Metabolic pathways of the fossil dinosaur bones. Part V. Morphological differentiation of osteocyte lacunae and bone canaliculi and their significance in the system of extracellular communication

The study was carried out on dinosaur bones nearly 80 million years old. Samples for examination were prepared with specially elaborated methods. The light and transmission electron microscopic images permitted two kinds of bone lacunae and two types of paralacunar canalicular endings to be distinguished. The lacunae of the first kind were characterized by their elongated shape, their length exceeding their width several times, their dimensions being 31.2/9.4 microns. The lacunae of the other kind were not so long, their mean measurements amounting to 21.32/9.7 microns. Among the paralacunar canalicular endings those of small diameter were more numerous. The canaliculi of wider, funnel-shaped endings amounted to two or three, they were usually localized in the polar part of the lacuna, and were defined as the axial canaliculi. These were canaliculi of a large diameter. The canalicular wall was constructed of collagen fibres. The same fibres were found in the lacunar wall. Also a relationship between the structure of the lacunar wall and the localization of an osteocyte in the lacuna was analysed in the light and electron microscopes. In regard to the structure of the bone lacuna and the localization of an osteocyte in it, zones A and B were distinguished. Zone A had a characteristic loose and disorderly system of collagen fibres building the lacunar wall. The fibres in this area were by nature open to view. Besides, this region of the lacunar wall revealed specific terraced hollows. Zone B was distinguished by a compact system of parallelly arranged collagen fibres, which formed characteristic ridges in the lacunar wall. The localization of the osteocyte in the lacuna was irregular, the pericellular space around it being of variable width. This space was shown to contain mucopolysaccharides. The images obtained from dinosaur bone were compared with those already known for modern bone. These comparisons permitted it to be ascertained that zone A corresponds to a spot in the lacuna in which the osteocyte exhibits a decreased activity. Zone B is the area of the actual direction of the osteocyte's activity aiming at the shaping of the wall of its lacuna. It can be supposed that the widened endings of the paralacunar canaliculi perform more important functions in conveyance, this being evident from comparisons of analogous areas in modern bone.     

Studies of the fossil dinosaur bone in the scanning electron microscope.

A fossil dinosaur bone, 80 million years old, was subjected to investigation in the scanning microscope. The bone surfaces to be examined were prepared with appropritely modified methods used in the technique of replication in transmission electron microscopy. In the scanning microscope pictures of vascular canals were obtained. The walls of these canals were shown to be formed of collagen fibrils. Moreover, it was demonstrated that the internal surface of the canal wall is made up of bundles of collagen fibrils which run obliquely, corkscrewwise, and in the form of plexus to the long axis of tke canal; Besides, osteocytes of the dinosaur bone were isolated and pictures of their spatial structure together with characteristic points of departure of processes from the cell body were obtained.     

Bone canaliculus endings in the area of the osteocyte lacuna. Electron-microscopic studies.

Light- and electron-microscopic studies were carried out on the bone canaliculi and their endings in the wall fo the osteocyte lacuna. Two types of canalicular endings were distinguished in the lacuna wall. Those of the first type, fairly numerous, are the endings of small diameter, which do not branch off in the immediate proximity of the lacuna. The other type, occurring in twos or threes, are large in diameter and branch off in the close vicinity of the lacuna, invariably possessing two or three processes which run up to the point of branching of the canaliculus. The images obtained made it possible to demonstrate that the collagen fibrils in both types of endings in the lacuna wall are, in principle, arranged in a similar manner. Nonethless, the type of end formation found where the fibrils run along the axis of the lacuna differs from that for the fibrils in a plexus.     

Metabolic pathways of the fossil dinosaur bones. Part III. Intermediary and other osteocytes in the system of metabolic pathways of dinosaur bone

The fossil dinosaur bone material, 80 million years old was studied. Samples for analysis were prepared with specially elaborated methods. Images obtained in the light, transmission electron, and scanning electron microscopes revealed the spatial distribution of the osteocytes lying near and far from the vascular canal. Osteocytes of particular kind were found to be present in the immediate vicinity of the canal. The characteristic morphological structure and the localization of this osteocytes between the vascular canal and the osteocytes lying farther from the canal, as well as the mediation of this cell in the system of connections between those elements, served as a basis for the separation of this cells as the intermediary osteocyte. Among the osteocytes situated farther from the vascular canal, three kinds were distinguished: mono-, bi-, and multipolar, according to the kinds of processes and their distribution in relation to the mother cell body. By analogy with modern bone, in dinosaur bone specific functions may be ascribed to the distinguished types of osteocytes and to their differentiated processes in the conduction of nutrient and building elements and metabolites from the vascular canal to the intermediary osteocytes and, with their participation, to other osteocytes lying farther from the canal. This should naturally be analysed as the two-way tract.     

Forearm bone histology of the small theropod Daliansaurus liaoningensis (Paraves: Troodontidae) from the Yixian Formation,Liaoning, China

We present the first histological analysis of forelimb bones in a troodontid dinosaur, Daliansaurus liaoningensis, from the Early Cretaceous of China using osteohistological thin-sectioning and high-resolution synchrotron-based imaging. The thin wall compacta consists of primary bone, and three lines of arrested growth (LAG) in the radius (R) and two in the ulna (U) divide these into successive zones. Results show that the new fossil has four distinct bone depositional rates: (1) fastest deposition in inner zones R1 and U1 (fibro-lamellar bone with a plexiform-like vasculature); (2) slowed deposition in outer zones R1 and U1 + U2 (loss of vascular density and plexiform component); (3) fluctuating rates of deposition in zones R2 + R3 and in the inner zone U3 (alternating bands of circumferentially organised primary osteons and avascular bone); and (4) slowest deposition in zone R4 and the outer zone U3 (lamellar bone constituting the external fundamental system). Collectively, these growth characteristics suggest that the fossil is an individual that passed the exponential growth phase by the first year, and perished three years later. We conclude that the histology is consistent with an interpretation of this specimen as a late maturing individual that had not yet attained maximum somatic size.     

Ultrastructure of the kidney of the newt

In the newt [Triturus vulgaris (J.)] kidney a zone of single nephrons is distinguished, where there are ten nephrons, connected with the paramesonephral (Müller's) canal, and another zone of the renal mass; in the latter the main part of nephrons is situated, which are connected with the ureter by means of collecting tubules. In these zones of the kidney ultrastructure of epitheliocytes in the proximal and distal parts is different. The renal corpuscles of the epithelial cell in the cervical and in the intermediate parts are similar in both zones. In the zone of the single nephrons a specific peculiarity of epitheliocytes in the proximal and in the distal parts of the canaliculi is presence of numerous secretory granules in their cytoplasm. The canalicular epitheliocytes in the renal mass zone are different in the terminal and in the initial parts of the canaliculi: the former contains more mitochondria, and the area of the basolateral parts of plasmolemma is greater than those in the latter. These results are in accordance with the level of sodium ions transport in these parts of the canaliculus.     

Structure of the sensory innervation of the anal canal in the pig. A light- and electron-microscopical study

The sensory innervation of the anal canal of the pig was investigated by light and electron microscopy. The distribution of the different types of sensory nerve endings correlates with the histology of different zones: (1) After the rectal mucosa there was a zone lined with nonkeratinized stratified squamous epithelium. (2) A middle zone was lined with keratinized stratified squamous epithelium. Here the dermis already showed a papillary and reticular layer. (3) The last zone showed hairy skin with a high hair density. The following nerve endings were found: Free nerve endings reached the stratum superficiale in nonkeratinized squamous epithelium and the stratum granulosum in the keratinized squamous epithelium. Dermal free nerve endings were found in all zones near the epithelium and two different types were identified as those derived from C-fibers and those from A-delta-fibers. Merkel nerve endings showed different features depending on their location. Few Merkel-like cells were found in the epithelium of the anal crypts. Typical Merkel Tastscheiben were located at the base of epithelial ridges or pegs in zones 2 and 3. The number of Merkel cells varied up to 200. The myelinated afferent fiber supplied 10-15 Merkel cells. Merkel cells were also found regularly in the outermost layer of the external rooth sheath of hair follicles at about the same level as perifollicular nerve endings. Lamellated corpuscles were found in the dermis of all zones except the cranial part of zone 1, where the anal crypts are located. Generally they consisted of a central nerve terminal which may be branched. Each terminal was surrounded by an inner core of concentrically arranged lamellae of the terminal Schwann cell and one or several inner cores were included in a capsule of perineural cells. The size of the corpuscle, the regularity of the inner core and the number of capsular layers depended on the location of the corpuscle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Perivascular cells in cartilage canals of the developing mouse epiphysis

Morphological variability among perivascular cells adjacent to cartilage matrix during the elongation of canals through both uncalcified and calcified matrix has not been reported. Cartilage canals were located in distal femoral epiphyses of 5- to 7-day-old mice and identified as vascular channels arising from perichondrial surfaces along the condyles and intercondylar fossae. Three stages of canal development were identified based on the length of canals and on characteristics of chondrocytes and matrix surrounding the canals. Superficial canals terminated in uncalcified matrix of resting cartilage; intermediate canals terminated in matrix containing hypertrophic chondrocytes; deep canals terminated in calcified matrix. The ultrastructural morphology of perivascular cells in contact with the matrix varied in the three stages. Cells resembling fibroblasts and vacuolated macrophages were present adjacent to the uncalcified matrix in superficial canals. At the tips of intermediate canals, cells resembling fibroblasts were larger, contained numerous lysosomes and phagolysosomes, and were in intimate contact with the matrix. At the tips of deep canals, chondroclasts with ruffled borders and clear zones contacted the calcified matrix. The results indicate that 1) mouse epiphyses provide a suitable model for studying cartilage-canal perivascular cells, 2) calcification of cartilage matrix occurs along the course of the canal, and 3) the morphology of perivascular cells in contact with the matrix may be determined, in part, by matrix calcification.     

Electron microscope studies on the development of the external zone of the mouse median eminence

Summary The development of the external zone of the median eminence of the mouse was studied in the electron microscope. The examination follows the development of the embryo from the 15th day of the gestation period and the juvenile growth until 24 days of age.Single terminals of the tubero-infundibular neurons of the external zone were found to extend to the outer basement membrane of the perivascular space of the portal primary capillary plexus in the 16 day-old embryo. In the 18 day-old embryo a narrow external zone has developed. Organization of the external zone into the adult pattern is accomplished at the age of three to four weeks. Small agranular as well as large granular vesicles are present in the tubero-infundibular nerve terminals even in the 16 day-old embryo.Changes in the organization of the nerve endings along the outer perivascular basement membrane in relation to the ependymal vascular feet were considered.     

Ependymoneuronal specializations between LHRH fibers and cells of the cerebroventricular system

Summary Light-and electron-microscopic immunocytochemistry (LM-ICC and EM-ICC) were used to visualize luteinizing hormone-releasing hormone (LHRH) in fibres associated with ventricular ependyma and tanycytes of the median eminence. LM-ICC suggests that LHRH fibers appear to enter the third ventricle. However, with EM-ICC, LHRH fibers are in fact found within ependymal canaliculi formed by adjacent ependymal cells. The canaliculi contain other myelinated and unmyelinated axons in addition to immunoreactive LHRH fibers. Thin slips of ependymal and tanycyte processes project into the canaliculi and enclose axons to varying degrees. At the median eminence many LHRH fibers bend sharply downwards from their ventricular course and travel with tanycytic processes towards their common destination — the perivascular space of the hypophysial-portal vascular system. Here, EM-ICC reveals that LHRH fibers closely contact basal processes of tanycytes. Lateral processes from tanycytes form glioplasmic sheaths which surround some individual LHRH fibers. A few LHRH terminals contact the perivascular space directly but more often are separated from the perivascular space by intervening glia. It is hypothesized that: (1) glia of this region responds to the physiological state of the animal and may determine the degree of LHRH secretion by varying the extent of glial investment of LHRH terminals; and (2) may play a role during development by providing direction and support for LHRH fibers similar to that described for radial and other glial cells.     

Functional topography and ultrastructure of periarticular mechanoreceptors in the lateral elbow region of the rat

The distribution and ultrastructure of sensory nerve endings were investigated in the deep lateral elbow region of the rat. Three zones of distribution of mechanoreceptors were distinguished, each in relation to the functional architecture of the connective and muscular tissue in that area: (1) a zone with muscle spindles, Golgi tendon organs, free nerve endings and single small lamellated corpuscles ('muscle-tendon spectrum'), situated in the middle third of the supinator muscle and its superficial aponeurosis; (2) a zone with small lamellated corpuscles and free nerve endings, situated pericapsularly to the humeroradial joint capsule ('shearing spectrum'): this moderately dense, irregular connective tissue is covered by the proximal continuation of the supinator's aponeurosis, and muscle fibers insert from beneath this aponeurosis, which displays, as a part of the joint capsule, a strong collagenous tissue plate; (3) a zone with only free nerve endings within the tendon-like, most proximal part of the supinator's aponeurosis, inserting into the periosteal layer of the lateral humeral epicondyle ('endotenonial spectrum'): it is part of the joint capsule. The ultrastructure of these sensory endings is described and the distribution pattern of the mechanoreceptors observed is discussed in relation to the classification into 'muscle receptors' and 'joint receptors'.     

The Sensory Canal Systems of the Living Coelacanth, Latimeria Chalumnae: A New Instalment

Entire sensory canal systems of the coelacanth, Latimeria chalumnae, are described: not only the course of principal canals with their primary and secondary collaterals, but also the course and branches of the pit-line and reticular canals. The number of pores on the left side of the head were found to be 296 in an early (yolksac) embryo, 321 in a late term fetus, 485 in a juvenile, and 2974 in adults. This means that in latimeria most of the lateral-line canal system develop after parturition. Pit lines of the living coelacanth are not rows of superficial neuromasts but canals covered by a thin epidermis like in other sensory canals of the lateral line. These pit-line canals, however, have a very specific structure and branching pattern: the medial dorsal pit-line canal is connected by fine branches on top of the head. The infra-dentary pit-line canal connects via these branches with canals deep inside the bones. Several fine and richly branched canaliculi of unknown function radiate from each quadratojugal pit-line canal. The gular plate pit-line canal has superficially branching arms as well as connections to numerous deeper canals inside the bone. These canals consist of fine branches that in turn lead to and open on the ventral surface of the gular plates as small pores. The system is reminiscent of the reticular (pore) canal system known only from some fossil agnathans and fishes. Thus latimeria combines the reticular system of ancient vertebrates with the lateral-line system of modern fishes. The significance of this gular (possibly electro-sensory) system for feeding by the coelacanth will be discussed.     

Treatment of craniomaxillofacial fibrous dysplasia: how early and how extensive?

Twenty-eight craniomaxillofacial fibrous dysplasia patients were treated as early as the symptoms occurred. The principles of surgical treatment were based on the zones of involvement: total excision of dysplastic bone of fronto-orbital, zygoma, and upper maxillary origin (zone 1) and bone reconstruction primarily; conservative excision on hair-bearing skull (zone 2), central cranial base (zone 3), and tooth-bearing bones (zone 4); and optic canal decompression on patients with orbital dysplasia and decreasing visual acuity. Patients were followed for 1 to 11 years (average 5.3 years). No recurrence or invasion of the fibrous dysplasia into the grafted bone was seen. One patient had orthognathic maxillary osteotomy on the reconstructed maxilla 6 years after initial reconstruction. Five of 19 patients with alveolar dysplasia had a recurrence and were reshaped. One patient had mandibular sagittal osteotomies to set back the prognathic, fibrous dysplasic mandible after three attempts at conservative shaving. Another patient with mandibular fibrous dysplasia had recurrence with pain and a hemimandibulectomy with successful immediate free vascularized iliac bone graft reconstruction.     

ELECTRON MICROSCOPY OF THE OXYNTIC CELL IN THE GASTRIC GLANDS OF THE BULLFROG (RANA CATESBIANA) : I. The Non-Acid-Secreting Gastric Mucosa

The fine structure of the oxyntic cell from the gastric glands of the bullfrog was studied in lead hydroxide—stained sections of gastric mucosa fixed in buffered osmium tetroxide and embedded in n-butyl methacrylate. The oxyntic cell in non-acid-secreting stomachs (gastric juice pH, 7.4–7.8) is characterized by: (a) numerous closely packed smooth surfaced vesicular and tubular profiles disposed randomly in the cell; some of these elements show interconnections making it possible to identify this component with smooth surfaced endoplasmic reticula of certain other cell types, (b) a small percentage of rough surfaced profiles characteristic of endoplasmic reticula possessing RNP particles on the outer membrane surfaces, (c) a Golgi complex consisting of multiple isolated non-polarized arrays of smooth surfaced parallel elongated profiles and associated vesicular elements, (d) a sparse granular component (140 A) scattered freely in the cytoplasmic matrix, (e) numerous mitochondria with a dense matrix and containing an unusually large number of closely approximated cristae, (f) a number of zymogen granules consisting of either a dense body limited by a membrane or surrounded by a halo of less dense material which is in turn limited by a membrane, and (g) a number of granules (~260 A) containing several smaller granules (~80 A) identified presumably as glycogen. Intracellular canaliculi were not observed. Instead the free surface of the oxyntic cell facing the lumen of the gastric gland shows a complicated plication of the plasma membrane. Intercellular canaliculi are seen frequently between adjacent oxyntic cells. The walls of these canaliculi are made up of folded and ruffled cell membranes. The basal surface of the cell also exhibited this type of configuration. Occasional smooth surfaced profiles are seen communicating with the free surface, the wall of an intercellular canaliculus, or the basal surface of the cell. Although nerve endings were not found in association with oxyntic cells, unmyelinated nerves were observed in the vicinity of the gastric glands.     

On the fine structure of the perivascular cells in the neural lobe of rats

Summary The purpose of this study is to investigate the ultrastructural features of perivascular cells as found in the neural lobe of the hypophysis. In particular, an inquiry was made into the nature of the relationship of such cells to neurosecretory fibers and endings. The latter, in fact, are often invaginated within the perivascular cells and enveloped by their processes; furthermore, they often reveal a certain number of empty granules as well as characteristics of degenerative nature. In the course of this study the localization of the perivascular cells has been investigated as well as that of their processes within the extensive interlobular network typical of the hypophysial neural lobe of rodents. Based on the data gathered, the hypothesis is put forward that the perivascular cells play an important role in the turnover of neurosecretory endings, both under physiological and experimental conditions, contributing thereby to the release of post-hypophysial hormones.With the technical assistance of Vincenzo Panetta.     

Morphology of the teleost ampullary organs in marine salmontail catfish Neoarius graeffei (Pisces: Ariidae) with comparative analysis to freshwater and estuarine conspecifics

We hypothesized that due to the relative conductivity of the environment, and to maintain sensory function, ampullary organs of marine Neoarius graeffei would differ morphologically from those described previously for estuarine and freshwater conspecifics. Unlike the ampullary systems of N. graeffei from freshwater and estuarine habitats, the ampullary pores of marine specimens occur in two distinct patterns; numerous pores seemingly randomly scattered on the head and ventro‐lateral regions of the body, and pores arranged in distinctive vertical lines above the lateral line on the dorso‐lateral body of the fish. Light and electron microscopy revealed that the ampullary organs also differed morphologically from estuarine and freshwater specimens in the presence of longer ampullary canals, a hitherto unreported canal wall composition, and in the collagen sheath surrounding both the canal and the ampulla proper within dermal connective tissues. Ampullary pores were wider in marine individuals and opened to the longest ampullary canals reported for this species. The canal wall was lined by cuboidal and squamous epithelial cells. Each ampullary canal opened into a single ampulla proper containing significantly more receptor cells than estuarine and freshwater conspecifics. The distribution of ampullary pores as well as the microstructure of the ampullary organs indicates that the electrosensory system of marine N. graeffei differs from those of estuarine and freshwater specimens in ways that would be expected to maintain the functionality of the system in a highly conductive, fully marine environment, and reveals the remarkable plasticity of this species’ ampullary system in response to habitat conductivity. J. Morphol. 276:1047–1054, 2015. © 2015 Wiley Periodicals, Inc.     

Dopamine Receptors in the Human Dura Mater

Dopamine receptors (Dar) were studied as a component of the nervous dopaminergic system in the human dura mater. Dar were stained in several dural zones (vascular, perivascular, intervascular) in different regions (basal, calvarial, tentorial, occipital, frontal, parietal, temporal) of the cranial meninges. Specimens of human dura mater were harvested from autopsies of 10 elderly male subjects (age range, 60-75 years). Dar were labeled with specific (H3) markers, studied with radiobinding techniques (including liquid scintillation), stained for light microscope autoradiography, and measured by means of quantitative analysis of images. All results were evaluated with statistical analysis to identify significant results. More dural Dar were found in the basal region than in the calvarial one. Moreover, Dar are more abundant in the vascular and perivascular dural zone than in the intervascular one. The vascular distribution of Dar seemed to indicate that Dar play a role in the control of meningeal blood vessels. The location and distribution of D1 and D2 receptors in the human cranial dura mater confirmed the presence of a dopaminergic system, which could play an important role in controlling blood flow and/or other functions of meningeal membranes.     

Stromal cells of the bone marrow in growing bone

By means of electron microscopy, cytochemistry and radioautography with 3H-thymidine, the bone marrow stromal cells have been studied in the zones of endochondral osteogenesis in the rabbit and rat femoral bones. In the stromal cells demonstrating a high alkaline phosphatase activity are distinguished: perivascular, reticular fibroblastic, osteogenic cells. Populations of the perivascular phosphatase-positive cells include poorly differentiated DNA-synthesizing forms, as well as cells with signs of differentiation into stromal fibroblasts. Cleft-like spaces in cytoplasm of the fibroblastic reticular cells are, probably, formed as a result of lymphocyte-like mononuclears passing through. Phagocyting stromal elements are presented by macrophages, having perivascular localization and including into composition of erythroblastic islets. Mononuclear macrophages are revealed also on the surface of osseous trabecules, where they participate in destruction of hemopoetic and osteogenic cells.     

Cell population dynamics of periodontal ligament stimulated with parathyroid extract.

Young adult rats were injected with parathyroid extract (PTE). Periodontal ligament (PDL) adjacent to a previously resorbing alveolar bone surface was divided into four zones number I to IV, from bone to cementum. Zones I and IV were within 25 mmu of the bone and cementum surfaces, respectively, while a line bisecting the center of the PDL separated Zones II and III. A net increase of about 16 total nuclei in all zones was observed during the first five hours after PTE administration. Since local mitosis accounted for no more than two nuclei, approximately 14 cells apparently migrated into the area. Over the first five hours Zones I and II combined showed a 21-cell increase, being apparently the sole recipients of cells migrating into the field (14) plus approximately seven more from Zone III, which lost cells during the time period. The concurrent histological observation in Zone II, of increased intravascular monocytes and perivascular macrophages during the first five hours, suggests cells are migrating into Zone II via vascular channels. The data suggest two sources for increased PDL cellularity associated with stimulated osteoclast histogenesis: (1) local PDL cellular proliferation and (2) influx of migrating cells (probably through vascular channels) during first five hours after PTE.     

Potentialities of temporal bone computed tomography in the study of the facial nerve and in the diagnosis of peripheral pareses of thr 7th pair of cranial nerves

Computed tomography (CT) was used to examine 200 patients (400 temporal bones) aged 3 to 74 years who had no signs of facial nerve lesion and 28 patients who had clinical manifestations of peripheral paresis of the facial nerve of varying genesis. Multipositional CT of the temporal bone is the most informative mode of visualization of the fallopian canal which is embodied on tomographic scans in 100% of cases irrespective of the age of a patient. CT data indicate that the formation of the facial nerve canal brings to completion by the age of 6 years. The following causes of n. facialis paresis were identified: facial neuroma; sarcoma of the temporal bone sarcoma; dehiscence of the canal wall in otitis media acuta; destruction of the tympanic wall of the canal in otitis nedia chronica, fractures of the temporal bone, anomalies of the fallopian canal in temporal bone malformations; stenosis of the canal in fibrous dysplasia. The detected alterations of the n. facialis canal permits further policy of management of a patient to be defined.