Serial Transverse Sections Research Articles

Visualization of cardiac muscle thin filaments and measurement of their lengths by electron tomography

AimsAn intriguing difference between vertebrate skeletal and cardiac muscles is that the lengths of the thin filaments are constant in the former but variable in the latter. The thick filaments have constant lengths in both types of muscles. The contractile behaviour of a muscle is affected by the lengths of both types of filaments as the tension generated during contraction depends on the amount of filament overlap. To understand the behaviour of cardiac muscle, it is important to know the distribution of the thin filament lengths. The previous detailed analysis by Robinson and Winegrad used serial transverse sections to determine the lengths of the thin filaments. However, the precision, set by the 100 nm section thickness, was low. Here, we have used electron tomography to produce 3D images of rat and mouse cardiac muscles in which we can actually see individual thin filaments up to the free ends and see that these free ends have variable locations. For comparison, we also measure the thin filament lengths in skeletal muscle (frog sartorius).Methods and resultsCardiac papillary muscles were obtained from a rat (Sprague–Dawley) and a mouse (C57/B6). Skeletal muscle (sartorius) was obtained from a frog (Rana pipiens). Longitudinal sections (100 nm thick) were used to produce tilt series and tomograms from which the thin filament paths were traced. Cardiac papillary muscle thin filaments in rat and mouse range from 0.94 to 1.10 µm, with a mean length of 1.04 µm and standard deviation of 0.03 µm. For frog sartorius muscle, the thin filament length was 0.94 µm with standard deviation of 0.01 µm.ConclusionElectron tomography of cardiac and skeletal muscles allows direct visualization and high precision measurement of the lengths of thin filaments.

Rachis of the genus Paspalum L. (Poaceae: Panicoideae: Paniceae): Anatomy and taxonomic significance of the primary branches of the inflorescences

Infrageneric classification of Paspalum is mainly based on characters of the inflorescence and spikelets. Some of the inflorescence characters usually used are the width and external morphology of the rachises of the racemes. Nevertheless, morphological terminology used in the literature is frequently imprecise. We examine the internal structure of the rachises of the racemes in Paspalum to: (a) compare it with the anatomy of a vegetative culm, (b) precisely describe its variation within the genus to search for features that could be used in taxonomy or phylogeny. Species representative of all subgenera and informal groups were studied. Serial transversal sections were made and analyzed using light microscopy. Many distinctive characters from the central keel and lateral wings allow to distinguish six anatomical types of rachises: Type I is the most frequent in the genus, being present in species of all subgenera; Type II characterizes Conjugata, Dissecta and Disticha groups; Type III is exclusive of subgenus Harpostachys; Type IV is common in Ceresia subgenus and it is also present in two species of Gardneriana group and in Paspalum guttatum of Erinatha group; Type V is present in Bonplandiana and Racemosa groups, and Type VI is exclusive of Paspalum falcatum of Falcata group. Rachises of the racemes are undoubtedly caulinar structures although many species present flat rachises, with vascular bundles arranged in one only row and with abundant photosynthetic tissues. This study permits to differentiate, by means of anatomical characters, rachises that are morphologically similar or undistinguishable. Some anatomical types of rachises are related to taxonomic groups or subgenera, stressing their taxonomic value. Using anatomical characters of the rachis of the Paspalum raceme can improve phylogenetic analyses.

Ovariectomy Delays Alveolar Wound Healing After Molar Extractions in Rats

This study was conducted to investigate the morphological effects of the absence of estrogen on alveolar wound healing of young female rats after tooth extraction. A total of 60 4- to 6-week-old female rats underwent bilateral ovariectomy (OVX) or sham operations. Three weeks later, the first mandibular molars were extracted. Subsequently, the animals were killed by cervical dislocation 3, 5, 7, 14, 21, or 28 days after tooth extraction. The mandibles were removed, and serial transversal sections of mesial alveolus of the first mandibular molars were obtained for histometric analysis. OVX sockets showed significant increases in fibroblasts and collagen content 3 and 5 days after the extractions, followed by significant decreases in these parameters in the subsequent periods. In accordance with the decreased collagen content in the latest period of healing, new bone formation was significantly reduced in the OVX animals. These findings suggest that the initial molecular changes observed in the absence of estrogen lead to delayed alveolar wound healing.

Adriamycin produces a reproducible teratogenic model of vertebral, anal, cardiovascular, tracheal, esophageal, renal, and limb anomalies in the mouse

Background/Purpose The Adriamycin rat model is an established model for vertebral, anal, cardiac, tracheal, esophageal, renal, and limb (VACTERL) anomalies and gastrointestinal atresias. Mice are the foremost mammal studied by developmental biologists, providing greater availability of molecular probes, antibodies, and transferable knowledge with transgenic studies. Only tracheoesophageal malformations have been previously described in the Adriamycin mouse model. The aim of this study was to carry out a dose-response analysis of the teratogenicity of Adriamycin in the mouse to determine the effect of the dose and timing of exposure in producing tracheoesophageal malformations and show if it causes other VACTERL anomalies. Methods CBA/Ca mice were accurately time mated (n = 30). Four different doses (0 [saline], 4, 5, and 6 mg/kg) of Adriamycin (EBEWE Pharma Ges.m.b.H. Nfg.KG, A-4866 Unterach, Austria) at 3 different timings of injections were compared. Dams received 2 intraperitoneal injections, 24 hours apart, commencing on day 7, 7.5, or 8. Fetuses were harvested on day 18. Anomalies were examined using a dissecting microscope and serial transverse sections. Results Administering Adriamycin at 6 mg/kg on days 7 and 8 had the most teratogenic effect, with 80% of fetuses having 3 or more VACTERL anomalies: anorectal malformation, 100%; tracheoesophageal malformation, 50%; right-sided aortic arch, 58.3%; bladder agenesis/bilateral hydronephrosis, 100%. Conclusion This study establishes a mouse model that should provide insights into the cellular and molecular mechanisms underlying VACTERL anomalies.

Density of Muscle Spindles in Prosimian Shoulder Muscles Reflects Locomotor Adaptation

We examined the correlation between the density of muscle spindles in shoulder muscles and the locomotor mode in three species of prosimian primates: the slow loris (Nycticebus coucang), Garnett’s galago (Otolemur garnettii), and the ring-tailed lemur (Lemur catta). The shoulder muscles (supraspinatus, infraspinatus, teres major, teres minor, and subscapularis) were embedded in celloidin and cut into transverse serial thin sections (40 µm); then, every tenth section was stained using the Azan staining technique. The relative muscle weights and the density of the muscle spindles were determined. The slow loris muscles were heavier and had sparser muscle spindles, as compared to Garnett’s galago. These features suggest that the shoulder muscles of the slow loris are more adapted to generating propulsive force and stabilizing the shoulder joint during locomotion and play a less controlling role in forelimb movements. In contrast, Garnett’s galago possessed smaller shoulder muscles with denser spindles that are suitable for the control of more rapid locomotor movements. The mean relative weight and the mean spindle density in the shoulder muscles of the ring-tailed lemur were between those of the other primates, suggesting that the spindle density is not simply a consequence of taxonomic status.

COMPARISON OF MICROTHRIX ULTRASTRUCTURE AND MORPHOLOGY ON THE PLEROCERCOID AND ADULT SCOLEX OF CALLIOBOTHRIUM CF. VERTICILLATUM (TETRAPHYLLIDEA: ONCHOBOTHRIIDAE)

The distal bothridial surfaces of adult triloculate onchobothriids are covered with short structures that have been tentatively classified as very short filitriches, but this hypothesis has never been tested. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate microthrix morphology in the plerocercoid and adult forms of Calliobothrium cf. verticillatum, a triloculate onchobothriid tapeworm from Long Island Sound (Connecticut). Plerocercoids of C. cf. verticillatum were collected from the anterior midgut ceaca of Pagurus pollicaris Say, 1817 (flat-clawed hermit crab), and adults were collected from the spiral intestine of the dusky smooth hound Mustelis canis (Mitchell, 1815). Two plerocercoids and 2 adults were examined using SEM; 2 plerocercoids and 2 adults were examined using TEM. Microthrix distribution and morphology (including measurements of total length, base length, shaft length, and base width) were investigated on all surfaces of the plerocercoid and adult scolex. Slender filitriches and large bladelike spinitriches were observed extending from the tegument of plerocercoid and adult forms. The filitriches were found to have significantly narrower bases than the spinitriches (65-167 nm vs. 466-1,936 nm, respectively). The scolex proper of the plerocercoid and adult forms were found to have filitriches of medium-length and bladelike spinitriches. The distal bothridial surfaces differed dramatically in microthrix morphology between plerocercoid and adult forms; on the distal surfaces of the plerocercoids were long filitriches and bladelike spinitriches. However, the distal surfaces of the adults had short structures (previously hypothesized to be short filitriches) and a few bladelike spinitriches. Serial transverse sections revealed that the short structures on the distal bothridial surfaces of the adults were homologous with filitriches. They included all of the structural components of a filithrix as well as a base width that conformed to the filitriches found on other surfaces. The bothridial margins of the plerocercoid and adult forms had a microthrix pattern similar to that seen on the proximal bothridial surfaces except that the filitriches on the margins were significantly longer than those found anywhere else on the bothridia. The most dramatic difference between the plerocercoid and adult forms occurred on the distal bothridial surfaces, where the filitriches of the adult cestodes were significantly shorter and narrower, and the spinitriches were almost entirely lacking.

Adriamycin mouse model: a variable but reproducible model of tracheo-oesophageal malformations

A spectrum of tracheo-oesophageal malformations is seen in humans: oesophageal atresia, tracheal agenesis and laryngotracheo-oesophageal clefts. They are thought to share a common but unknown aetiology. These birth defects are frequently associated with other VACTERL anomalies. The adriamycin rat model (ARM) has proved to be a valuable model of the VACTERL anomalies, illustrating the dysmorphogenesis of oesophageal atresia and tracheal agenesis. As organogenesis relies on temporaspatially co-ordinated signalling systems, the next step would be to study the molecular pathogenesis of tracheo-oesophageal malformations. However, the mouse is the foremost mammal studied by developmental biologists, offering an expanding wealth of knowledge and scientific research techniques with which to investigate these anomalies. A limited dose response analysis of the teratogenicity of adriamycin in the mouse has identified a dose and timing of injections that produced tracheo-oesophageal malformations and other VACTERL anomalies. A clear account of the types and variability of the tracheo-oesophageal malformations produced by this dose is essential in order to be able to plan and interpret any future investigations of early gestation fetuses. CBA/Ca mice were accurately time-mated (n = 10). Nine dams received intraperitoneal injections of adriamycin (6 mg/kg) and one control dam received saline injections, on days 7 and 8. Fetuses were harvested on day 18, near term. Tracheo-oesophageal malformations were examined by dissecting microscope and serial transverse sections. Results are reported in the standard teratological manner as mean percentage per litter (+/-SEM). The resorption rate of the adriamycin treated fetuses was 50.4%. There were 29 adriamycin treated fetuses for inspection. Tracheo-oesophageal malformations were found in 29.2% (+/-10.3), affecting five out of nine litters. Oesophageal atresia occurred in 15.6% (+/-8.1), laryngotracheo-oesophageal cleft in 10.4% (+/-7) and tracheal agenesis in 3.1% (+/-3.1). All of these malformations occurred with a tracheo-oesophageal fistula. Unlike the ARM, the AMM can produce fetuses with complete laryngotracheo-oesophageal cleft as well as oesophageal atresia or tracheal agenesis. Their occurrence was found to be reproducible but variable. These are important considerations when planning and interpreting experiments using this model.

Late Silurian brachiopods from Darhan Mumingan Joint Banner, Inner Mongolia

Seven brachiopod species (including three new species) and three undetermined forms are described and figured here from an unnamed stratigraphic unit which mainly consists of argillaceous and bioclastic limestone near the stratotype of the Late Silurian Xibiehe Formation of the Xibiehe section in the Darhan Mumingan Joint Banner, north of the Bateaobao area, Inner Mongolia. Three new species, Eoschizophoria minuta, Navispira navicula and Howellella asiatica are established with transverse serial sections for their interiors. All brachiopod taxa described here show that this unnamed stratigraphic unit is higher than the Late Silurian Xibiehe Formation in the Xibiehe section and is possibly transitional between the Late Silurian and the Early Devonian. Authors temporarily regard this unit as the upper part of the Xibiehe Formation in this paper.

Histomorphological evidence of muscle tissue damage and recording area using coiled and straight intramuscular wire electrodes

While intramuscular wire electrodes (IWE) for the measurement of neuromuscular function offer high spatial resolution for examining single motor unit activity, the resulting damage to muscle tissue and mechanical instability should be considered. We examined the influence of IWE type and component parts on muscle damage using light microscopy in rats and confirmed that intramuscular pressure influences the mechanical stability of IWE. Three types of electrode, coiled electrodes with or without suture material inside and a straight electrode, were inserted into the soleus, gastrocnemius and tibialis anterior muscles. Transverse serial sections (5 microm) of these muscles in the vicinity of the electrodes were stained with haematoxylin and eosin. Less structural damage was observed in the vicinity of the recording points (leading-off surface; 50 microm diameter) for all electrode types compared to the electrode body. No differences in the extent of tissue damage were observed around the recording points for all electrodes. However, compared to straight electrodes, the extent of damaged tissue around the bodies of coiled electrodes was significantly (P < 0.0001) greater. The average distance between the recording points and the electrode body was <1 mm for all electrodes. Intramuscular pressure at rest and maximal twitch contraction were 1.1 +/- 0.5 and 49.4 +/- 4.0 mmHg, respectively. Coiled IWEs became well integrated with muscle fibres, stabilizing electrode localization and facilitating electromyographic recordings without causing significant muscle damage.

Impairment of transneuronal traffic in Streptozotocin-induced diabetes, a WGA-HRP neurohistochemical study in the rat

Retrograde transport of Wheat germ agglutinin conjugated to Horseradish peroxidase (WGA-HRP) was used in labeling vagal neurons projecting to the stomach from the dorsal motor nucleus of the vagus nerve (DMNV) in Streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in the experimental rats by intraperitoneal injection of buffered STZ. Control rats were injected with an equivalent volume of the citrate buffer not containing STZ. The experimental rats, which became diabetic about 24 h after intraperitoneal injection of STZ, were kept alive for a period of 24 weeks to attain a chronic state of diabetes. Control euglycaemic rats were also kept alive for 24 weeks. At the end of 24 weeks, the two groups of rats were prepared for stomach surgery. Following anaesthesia laparotomy was performed and the stomach exteriorized. The anterior and posterior walls of the stomach were injected with 0.1 ml of 5% WGA-HRP in 0.5 M sodium chloride. Experimental and control rats were sacrificed 48-72 h after tracer injection by transcardial perfusion with normal saline, fixative and buffered sucrose. Transverse serial frozen sections of the brainstem were processed for WGA-HRP neurohistochemistry and analyzed under light and dark-field microscopy. The analyses of the sections taken from the chronic diabetic rats revealed fewer WGA-HRP labeled neurons in the DMNV than sections taken from the control euglycaemic rats. The depletion of labeled neurons in the diabetic rats compared with the euglycaemic rats is indicative of an interference with the mechanism of retrograde neuronal transport of WGA-HRP by chronic diabetic state.

Life‐history strategies of a species of Catenipora (Tabulata; Upper Ordovician; southern Manitoba, Canada)

Detailed study of coralla by transverse serial sections permits the determination and evaluation of life-history strategies (survival and growth characteristics) in response to different physical environments, for Catenipora foerstei Nelson, 1963 from the Selkirk Member, Red River Formation, in Manitoba. We recognize various modes of corallite increase: one type of axial increase, four types of lateral increase, and agglutinated patches of corallites in association with normal, undamaged corallites; and one type of axial increase, one type of lateral increase, and temporary agglutinated patches from the recovery processes of corallites damaged by sediment or bioclast influx. In addition, the formation of new ranks by lateral increase is the most effective method for rapid growth of a corallum or for reconstructing part of a corallum damaged by physical disturbances. Fluctuations in the tabularial area of corallites occur in cycles over vertical intervals ranging from 3.20–7.90 mm. We consider each cycle to represent annual growth. Average annual growth of the three coralla ranges from 4.20–6.27 mm. According to correlations between annual growth cycles and other growth characteristics, a high frequency of offsetting is associated with rapid vertical growth. Specifically, annual growth is relatively high in association with episodes of sediment or bioclast influx, probably generated by storms. In some coralla, however, annual growth is highest in the cycle characterized by few new corallites or by extraordinarily high rates of offsetting by normal, undamaged corallites as well as damaged corallites. This suggests that vertical growth could also be affected by factors other than storm-related disturbance.

The atrioaortic, atrioventricular, and ventriculoaortic septae in the human heart

We demonstrated in the canine heart that there are heretofore unknown septae separating regions of the right atrium and right ventricle from the aorta at the level of the right (*) and posterior aortic sinus (· PAS) and separating the right atrium from the left ventricle. Here we report the septae in the human heart in a stereotaxic study. Methods and Results Photographs of the epi- and endocardial exposure of whole and flattened hearts and during blocking (8) were compared to photographs of serial orthogonal transverse plane histologic sections stained by Goldner Trichrome (5). Every section was mounted, accessioned and initially evaluated at .5 mm intervals. In human hearts, the same structures and relationships in dog heart differed only in size and pitch. For the septae, the atrioaortic septum extends between the right atrium at the level of an aortic sinus wall; the ventriculoaortic septum (VAS) extends between the right ventricle at level of an aortic sinus wall (Figure, VAS is in the PAS); and the atrioventricular septum-membranous and -muscular components extend between the right atrium and the left ventricle. The membranous ventricular septum extends under the right and posterior aortic sinuses. Conclusions The septae separate low- from high-pressure chambers and can be at risk of breech or puncture with pathology or during cardiac procedures and help to explain rupture of the right sinus of Valsalva into the right ventricular outflow tract imaged via transesophageal echocardiograms (Cullen et al., Circulation, 2002: –e2). Support: NIH HL073261 (DKR).

Atrial myocardium and the atrionodal bundles evoke distinct plateau action potentials

Our previous studies showed: electrograms traces made with wire (WE) and catheter electrodes (CE) at sites where the atrial and specialized tissues overlap contain waveforms evoked by both tissues. At the atrionodal bundle (AB) site, the so-called low-high amplitude (amp) potentials are seen. The low waveforms reflect AB activation, which persists with high K, the high-amp potentials reflect atrial activation and ceased with high K. Transmembrane potentials (TAPs) made deep to WE at sites where coincident CE and WE traces are found, showed AB TAPs are plateau-shaped and atrial potentials (Ap) are triangular. Using coincident CE, WE, and ME recordings for targeting ABs for Lucifer Yellow (LY) iontophoresis/photoablations, we found some plateau potentials were coincident with the high-amp Ap. Here we report the electrical and anatomic features of myocytes revealed by LY. Methods and Results Standard methods were used for CE and WE recordings in the unipolar mode and for TAPs. Myocytes targeted by their TAPs were LY injected for 10 mins using 20 to 40 nA hyperpolarizing current. Goldner trichrome and unstained serial transverse sections were viewed by light and epifluorescent microscope. LY was confined to (a) sub-endocardial atrial fascicles when coincident high-amp WE, CE and triangular TAPs were targeted; (b) sub-epicardial atrial fascicles when high-amp and plateau TAPs were targeted; and (c) AB fascicles when coincident low-amp and plateau potentials were targeted. The AB potentials displayed a more prominent spike phase 1 and dome than the atrial plateaus. Conclusions Some ordinary atrial myocytes possess plateau potentials. Coincident CE, WE, and ME recordings are essential for delineating the atrial from the AB myocytes for in-vitro studies. Support: NIH HL073261 (DKR).

Computer simulation analysis of normal and abnormal development of the mammalian diaphragm.

BackgroundCongenital diaphragmatic hernia (CDH) is a birth defect with significant morbidity and mortality. Knowledge of diaphragm morphogenesis and the aberrations leading to CDH is limited. Although classical embryologists described the diaphragm as arising from the septum transversum, pleuroperitoneal folds (PPF), esophageal mesentery and body wall, animal studies suggest that the PPF is the major, if not sole, contributor to the muscular diaphragm. Recently, a posterior defect in the PPF has been identified when the teratogen nitrofen is used to induce CDH in fetal rodents. We describe use of a cell-based computer modeling system (Nudge++™) to study diaphragm morphogenesis.Methods and resultsKey diaphragmatic structures were digitized from transverse serial sections of paraffin-embedded mouse embryos at embryonic days 11.5 and 13. Structure boundaries and simulated cells were combined in the Nudge++™ software. Model cells were assigned putative behavioral programs, and these programs were progressively modified to produce a diaphragm consistent with the observed anatomy in rodents. Homology between our model and recent anatomical observations occurred under the following simulation conditions: (1) cell mitoses are restricted to the edge of growing tissue; (2) cells near the chest wall remain mitotically active; (3) mitotically active non-edge cells migrate toward the chest wall; and (4) movement direction depends on clonal differentiation between anterior and posterior PPF cells.ConclusionWith the PPF as the sole source of mitotic cells, an early defect in the PPF evolves into a posteromedial diaphragm defect, similar to that of the rodent nitrofen CDH model. A posterolateral defect, as occurs in human CDH, would be more readily recreated by invoking other cellular contributions. Our results suggest that recent reports of PPF-dominated diaphragm morphogenesis in the rodent may not be strictly applicable to man. The ability to recreate a CDH defect using a combination of experimental data and testable hypotheses gives impetus to simulation modeling as an adjunct to experimental analysis of diaphragm morphogenesis.

Effects of 12 days of artificial rearing on morphology of hypoglossal motoneurons innervating tongue retrusors in rat

The purpose of this study was to examine the influence of reduced tongue activity by artificial rearing on the morphology of motoneurons innervating the extrinsic tongue retrusors. Artificially reared rat pups were fed via gastric cannula from postnatal day 3 to postnatal day 14. Artificially reared animals and dam-reared controls had cholera toxin (subunit B) conjugate of horseradish peroxidase injected into the styloglossus to label motoneurons innervating hyoglossus and styloglossus on postnatal day 13 and postnatal day 59. Following perfusion on postnatal days 14 and 60, serial transverse sections treated with tetramethyl benzidine and counterstained neutral red were used to analyze motoneuron morphology. The shorter diameter of hyoglossus motoneurons increased with age for the dam-reared but not the artificially reared group. There was a tendency for a similar pattern for styloglossus motoneurons across the two rearing groups. The changes in form factor reflected the changes in shorter diameter for both motoneuron pools. Therefore, reducing suckling activity during normal postnatal development leads to diminished motoneuron somal growth in rats. This may also be the case in premature infants necessarily fed artificially.

Histological characterization of Sticholecitha serpentis Prudhoe, 1949 (digenea, bieriidae, sticholecithinae), parasite of Bothrops moojeni Hoge, 1966 (serpentes, viperidae)

The aim of this study was to evaluate the morphology of the species Sticholecitha serpentis Prudhoe, 1949 by means of histological procedures. Helminths were previously fixed in Railliet & Henry solution, uncompressed and were included in 2-hydroxyethyl-methacrylate. Longitudinal and transverse serial sections with a 4-mm thickness were performed in a microtome (Leica RM 2165), stained with haematoxylin-eosin and then analyzed in a computerized image analysis system (Qwin Lite 2.5, Leica). Structures of systematic value, such as oral sucker, acetabulum, prepharynx, pharynx, esophagus, intestinal caeca, vitelline glands, ovary, uterus, cirrus pouch and testicles were described. Structures that were poorly visible in total preparations were also observed and described, such as efferent ducts, ejaculatory duct, prostate, seminal vesicle, seminal receptacle, Laurer’s channel, Mehlis’ gland, vitelline ducts, metraterm, genital atrium, digestive glands and excretory vesicle. We demonstrated that histological analysis can supply important data regarding the morphological characterization of S. serpentis and will be able to contribute to systematic studies of trematodes.

Immunhistochemical Demonstration of Lumbar Intervertebral Disc Innervation in the Dog

Low back pain is a common ailment in dogs, particularly in specific breeds as for instance the German shepherd dog. A number of structures such as facet joint capsules, ligaments, dorsal root ganglia, periosteum, vertebral endplate, and meninges have been associated with this condition. However, in a substantial proportion of all cases, the origin of pain remains obscure. A further structure often being involved in vertebral column disorders is the intervertebral disc. However, the presence of nerves is a precondition for pain sensation and, consequently, structures lacking sensory innervation can be left out of consideration as a cause for low back pain. Nerve fibres have been demonstrated at the periphery of intervertebral discs in man, rabbit and rat. With regard to the dog, however, extent of intervertebral disc innervation still is disputed. The goal of the present study, therefore, was to assess previous findings based on silver impregnation. Protein gene product (PGP) 9.5 was used as a marker for immunohistochemical examination of serial transversal and sagittal paraffin sections of lumbar discs from adult dogs. This technique revealed nerve fibres to be confined to the periphery of the intervertebral discs. Thus, even limited pathological processes affecting the outer layers of the intervertebral disc are prone to cause low back pain.

The Effect of an Extended Flexor Carpi Radialis Approach on Blood Flow to the Distal Radius: A Cadaveric Study

The effect of an extended flexor carpi radialis approach on the blood supply of the radius was examined in six (3 paired) fresh frozen cadaver limbs after injection with India ink and clearing using a modified Spalteholz technique. An extended flexor carpi radialis approach to the distal radius was made in the left limb in each of the three-paired limbs. The right limb served as a nonoperative control. Following perfusion of the arterial vasculature of each limb with India ink, serial transverse sections were cut and the intraosseous blood supply evaluated using a modified Spalteholz technique. Both controls and surgical specimens demonstrated complete cortical penetration from endosteal vessels in the proximal and midsections of the radius. In the distal radius, surgical specimens demonstrated reduced perfusion volarly, however there continued to be perfusion of ink through intact dorsal and ulnar metaphyseal perforating arteries. Persistent vascular perfusion to the distal radius remains through intact endosteal vessels and metaphyseal perforators of extensive surgical soft-tissue stripping.

The thyroid tissue of juvenile Oncorhynchus mykiss is tubular, not follicular

The three dimensional morphology of the thyroid tissue in juvenile rainbow trout Oncorhynchus mykiss was determined using serial transverse and longitudinal sections of lower jaws stained with haematoxylin and eosin. The thyroid tissue comprised interconnecting tubular units not the follicles that are widely described in the literature. Some of these tubules were subdivided by branching, giving the appearance of follicles in the sections. The thyroid tissue was aggregated into two major concentrations of tissue, associated with the first and second branchial arteries, with the majority of the tissue located dorsal and lateral to the aorta. These observations in juvenile rainbow trout suggest that thyroid tissue of some species of fishes may not be follicular, as previously assumed. The physiological and evolutionary implications have yet to be determined.

Penicillin Reduces Eustachian Tube Gland Tissue Changes in Acute Otitis Media

The volume of the mucous paratubal glands and the number of the mucus-producing goblet cells in the middle ear and Eustachian tube (ET) are increased after experimental acute otitis media (AOM). The present investigation examines a potential effect of penicillin on the changes in goblet cell density and gland structures of the ET during and after AOM. Middle ear inoculation of Streptococcus pneumoniae in 50 rats. Two days later, 25 rats were given penicillin V as one daily dose for 5 days. Twenty-five rats received no treatment. Five animals from each group were sacrificed on days 4, 8, 16, 90, and 180. The ET was dissected and decalcified, followed by paraffin embedding, serial transverse sectioning, and PAS/alcian blue staining. The goblet cell density and the paratubal gland composition and volume were determined in every 20th section, using a light microscope. Penicillin reduced the increase of goblet cell density from day 8 and through 6 months, whereas the increase of the paratubal mucous gland volume was unaffected by treatment. We conclude that penicillin reduces the increase of ET goblet cell density during and after acute otitis media, whereas the paratubal gland volume remains unaffected. An increased mucosal secretory capacity and indicated excessive secretion of mucus may contribute to the deteriorated ET function found after AOM and thus predispose, sustain, or aggravate middle ear disease. This may be prevented by penicillin treatment.