bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeability of the diaphragmatic mesothelium: The ultrastructural basis for “stomata”
Authors: Leak Lee V. , Rahil K. 
Published: February 2005

AbstractThe topography and organization of cells lining the peritoneal surface of the diaphragm in normal and intraperitoneally injected mice have been studied by transmission and scanning electron microscopy and freeze‐fracture replication techniques. The mesothelial cells of the peritoneal surface of the diaphragm are organized into two discrete populations. A population of cuboidal cells are found in areas over the lymphatic lacuna (roof covering submesothelial lymphatic vessels) while the remaining areas (not covering lymphatic lacunae) of the diaphragm are lined by extremely flattened cells. The apical surfaces of both cuboidal and flattened mesothelial cells are covered with numerous microvilli. The lateral borders of the cuboidal cells are characterized by the presence of numerous filamentous processes which interlace with similar structures from adjacent cells to form intercellular gaps which overlie a thin layer of connective tissue. In addition to the intercellular gaps, special circular pores are found between the margins of several neighboring cells. The observations suggest that these circular pores are formed when cell margins of several lymphatic endothelial cells span the submesothelial connective tissue to form intercellular junctions with cell margins of several neighboring mesothelial cells lining the peritoneal surface of the diaphragm. The intimate intercellular contact between these two different cell types provides an open channel between the peritoneal cavity and the lumen of the diaphragmatic lymphatic vessels (lymphatic lacunae). It is suggested that these circular pores correspond to the “stomata” of von Reckling‐hausen. Intraperitoneally injected colloidal particles (biological carbon) and red blood cells are rapidly removed from the peritoneal cavity via the circular pores (stomata).
Insemination‐induced histolysis of the flight musculature in fire ants (solenopsis, spp.): An ultrastructural study
Authors: Jones Ruth G. , Davis Walter L. , Hung Akey C. F. , Vinson S. Bradleigh 
Published: February 2005

AbstractThe fine structure of the insemination‐induced flight muscle degeneration (histolysis) in the queen fire ant (Solenopsis spp.) has been investigated. Within 2 hours post‐insemination, degenerative changes are detectable in the most peripheral fasciculi of the fibrillar flight muscle. Histolysis proceeds internally with time. Myofibril (sarcomere) dissolution begins with myofilament breakdown and continues until only free Z‐line material remains. The latter subsequently disappears leaving, at the terminal stages, only nuclei, lamellar bodies (myelin figures), and tracheoles as residual myoid elements. Lysosomes and/or phagocytes do not appear to play a primary role in the initiation and continuance of this process.
Functional interpretations of the radiographic anatomy of the femora of Myotis iucifugus, Pipistrellus subflavus, and Blarina brevicauda
Authors: Dawson David L. 
Published: February 2005

AbstractRadiographs of right femora from 29 shrews (Blarina brevicauda) and 51 bats (27 Myotis lucifugus, 14 Pipistrellus subflavus) were analyzed to determine if bone in these small mammals conformed to Bassett's (′68) revision of Wolff's Law. Five external and four cortical dimensions were made on enlargements of radiographs of each femur. Comparative descriptions of the spongiosa are given.External dimensions appear to be determined genetically, and, in bats, are closely related to functional demands. Shrew femora retain a primitive mammalian morphology.No apparent relationship exists between animal weight and mid‐diaphyseal cortical thickness. Although differences in cortical thickness in bats suggest a possible relation between bone and pressure, no relationship is apparent in shrews; further, the comparative magnitude of these dimensions is similar in all three species, indicating genetic control mechanisms. Computations of maximal loading suggest that loading is so slight, that the inherent strength of bone tissue is adequate to resist mechanical deformation. However, there is evidence of cortical bone response to physiological demands.Inspection of the spongiosa also fails to provide evidence of conformity to Wolff's Law. Instead, the trabeculae appear to be related to physiologic factors, animal age, and inherited disposition patterns.Thus, there is no evidence that bone in these diminutive mammals responds to mechanical forces, and the applicability of Wolff's Law is not indicated. It is hypothesized that, as the mechanical forces are so minimal, intrinsic tissue strength is sufficient to resist mechanical deformation, and femoral anatomy in these species is dictated by genetic and inherent physiologic conditions.
The axial musculature of Pontoporia blainvillei, with comments on the organization of this system and its effect on fluke‐stroke dynamics in the cetacea
Authors: Strickler Timothy L. 
Published: February 2005

AbstractThe axial muscular system of Pontoporia blainvillei is described and compared with published reports of this system in other cetaceans. A comprehensive system for classification of axial muscles is presented, based on the studies of Slijper. A discrete obliquus capitis inferior is described for the first time in cetacea, and it is suggested that its absence in previous descriptions may have been due partly to dissection error. The major axial muscle‐masses are organized in a similar way in most cetaceans, comprising a set of tail elevators and depressors, and a set of tendons with similar actions on the flukes. The anatomy of the axial musculature does not support the idea that the upstroke is the main propulsive stroke in cetaceans, but suggests similar roles of the upstroke and downstroke in propulsion.
Scanning microdensitometry of glycogen zonation in the livers of rats adapted to a controlled feeding schedule and to 30, 60, or 90% casein diets
Authors: Richards William L. , van Potter R. 
Published: February 2005

AbstractThe effect of diet composition on diurnal changes in glycogen zonation patterns in rat liver was investigated in individually‐caged male Sprague‐Dawley rats adapted to the 2 + 22 controlled feeding and lighting schedule and to diets containing 30% casein/55% carbohydrates, 60% casein/25% carbohydrates, or 90% casein (30 rats/dietary group). Three rats from each dietary group were killed at the following times relative to the onset of feeding (0 min):−60, −30, 0, 15, 30, 45, 60, 90, 120, and 180 min. Glycogen in cryostat sections from the median and right lateral lobes of the liver was fixed and stained by standard techniques. The optical density of glycogen at points along the path between the central and portal veins of a given lobule was determined, and lobular glycogen gradients of replicate animals were integrated to form a composite lobular glycogen distribution profile. In the period from −60 to 0 min, liver glycogen levels were similar for rats on any of the diets, and the glycogen concentration was similar in periportal (P), midlobular (M), and centrilobular (C) hepatocytes. During the 0‐ to 45‐min period, diet‐related glycogen depletion occurred (90 > 60 ≫ 30% casein) by asymmetrical glycogen loss (P > M ≫ C hepatocytes) from the liver lobules. Similar food intake curves occurred for all diets. During the 45‐ to 180‐min period, asymmetrical glycogen accumulation began in lobular parenchymal cells (P > M ≫ C hepatocytes), and the rate of accumulation was related to dietary composition (30 > 60 ≫ 90% casein). The differential responses of parenchymal cells within liver lobules to physiological stimuli resulted in glycogen distributional changes that were rapid and of large magnitude. Our results are consistent with the hypothesis that periportal and midlobular hepatocytes are more metabolically responsive and active than centrilobular hepatocytes.
The ultrastructure of rapid‐frozen, substitution fixed parotid gland acinar cells of the mongolian gerbil (Meriones meridianus)
Authors: Ichikawa Atsushi , Ichikawa Misao , Hirokawa Nobutaka 
Published: February 2005

AbstractThe ultrastructure of gerbil parotid gland acinar cells studied by rapid freezing in liquid nitrogen and freeze‐substituting with OsO4 was similar in general to conventionally prepared tissue, but different in several aspects. Acceptable preservation was limited to about 10 μm of the surface; the secretory granule membrane was a single dense line, while all others were trilaminar; the dense‐cored secretory granule had a rim of low density which was homogeneous; there were many continuous profiles between the Golgi lamellae, vesicles, and vacuoles; and mitochondria were long and arborized.
The origin and differentiation of enteric neurons of the intestine of the fowl embryo
Authors: Allan I. J. , Newgreen D. F. 
Published: February 2005

AbstractNeuroblasts were identified histologically in the intestine of the fowl embryo of stages 25 to 35 (Hamburger and Hamilton, ′51). These cells occurred rostral to the umbilicus at stage 26, and appeared caudally in a wave that reached the coprodeum at stage 34. The presence of histologically unidentifiable neuronal precursors was studied by grafting onto the chorio‐allantoic membrane (CAM) short lengths of gut from embryos of stage 24 to 34. After growth in isolation on the CAM, the resultant gut grafts were examined histologically for enteric neurons. In these grafts, neuronal differentiation occurred in the gut as a wave moving caudally at about 40 ḿm/hr. This wave preceded by less than 12 hours the normal appearance of neuroblasts at any particular level of the intestine.The findings are discussed with regard to previous reports on the origin of enteric neurons. The most likely conclusion is that all enteric neurons in the fowl are derived from vagal neural crest. The results obtained with grafts containing neurons of Remak's nerve, in addition to intestine, suggest that lumbo‐sacral neural crest may give rise to some enteric supporting cells which, in the absence of normal enteric plexuses, differentiate as pigment cells. If lumbo‐sacral neural crest cells contribute to post‐umbilical enteric neurons, their differentiation requires the presence of vagal cells.A comparison of enteric neuronal density and distribution in short and long colo‐rectal grafts suggests that only the advancing front of the neuronal precursor wave is necessary to populate the remainder of the gut. This high proliferative potential in the wave‐front appears to decline on reaching the most caudal colo‐rectum and coprodeum.
Ultrastructure of merkel cells in the hard palate of the squirrel monkey (Saimiri sciureus)
Authors: Garant P. R. , Feldman J. , Cho M. I. , Cullen M. R. 
Published: February 2005

AbstractThe distribution and ultrastructure of Merkel cells in the hard palate was investigated in the squirrel monkey (Saimiri sciureus) after fixation by vascular perfusion. Merkel cells were clustered at the base of the epithelial rete pegs of the hard palate. They were characterized by concentrations of dense‐cored granules and closely associated intraepithelial nerve endings. Numerous spiny processes extending from the Merkel cell were intercalated with adjacent keratinocytes, probably serving to detect and amplify movement of adjacent cells. These spiny processes contained a rigid core of parallel microfilaments which were interrelated with cytoplasmic filament bundles located beneath the cell membrane. Transitional cells containing dense‐cored granules and well developed tonofibrils appear to be related to both Merkel cells and keratinocytes.The findings of this study suggest that Merkel cells are highly adapted for detection of movement in adjacent keratinocytes, as well as movement of the epithelium with respect to the underlying connective tissue.
The bicellular and reflexive membrane junctions of renomedullary interstitial cells: Functional implications of reflexive gap junctions
Authors: Majack Richard Allen , Larsen William James 
Published: February 2005

AbstractRenomedullary interstitial cells are loosely organized within the interstitial space surrounding collecting ducts, limbs of Henle, and capillaries of the rat renal medulla. These cells possess long processes, which interact with each other and with cell bodies to form bicellular tight, intermediate, and gap junctions. In addition, both cell bodies and cell processess “reflexive” gap and intermediate junctions. Possible functions of renomedullary interstitial cell membrane junctions are discussed. Particular attention is given to a consideration of the functional significance of “reflexive” gap junctions.
Structural remodelling of bat thyroid parafollicular (C) cells during development
Authors: Nunez Eladio A. , Gershon Michael D. 
Published: February 2005

AbstractThe development of bat parafollicular (C) cells was evaluated by electron microscopy from the time of early thyroid formation, through the neonatal period, to young adulthood. Parafollicular cells were relatively few in number (3%) at the earliest developmental stage examined, but increased with subsequent fetal stages, reaching a relatively stable level of 28% of parenchymal cell volume just prior to birth. Fetal parafollicular cells were packed with calcitonin granules. Following birth, however, parafollicular cells were totally or almost totally depleted of calcitonin granules. Moreover, another cell type that resembled the parafollicular cell was also found. This cell contained tiny granules which often contained two dense cores. Parafollicular cells of maturing, juvenile bats were characterized by the massive accumulation of secretory material within the cisternae of the rough surfaced endoplasmic reticulum and a great deal of autophagy. Remarkably, none of these changes were found in young, adult bat parafollicular cells. In conclusion, this study provides morphological evidence to support the view that parafollicular cells play a role in developing mammals.
Calcium and the secretory cycle of prolactin cells: A cytochemical and ultrastructural study of dopamine inhibition and monobutyryl cyclic AMP‐Stimulation of prolactin secretion
Authors: Yancey S. Barbara , Weiner Richard , Schechter Joel 
Published: February 2005

AbstractTo identify intracellular calcium pools that may be involved in the secretory process in prolactin (PRL) cells, hemi pituitaries were incubated in medium containing 10−6 M dopamine, 5 mM cyclic cAMP (experimentals), or in medium alone (controls) and then processed for electron microscopy using potassium pyroantimonate to localize intracellular calcium. PRL in the medium was measured by radioimmunoassay. The concentration of antimonate associated with mitochondria, Golgi saccules, and secretory granules was estimated. Dopamine inhibition of PRL secretion (>80% at 1, 2, 3 h) resulted in accumulation of secretory granules in all stages of maturation and dilation of Golgi saccules at 2 and 3 h, accompanied by increased mitochondrial antimonate and increased Golgi‐associated antimonate. Cyclic AMP stimulation of secretion (635% at 5 min., declining to 34% at 1 h) resulted in marked exocytosis at 5 and 15 min., declining after 30 min. Mitochondrial antimonate decreased after 30 min. Stimulated cells exhibited numerous coated membrane structures at or near exocytotic pits and an amassing of microvesicles at the margin of the Golgi apparatus. Although some secretory granules consistently exhibited reactivity to antimonate (unchanged by inhibition or stimulation), plasma membrane, and granule membrane translocated to the plasma membrane during exocytosis, were not reactive.
Three‐dimensional architecture of the cortical region of the golgi apparatus in rat spermatids
Authors: Hermo L. , Rambourg A. , Clermont Y. 
Published: February 2005

AbstractGlutaraldehyde‐fixed testes were impregnated with the Ur‐Pb‐Cu technique of Thiéry and Rambourg (′76) or postfixed in ferrocyanide‐reduced osmium (Karnovsky, ′71). Thin and thick (0.5 μm) sections were examined with a Philips 400 electron microscope at 80 or 100 kv. Stereopairs were prepared from pictures of the same field after tilting the specimen every 6° from the −45 degree to the +45 degree position of EM goniometric stage. The cortex of the compact hemispherical Golgi apparatus of young spermatids (steps 2–8) was found to be composed of saccular and intersaccular regions similar to those described in the Golgi apparatus of Sertoli cells (Rambourg et al., 1979). In the saccular region, the stacks were composed of three to nine parallel saccules perforated with pores of various dimensions. On the mature or trans‐face of the stack, one or two membranous elements with a wider lumen were either closely applied to the overlying saccules or were separated from them and intermixed with the vesicular components of the medulla. On the forming or cis‐face of the stack, three or four saccules were frequently interrupted by gaps in register from one saccule to another. In three dimensions, these gaps appeared as pan‐shaped spaces or “wells,” often containing a few vesicles. Immediately overlying the first saccule on the cis‐face, a regular network of anastomotic tubules was present, corresponding to the cis‐osmiophilic element observed in other cell types. In the intersaccular region, membranous tubules connected to the edges of the saccules branched, intertwined, anastomosed, and bridged adjacent stacks of saccules. Such membranous tubules bridged saccules with the cis‐osmiophilic element or saccules of the same stack. Between the ER cisternae capping the surface of the Golgi apparatus and the cis‐network of anastomotic tubules, there was a space called the peripheral Golgi region containing small vesicles and membranous tortuous tubules. The vesicles were frequently arranged in clusters that were capped by an ER cisterna and displayed a size gradient from the periphery to the center of the cluster. Thus, although there were similarities between the three‐dimensional architectures of the Golgi apparatus in Sertoli cells and young spermatids (e.g., saccular and intersaccular regions), several structural features distinguished the spermatid's Golgi apparatus.
Ultrastructural study of a blood‐muscle spindle barrier after systemic administration of horseradish peroxidase
Authors: Dow Pierre R. , Shinn Susan L. , Ovalle William K. 
Published: February 2005

AbstractThe permeability of the normal muscle spindle capsule to the entrance of an exogenous protein tracer was assessed by the use of horseradish peroxidase (HRP). Adult mice were injected intravenously with a solution of HRP (MW 40,000). After varying intervals, ranging from two to 240 minutes, animals were perfused aortically with fixative, and anterior tibialis muscles were removed, processed, and examined. The results were evaluated by electron microscopic cytochemical techniques, and attention was directed to the movement of tracer and its relationship to the outer and inner capsule of the muscle spindle.HRP was first demonstrated in cytoplasmic vesicles crossing the continuous capillary endothelium supplying the muscle spindle, and was then detected in the interstitial space surrounding the outer capsule. In polar regions, HRP had entered the periaxial space by two minutes, and it was seen in cytoplasmic vesicles of the attenuated outer capsule. Later, HRP abutted the sarcolemma of intrafusal fibers, and by 12.5 minutes there was evidence of tracer in T‐tubules of these muscle cells. Whereas at no time was tracer observed traversing any of the numerous intercellular junctions of the capsule, it appeared that polar regions were leaky and open‐ended at their distal portions.The sensory equatorial zone was considerably less permeable to the entrance of tracer. Whereas HRP was visible initially in cytoplasmic vesicles of the subjacent capillary endothelium, it was not until 12.5 minutes that tracer could be demonstrated within some vesicles of equatorial outer capsule cells. At later times, a small amount of HRP was observed in the equatorial periaxial space, where it was phagocytosed and finally sequestered by cells of the inner capsule as membrane‐bound lysosomal deposits. Consequently, at no time was tracer incorporated into either intrafusal fibers or their sensory nerve terminals.Thus, in contrast to polar regions, the muscle spindle capsule in the equatorial zone appears to be effective in preventing the indiscriminate penetration of HRP from the bloodstream. This suggests dissimilar paths of tracer movement from the microvasculature into sensory and non‐sensory regions of the muscle spindle.
EMG of the interosseous and lumbrical muscles in the chimpanzee (Pan troglodytes) hand during locomotion
Authors: Susman Randall L. , Stern Jack T. 
Published: February 2005

AbstractThe interosseous, lumbrical, and extensor digitorum communis muscles of the human hand constitute a complex apparatus that acts to move and stabilize the fingers during grasping and manipulation. A telemetered electromyographic study of these muscles in chimpanzees was undertaken to determine whether use of the hand in locomotion and to maintain postures might be associated with functional roles different from those in humans. The manual interossei of chimpanzees are recruited in metacarpophalangeal flexion and in rapid interphalangeal joint extension. Slow digital extension can be accomplished solely by the extensor digitorum communis and lumbricals. The highly variable activity of the interossei during knuckle‐walking is compatible with their roles as ab/adductors and rotators, but such movements could not be accurately assessed. It is concluded that the generalized suspensory and specialized terrestrial locomotion of the chimpanzee is not associated with major changes in the function of the manual interossei and lumbricals.
Scanning electron microscopic studies of the surface morphology of the vomeronasal epithelium and olfactory epithelium of garter snakes
Authors: Wang Ruu Tong , Halpern Mimi 
Published: February 2005

AbstractFixed vomeronasal and olfactory epithelia from normal adult garter snakes were microdissected, fractured, and examined with a scanning electron microscope. The method permits a detailed comparative study of the structural organization and morphological characteristics of the constituent cells of the vomeronasal and olfactory epithelia. Despite similarities in the nomenclature of the constituent cells in both epithelia, significant differences exist in their surface morphology. A unique columnar structure composed of non‐neuronal elements is present in the vomeronasal epithelium. These columns house the bipolar neurons and undifferentiated cells. Such a columnar organization is absent in the olfactory epithelium. In the vomeronasal epithelium the bipolar neurons possess microvillous terminals at their dendritic tips, while the dendritic tips of the bipolar neurons of the olfactory epithelium possess cilia. Vomeronasal supporting cells are covered with microvilli, while olfactory supporting cells are covered with cytoplasmic protuberances in addition to the microvilli. In the vomeronasal epithelium the pear‐shaped neurons have a grossly smooth surface and are organized into clusters, while in the olfactory epithelium the elliptical bipolar neurons are spinous, aligned side‐by‐side and interdigitate. The basal (undifferentiated) cell layer in the vomeronasal epithelium has a high packing density and is composed of several layers of irregularly shaped cells. In the olfactory epithelium the basal cell layer is loosely organized and composed of a single layer of oval cells. This information on the three‐dimensional cell structure of both epithelia provides a basis for experimental observations on changes in morphology of the bipolar neurons during genesis, development, maturation, degeneration, and regeneration in postnatal, adult animals.