bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in the testicular microvasculature during photoperiod‐related seasonal transition from reproductive quiescence to reproductive activity in the adult golden hamster
Authors: Mayerhofer Artur , Hikim Amiya P. Sinha , Bartke Andrzej , Russell Lonnie D. 
Published: February 2005

AbstractThe structure and permeability of the testicular microvasculature in the adult golden hamster during different phases of gonadal activity was examined. After 12 weeks of exposure to a short photoperiod (SD; 6L:18D), maximal testicular regression with over tenfold reduction in size was achieved as compared with active tests of animals maintained in long photoperiod (LD; 16L:8D). Testes weights and volumes in regressed testes were not significantly different from the values measured in animals undergoing early recrudescence (transfer from SD to LD for 1 or 2 weeks). The volume density of testicular blood vessels and their lumina did not differ significantly between fully gonadally active, fully regressed animals or those transferred from SD to LD for 2 weeks. However, in animals transferred for 1 week from SD to the stimulatory LD, the density of testicular blood vessels and vascular permeability to the endothelial tracer horseradish peroxidase were significantly increased, as compared to all other groups. An angiogenic process was observed by electron microscopy, which was initiated in the regressed gonad and which was prominent 1 week after transfer from SD to LD, but it was less conspicuous 2 weeks after transfer from SD to LD. The angiogenic process was characterized by activated developing blood vessels with a basal lamina and a lumen, which was formed by dilatation of an interendothelial space. There were two types of endothelial sprouts: the first with one layer of basal lamina, indicating true neovascularization, and the second with additional layers of basal lamina. In the latter, the presence of a superfluous basal lamina indicates that regeneration takes place along the path of old vessels. In fully regressed animals isolated basal‐lamina‐like structures were observed. Basal laminae are known to survive endothelial cell death, and these basal laminae later appear to serve as a scaffold for regeneration of new vessels. The rapid renewal of the testicular microvasculature under physiological stimuli suggests that the recrudescing testis of the golden hamster can be viewed as a physiological model of angiogenesis.
Neurons of origin of the internal ramus of the rabbit accessory nerve: Localization in the dorsal nucleus of the vagus nerve and the nucleus retroambigualis
Authors: Kitamura Seiichiro , Nishiguchi Takahiko , Ogata Kimio , Sakai Akira 
Published: February 2005

AbstractThe neurons of origin of the internal ramus of the rabbit accessory nerve were identified in the dorsal nucleus of the vagus nerve, using bilateral injections of horseradish peroxidase into the inferior vagal ganglion, soft palate, and pharynx, which were preceded by different combinations of the unilateral intracranial severings of the rootlets of the vagus and glossopharyngeal nerves, those of the cranial root of the accessory nerve, and the trunk of its spinal root. The neurons of origin occupied the caudal four‐fifths of the dorsal vagal nucleus extending from about 1.0 mm rostral to the obex as far caudally as the second cervical spinal segment, with their number being about half the total number of neurons of the nucleus. Although considerably fewer, they were also located in the nucleus retroambigualis of the first cervical spinal segment and the second segment. Axons of most internal ramus neurons traversed the rootlets of the cranial accessory root. Axons of the few neurons located more caudally than about 1.0 mm caudal to the obex emerged from the upper cervical spinal cord to run along the trunk of the spinal accessory root before finally joining the internal ramus; caudal to the midlevel of the first cervical segment, the dorsal vagal nucleus and the nucleus retroambigualis contained neurons whose axons followed only that course.
Structural assessment of rat sciatic nerve following tourniquet compression and vascular manipulation
Authors: Nitz Arthur J. , Dobner Joseph J. , Matulionis Daniel H. 
Published: February 2005

AbstractIn a recent study (Nitz et al., Exp Neurol 94:264–279, 1986) the validity of a rat animal model to examine effects of tourniquet compression and vascular occlusion on limb motor function, leg girth, and electrophysiologic changes was established. Here we report observations on sciatic nerve morphologic and morphometric alterations of these same animals. The hindlimbs of 90 rats were compressed by a pneumatic tourniquet at clinically relevant pressures (200 to 400 mm Hg) for 1 to 3 hours, and the sciatic nerve was assessed by light and electron microscopy at 1, 3, and 6 weeks post compression. The nerves were also examined from five additional animals at each of these time intervals following arterial ligation and sciatic nerve epineurectomy (30 rats). Percentage of degenerating myelinated nerve fibers and volume fraction of mast cells and fibroblasts were quantified morphometrically. The percentage of degenerating myelinated nerve fibers after moderate to severe tourniquet compression and vascular manipulation was similar and ranged from 15% to 45%. Tourniquet compression, but not vascular occlusion, resulted in an increase of mast cells and fibroblasts and disruption of endothelial cells of endoneurial vessels. The results suggest that clinically relevant tourniquet compression causes a secondary increase in vascular permeability, intraneural edema, and subsequent prolonged tissue ischemia, resulting in nerve degeneration.
An analysis of the popliteus muscle in man, dog, and pig with a reconsideration of the general problems of muscle function
Authors: Fuss Franz K. 
Published: February 2005

AbstractOn the basis of general considerations of muscle functions and by means of mechanical and measuring methods and by computer analysis, it is shown that the popliteus muscle of man, dog, and pig is basically an extensor, regardless of whether femur or tibia are considered as resting. The traditional doctrine claiming a flexor function of the popliteus muscle has to be revised. In spite of the basic extending function, its effect in actual extension, especially against the weight of the entire body, is evidently most doubtful. Never has its rotatory function been doubted. Its role in reversing the compulsory rotation at the beginning of flexion can now easily be explained: since it is an extensor, the flexion would cause its passive elongation, against which its mere tonus causes rotation.
A method for sampling the stages of amelogenesis on mandibular rat incisors using the molars as a reference for dissection
Authors: Smith C. E. , Nanci A. 
Published: February 2005

AbstractA method for locating specific stages of amelogenesis on continuously erupting incisors was devised for rats weighing 101 ± 5 g (n = 32). The technique is based on reflecting reference lines from the mandibular molars as perpendiculars to the labial surface of mandibular incisors. From these reference lines additional measurements are then made along the midline of the labial surface of the incisor in an apical or incisal direction of find the site desired for sampling. Histological studies on 24 decalcified incisors split into segments by using such reference lines and reconstructed by morphometry indicated that a reference line reflected from the contact point between the 2nd and 3rd molars crossed the enamel organ and adjacent enamel at 3,181 ± 329 μm incisal to the start of the secretory zone of amelogenesis. A reference line from the 2nd and 1st molars crossed the enamel organ and enamel at 1,238 ± 424 μm incisal to the start of the maturation zone of amelogenesis, while a reference line from the mesial side of the 1st molar crossed the enamel organ and enamel almost exactly where the enamel becomes completely soluble following prolonged decalcification in EDTA. Although reference lines were reproducible within a group of male rats having similar body weights, the linear distance between the apical end of the incisor and the point at which they crossed the tooth increased at a rate of 1 mm per 159 g for rats between 50 and 300 g body weight. This suggests that molars do not maintain a fixed relationship to incisors over time, and extreme care must be taken to standardize an experiment to a specific body weight when using this method.
Anatomic distribution of autonomic neural tissue in the developing dog heart: I. Sympathetic innervation
Authors: Ursell Philip C. , Ren Chao Ling , Danilo Peter 
Published: February 2005

AbstractWe used immunocytochemical localization of tyrosine hydroxylase to trace the ontogenesis and anatomic distribution of sympathetic innervation in fetal, neonatal, and mature canine hearts. Sparse tyrosine hydroxylase‐positive neural tissue first appeared in the atrium, including sinoatrial and atrioventricular nodes, and the ventricular epicardium at midgestation and progressively increased in extent to reach the adult pattern by 2 months following birth. Sympathetic innervation of the atrioventricular bundle occurred relatively later, with no nerve processes in the neonate but a mature pattern by 2 months. At each developmental stage the atria contained more tyrosine hydroxylase‐positive neural tissue than the ventricles. Thus, sympathetic nerve processes appear in the developing canine heart earlier than was previously recognized. The time course of sympathetic innervation as defined by this anatomic study is in accord with electrophysiologic studies indicating progressive neonatal development of sympathetic effect which achieves maturity by 2 months of age.
Absence of an osseous patella and other observations in Macropodidae stifle
Authors: Holladay Steven D. , Smith Bonnie J. , Smallwood James E. , Hudson Lola C. 
Published: February 2005

AbstractThe patella is a large sesamoid bone that typically develops in the tendon of insertion of the large extensor muscles of the stifle joint. Although present in almost all species of mammals and birds, it has been found to be absent in the red kangaroo and two wallaby species (family Macropodidae). In its place is a fibrocartilage pad, located in the tendon of the quadriceps femoris muscle. This structure is visible grossly, is palpable, and has the form normally expected of a bony patella. In addition, the femoral trochlea is shallow and asymmetric, and the lateral gastrocnemius sesamoid is unusually prominent. These and other related modifications in the area of the Macropodidae stifle are presented.
Visualization of sulfur‐containing components associated with proliferating chondrocytes from rat epiphyseal growth plate cartilage: Possible proteoglycan and collagen co‐migration
Authors: Landis William J. , Hodgens Karen J. 
Published: February 2005

AbstractElectron microscopy of epiphyseal growth plate cartilage from normal 4‐5‐week‐old rats has revealed extensive fibrillar aggregates and globules in the pericellular spaces of proliferating chondrocytes. These cells contained small globules and diffusely coiled, fine filaments located within large, membrane‐invested vacuoles. All such structures were observed after a variety of different tissue fixation regimes, including glutaraldehyde, osmium tetroxide, and potassium pyroantimonate. The fibrillar aggregates and globules were often overlapping and intermeshed and extended to 0.5 m̈m in length from their point of origin at cell membranes. Vacuoles were usually found at the periphery of cells, and some, by membrane fusion with the cell envelope, appeared contiguous with extracellular spaces wherein their contents could be discharged. Fine filaments and globules were occasionally observed in the Golgi complex and cisternae of endoplasmic reticulum of the chondrocytes. Further characterization of the cellular and pericellular components by electron microscopic radioautography, electron probe microanalysis, and electron spectroscopic imaging indicated the presence of sulfur, a result suggesting these aggregates, filaments, and globules in part represent proteoglycans in various stages of synthesis, secretion, and assembly. Additional radioautography utilizing 3H‐proline implied that filament bundles are also composed of collagen, a result posing the possibility that this protein and the putative proteoglycans may co‐migrate both intracellularly and within pericellular matrices. In extracellular matrices adjacent to cell lacunae, the fibrillar aggregates appeared in close association with typical collagen type II fibrils, an observation providing evidence for proteoglycan‐collagen network formation in this region of the rat epiphysis. These microscopic and analytical data in situ would support certain studies in vitro of proteoglycan‐collagen type II and IX association and are important in describing the interaction of such cartilage components ultimately involved in matrix formation.
Variation in histochemical enzyme profile and diameter along human masseter intrafusal muscle fibers
Authors: Eriksson Per‐Olof , Thornell Lars‐Eric 
Published: February 2005

AbstractThe histochemical enzyme profile of human masseter intrafusal muscle fibers was analyzed in consecutive serial cross sections along the individual fibers. Two hundred intrafusal fibers in 21 muscle spindles were classified.On the basis of equatorial nucleation, myosin ATPase‐staining reactions after alkaline and acid preincubations and diameter, four different populations or types of intrafusal fiber were identified: large‐diameter alkaline‐stable and acid‐stable fibers, bag2; two types of fiber with intermediate‐diameter, alkaline‐labile and acid‐labile fibers corresponding to bag1 and alkaline‐labile and acid‐stable fibers designated as AS‐bag1; and small‐diameter alkaline‐stable and acid‐stable (pH 4.6)‐acid‐labile (pH 4.3) fibers called chain fibers. Regional variability in staining and diameter along the individual fibers was noted. In general, intrafusal fibers showed stronger oxidative reactions than did extrafusal fibers.The enzyme profile of the human masseter intrafusal fibers differed from that of extrafusal fibers in jaw, limb, and trunk muscles and also from that reported for spindles in limb and trunk muscles in man. The result suggests unique properties of human jaw muscle spindles and the jaw motor system.
Isomyosin expression pattern during formation of the tubular chicken heart: A three‐dimensional immunohistochemical analysis
Authors: De Jong F. , Geerts W. J. C. , Lamers W. H. , Los J. A. , Moorman A. F. M. 
Published: February 2005

AbstractThree‐dimensional (3‐D) distribution of atrial and ventricular isomyosins is analysed immunohistochemically during the formation of the tubular chicken heart (stage 7 to 12 [H/H]) using antibodies specific for adult chicken atrial and ventricular myosin heavy chains, respectively. This analysis revealed that both types of isomyosins can be first detected at stage 8 (H/H, possessing four pairs of somites), i.e., when the heart primordium still exists as two separate cardiogenic plates. The ventricular type of isomyosin is initially expressed in those areas of cardiogenic plates in the vicinity of the anterior intestinal portal. The atrial type of isomyosin is initially expressed in zones caudal and lateral to the areas of ventricular isomyosin expression. Medial to the atrial isomyosin‐expressing areas, cardiogenic plate areas exist that initially lack myosin expression. Those parts of the cardiogenic plates that fuse in front of the anterior intestinal portal, thereby forming the heart tube, are characterized by the expression of both isomyosins; however, the caudolateral parts of the heart primordium maintain their single atrial isomyosin expression during further development. Cardiac contractions are therefore first observed at stage 10 (H/H, possessing ten pairs of somites) in myocardium that coexpresses both isomyosins.
Effect of occlusal functional forces on incisor socket morphology and location in the rat mandible
Authors: Brin Ilana , Steigman Shulamit , Michaeli Yael 
Published: February 2005

AbstractThe effect of functional occlusal stress on dimensional alterations of the rat incisor socket and mandible were studied from roentgenograms. In 12 rats, the lower left incisor was shortened twice weekly, whereas the lower right incisor was allowed to remain in contact with both upper incisors. Thus, the right incisors were subjected to hyperfunction, and the left ones, to hypofunction. The lower incisors of 16 rats with normal occlusal contact served as control. Following an experimental period of 3 months, the animals were killed and standardized radiographs were taken of the cleaned mandibles. Socket and mandibular dimensions were measured on magnified tracings of the roentgenograms. Socket area, its posterior length, posterior mandibular length, and gonial angle changed in the same direction under both hyper‐ and hypofunction. The anterior socket was relocated in opposite directions: under hyperfunction, it assumed a more inferior position, whereas in hypofunction, it moved superiorly. The angulation of the socket became significantly more acute under hyperfunction, whereas in hypofunction, this parameter remained unchanged. It is concluded that altered functional demands affect the morphology of the incisor socket and its location within the mandibular borders.
Skeletal structural adaptations to mechanical usage (SATMU): 1. Redefining Wolff's Law: The bone modeling problem
Authors: Frost H. M. 
Published: February 2005

AbstractFrom the nature of a bone's endload and its local surface strains, the theory computes a modeling operator, Gamma (Γ), that predicts whether mechanical factors will cause lamellar bone modeling drifts, and where and of what kind. A given mechanical bone strain history then provides a separate modeling rate function, \documentclass{article}\pagestyle{empty}\begin{document}$ \dot M $\end{document}, to specify the rate of such modeling drifts as fractions of the largest possible ones. Multiplying the two functions, e.g., Γ · \documentclass{article}\pagestyle{empty}\begin{document}$ \dot M $\end{document}, then predicts mechanically controlled bone modeling responses for cortical and trabecular bone, both quantitatively and qualitatively. The theory correctly predicts each of the 6 known “principal adaptations” of lamellar bone, which provide a critical test of any such theory for this organ.The theory accounts for biologic, biomechanical, and clinical‐pathologic knowledge not available in Wolff's time nor accounted for by most biomechanicians since. Existing proven methods can provide all numerical data needed to satisfy the theory's mathematical equations and already suggest provisional values for most of them. Its originator views the theory as the kernel of more and better theories to come rather than a finished work, a kernel that suggests a new and in some respects novel logical framework for analysing the problems, and a kernel that invites critique, refinement, and/or exploitation by others.
Absence of cartilage canals in the long bone extremities of four species of skeletally immature marsupials
Authors: Thorp B. H. 
Published: February 2005

AbstractThe cartilaginous epiphyses and physes from the bone extremities of four species of skeletally immature marsupials were studied. The microscopic and ultrastructural features of the marsupial tissues were compared with similar samples from a neonatal lamb and a 1‐day‐old chick. Chondrocyte differentiation and endochondral ossification appeared similar in physes from the marsupials, foetal lamb, and 1‐day‐old chick. However, unlike the lamb and chick, which both contained cartilage canals, there were no cartilage canals in the epiphyseal or physeal cartilage from the marsupials. Many of the epiphyseal chondrocytes from the marsupial specimens contained large lipid droplets. It is suggested that the lipids in marsupial chondrocytes may be utilized in metabolic pathways. Despite hypertrophy of chondrocytes, there were no epiphyseal ossification centers in the femoral heads of the marsupial specimens; this was possibly due to the absence of cartilage canals, which are considered a source of osteoproginator cells. This study indicates that physeal and epiphyseal cartilage in marsupials is viable and functions in an avascular environment; this may be due to unique metabolic properties of the chondrocytes.
Ultrastructural localization of acetylcholinesterase in the guinea pig pineal gland
Authors: Luo Zhongrong , Schultz Robert L. , Whitter Ernest F. 
Published: February 2005

AbstractThe ultrastructural localization of acetylcholinesterase (AChE) activity in guinea pig pineal gland was studied using the copper‐glycine procedure. A small number of pinealocytes and bundles of unmyelinated nerve fibers were labeled by the AChE reaction. The AChE‐positive pinealocytes were located near blood vessels and distributed in small groups. The AChE reaction product was localized in the perinuclear cistern, in the cisternae of the endoplasmic reticulum (ER), and in the saccules of the Golgi apparatus. These findings suggest that the AChE‐positive pinealocytes synthesize AChE. The AChE reaction product was also seen in the intercellular space between pinealocyte processes. Besides pinealocytes, AChE activity was localized on the axolemma of myelinated and unmyelinated nerve fibers and in the basement membrane surrounding unmyelinated nerve fibers. Pseudocholinesterase activity was confined to Schwann cells, which showed the reaction product in their perinuclear cistern, in the cisternae of the ER, and on the plasmalemma.
Early testicular changes after vasectomy and vasovasostomy in Lewis rats
Authors: Flickinger Charles J. , Herr John C. , Howards Stuart S. , Sisak John R. , Gleavy Janice M. , Fusia Tod J. , Vailes Lisa D. , Handley Harold H. 
Published: February 2005

AbstractThe testes of Lewis rats were studied at intervals from 2 weeks to 3 months after bilateral vasectomy, vasectomy followed 1 month later by vasovasostomy, or sham operations. Aims were to determine the nature of early alterations after vasectomy, and to determine whether vasovasostomy after 1 month would result in reversal of vasectomy‐induced changes. Approximately one‐fourth of the testes in the vasectomy and vasovasostomy groups displayed histological changes, which consisted mainly of depletion of germ cells. The extent of the depletion varied greatly in different seminiferous tubules. In tests altered in this way, no abnormal infiltrations of lymphocytes, macrophages, or other cells were observed in the seminiferous epithelium or in the interstitium. The rete testis and straight tubules were normal in testes with altered seminiferous epithelium. A few testes in the vasectomy and vasovasostomy groups had necrotic centers. The results suggest that depletion of germ cells occurred as a result of shedding from the seminiferous epithelium into the lumen of the tubules. A cellular immune response, such as occurs in experimental allergic orchitis in other species, did not appear to be responsible for the observed loss of germ cells. This suggests a possible role for humoral antibody in this model, since there is an association between testicular changes and serum antisperm antibodies at longer intervals after vasectomy. Testicular alterations were not reversed by performance of a vasovasostomy 1 month after vasectomy.