of the vertebral column during any asymmetrical movement of the body. The alternate bending movements of the superior articular processes arise partly from the laterally directed pressure of the corresponding inferior process, and partly from the medially directed pull of the firm 'transverse strengthening ligaments' of the joint capsule.

Changes in myelin sheath thickness and internode geometry in the rabbit phrenic nerve during growth.

Abstract: The rabbit phrenic nerve was studied at seven phases of growth from the newborn to the adult to determine the length of the nerve fibres, the length of the internodes, the fibre calibre, the geometric proportions of the internodes and the thickness of the myelin sheaths. The elongation of the internodes corresponded precisely to the elongation of the nerve, indicating a constant number of approximately 140 internodes per fibre, each internode elongating commensurate with body growth. Internode elongation was accompanied by increases in fibre calibre, but these parameters did not change in precise proportion. The internodes of thick fibres were relatively short for calibre, as defined by the length/diameter quotient. This trend of foreshortening changed during growth. Sheath thickness, defined by the quotient axon diameter/fibre diameter, was determined with a computer-assisted method. Fibres of young rabbits had relatively thin sheaths for axon calibre, compared with adult rabbits. The changes in sheath thickness corresponded to the changes in internode geometry. This was consistent with previous studies showing that elongation or foreshortening of an internode of a given calibre has a slight, but definite effect on the thickness of its myelin sheath.

The stabilising function of the mm. iliocostales and the mm. multifidi during walking.

Abstract: The myoelectric activity of the mm. multifidi and the mm. iliocostales lumborum of six subjects was recorded during walking. The subjects walked on a treadmill as well as on a fixed walkway. On the treadmill, recordings were made at two different speeds and with a varying loading of the spine. There was almost no difference in myoelectric activity time between the treadmill and the fixed walkway. Related to unloaded walking, both the multifidi and the iliocostales showed an increase in activity time when the subjects carried a load of 5 kg in front of the trunk and a decrease of activity time with a load of 5 kg on the back. A load on the lateral aspect of the body shortened the muscle activity time of the multifidi on the homolateral side. In three subjects the same pattern was found for the iliocostales, but in the other three subjects there was no activity registered at all. On the side contralateral to the load, the multifidi showed no increase of activity time while the iliocostales muscles demonstrated an increase. It is concluded that during walking the iliocostalis muscle has a more important function in lateral bending than the multifidus. It was remarkable that the multifidi muscles of the left side were active for longer periods than were those of the right side in all situations except during lateral loading.