bluuebunny/crossref_metadata_2025 huggingface dataset:
Microtubule‐granule relationships in motile human polymorphonuclear leukocytes
Authors: Ryder Mark I. , Weinreb Robert N. , Niederman Richard
Published: February 2005

We examined the relationship of microtubules to the granule organization in stimulated human polymorphonuclear leukocytes (PMNs). Electron microscopic (EM) observations of critical‐point‐dried PMNs revealed that only a portion of the granules appeared in close association to microtubules. These closely associated granules appeared to be attached to the microtubule via smaller‐diameter filaments. The remaining granules appeared either attached to microtubules at a further distance, via smaller‐diameter filaments such as actin, or unassociated with microtubules. EM observations of PMNs treated with either the microtubule promoter drug taxol or the mocrotubule depolymerization drugs nocodozole and colchincine revealed a redistribution of granules towards the nucleus. Granule clustering at the periphery of the cell was also noted with nocodozole and colchicine. With cytochalasin B, a uniform distribution of granules was noted. However, granule clustering was noted when PMNs were coincubated with cytochalasin B and colchicine. These results indicate that microtubules may have both a direct and indirect role (through other cytoskeletal elements) in the organization of PMN granules.
Ultrastructural evidence that specialized regions of the murine oviduct contribute a glycoprotein to the extracellular matrix of mouse oocytes
Authors: Kapur Raj P. , Johnson Lincoln V.
Published: February 2005

Previous studies have identified a glycoprotein (GP215) that is secreted by the murine oviductal epithelium and subsequently becomes sequestered within the perivitelline space of oocytes and developing embryos (Kapur and Johnson, Dev. Biol. 112:89–93, 1985; J. Exp. Zool. 238:249–260, 1986). The ultrastructural localizations of GP215 in the perivitelline space of ovulated oocytes and in the oviductal epithelium are described here. The glycoprotein is shown to be associated with a morphologically discrete extracellular matrix that provides a unique microenvironment for fertilization and early developmental events. In addition, putative secretory granules that contain this glycoprotein are observed in specific segments of the murine oviductal epthelium, suggesting regional differences in the composition of oviductal secretions.
Construction of a flexible airway model for teaching
Authors: Wang P. M. , Kraman Steve S.
Published: February 2005

A method of producing flexible and strong models of canine airways is described. The animal's lungs are dried in inflation by using compressed air and then filled with silicone sealer. After this compound dries, the lung tissue is removed by corrosion by using NAOH. The result is a rugged, flexible, and anatomically faithful model of canine airways that is suitable for use in teaching.
Tracheobronchial epithelium of the sheep: IV. Lectin histochemical characterization of secretory epithelial cells
Authors: Mariassy Andrew T. , Plopper Charles G. , George Judith A. St. , Wilson Dennis W.
Published: February 2005

Conventional histochemical characterization of the mucus secretory apparatus is often difficult to reconcile with the biochemical analysis of respiratory secretions. This study was designed to examine the secretory glycoconjugates in airways using lectins with biochemically defined affinities for main sugar residues of mucus. We used five biotinylated lectins—DBA (Dolichos biflorus) and SBA (Glycine max) for N‐acetyl galactosamine (gaINAc), BSAI (Bandeiraea simplicifolia) and PNA (Arachis hypogea) for galactose (gal), UEA I (Ulex europeus)—for detection of fucose (fuc) in HgCl2 ‐fixed, paraffin‐embedded, serially sectioned trachea, lobar and segmental bronchi and bronchioles of nine sheep. Lectins selectively localized the carbohydrate residues in lumminal secretions, on epithelial cell surfaces, and in secretory cells. Inp proximal airways, the major carbohydrate residues in luminal secretions, cell surfaces, goblet cells, and glands were fuc and gal‐NAc. PNA reacted mainly with apical granules of < 10% of goblet cells, and gal residues were only detected in some of the mucous cells and on basolateral cell surfaces. Distal airways contained sparse secretion in the lumen, mucous cells containde weakly reactive fuc and gal‐NAc, and the epithelial surfaces of Clara cells contained gal. Sugars abundant in the airway secretions were also the major component of cells in glands. We conclude that there is a correlation between specific sugar residues in secretory cells, glycocalyx, and luminal secretions in proximal and distal airways. This suggests that lectins may be used to obtain information about airway secretory cell composition from respiratory secretions.
Characterization of prenatal growth and development in the crab‐eating macaque (macaca fascicularis) by ultrasound
Authors: Tarantal Alice F. , Hendrickx Andrew G.
Published: February 2005

Diagnostic ultrasound is a valuable tool for the examination of various anatomical structures in vivo. Improvements in technology have increased its effectiveness and provided a noninvasive method for the in utero observation of a variety of structural and functional events. Ultrasound is utilized in our laboratory to monitor a variety of studies during embryonic and fetal development. Basic to these evaluations is the ability to assess normal growth and development. The cynomolgus, or crab‐eating macaque (Macaca fascicularis), has been observed in utero by ultrasound from early gestation to term. The earliest detection of implantation is by the identification of a developing gestational sac (GS), which may be visualized on gestational day (GD) 14–15. Positive identification of the GS on GD 16–18 and appearance of the embryo, yolk sac, and cardiac motion on GD 21–25 confirms pregnancy. Once the embryo is evident, measurements of the greatest length (GL) may be used to assess normal growth or to aid in the prediction of gestational age. During the fetal period, a variety of growth parameters aid in fetal evaluation. The gender of the fetus can be accurately identified as early as GD 70–75. An assessment of viability and condition can be determined by the observation of embryonic and fetal heart rates and gross body movement.
Inflammation of rat molar pulp and periodontium causes increased calcitonin gene‐related peptide and axonal sprouting
Authors: Kimberly C. L. , Byers M. R.
Published: February 2005

We have studied the response of nerve fibers containing calcitonin gene‐related peptide immunoreactivity (CGRP‐IR) to inflammation using a rat dental experimental system. Inflammation was induced by drilling tooth cusps to create pulpal exposures; the induced pulpitis and subsequent periapical lesions were studied 1–35 days later using standard CGRP immunohistochemistry and the avidinbiotin peroxidase method. The injury and resulting inflammation caused a disruption of CGRP‐IR nerve fiber location and arborization that varied depending on whether the initial injury was limited to the pulp tip or extended throughout the pulp horn. At shorter survival periods (24 hr, 3 days) nerve fibers were either decreased or bundled into the center of the pulp with sprouting along the wound border. At 6 days necrosis and acute inflammation had advanced to varying degrees, and CGRP‐IR fibers were extensively sprouted in the surviving pulp; the pulp also stained specifically for CGRP within 1–2 mm of the infalmed tissue at 6 days. At 35 days, we found total pulp necrosis in most teeth and the development of periapical bone loss, granulomatous tissue, and periapical abscesses. There was also an extensive increase in CGRP‐IR nerve fibers in the tissues surrounding sites of severe periodontal inflammation and necrosis. In some cases, macrophage‐like cells staining specifically for CGRP were near the abscesses. The results show important interactions between peptidergic nerve fibers and inflammatory cells, and are discussed in terms of the role of nerve fibers containing CGRP in neurogenic inflammation, mechanisms for intensification of CGRP immunoreactivity in affected fibers or neighboring cells, and implications for chronic inflammatory conditions, dental pain, and anesthesia.
Mitochondrial size and shape in equine skeletal muscle: A three‐dimensional reconstruction study
Authors: Kayar S. R. , Hoppeler H. , Mermod L. , Weibel E. R.
Published: February 2005

Individual mitochondria were reconstructed from ultrathin serial sections of selected muscle fibers in the M. semitendinosus of a horse, over a length of nearly two sarcomeres. Mitochondria were found to be highly variable, with size and complexity of single mitochondria increasing with the fractional part of a fiber occupied by mitochondria. In fibers with a mitochondrial volume density of less than 4%, corresponding to the mitochondrial content of fast‐twitch glycolytic fibers, mitochondria were generally rather simple cylindrical shapes, oriented parallel to the myofibrils. In fibers with a mitochondrial volume density of more than 7%, corresponding to the mitochondrial content of slow‐oxidative or fast‐oxidative glycolytic fibers, mitochondria were generally cylindrical at the A‐band and Z‐plate level of the muscle sarcomeres. However, these mitochondria often had transverse extensions or interconnections that occurred at the I‐band level. Volumes of individual mitochondria ranged from as small as a few thousandths of a μm3 up to several μm3 for the incompletely reconstructed portions of the largest mitochondria. Mitochondrial profiles that one would classify from single sections as subsarcolemmal were found to interconnect with other profiles deeper within the fiber. This suggests that it is unlikely that subsarcolemmal and interfibrillar mitochondria are two structurally distinct populations. However, we found no evidence of a reticulum completely interlinking all mitochondrial material in a muscle fiber.
Membrane systems of guinea pig myocardium: Ultrastructure and morphometric studies
Authors: Forbes M. S. , van Niel E. E.
Published: February 2005

The structure and quantitative contribution of membrane systems (transverse‐axal tubular system [TATS] and sarcoplasmic reticulum [SR]) have been investigated in the heart of the adult guinea pig. Although previous quantitative studies have been made of guinea pig myocardium, this is the first such study that has utilized tissue in which membrane system elements were clearly identified by selective staining (in this case by the osmium‐ferrocyanide [OsFeCN] postfixation method). Both membrane systems are highly developed in ventricular cells, but a TATS is essentially absent from atrial myocytes. The ventricular TATS consists principally of large‐bore elements which may be oriented transversely, axially, or obliquely, making numerous anastomoses with one another to form a highly interconnected system of extracellular spaces that penetrate to all myoplasmic depths of the ventricular cell. The cell coat that lines the lumina of these tubules is structured, containing fibrillar structures that run along the length of the tubule. The volume fraction (Vv) of the ventricular TATS is low (2.5–3.2%), in consideration of the qualitative prominence of the TATS in these cells.

The relative total population of sarcoplasmic reticulum is higher in the atria (Vv of 10–11%) than in the ventricles (Vv of ca. 8%). In all guinea pig myocytes, several major structural divisions of SR can be discerned, which include network SR, junctional SR, corbular SR, and cisternal SR. Junctional SR (J‐SR) in the atrial cells is limited almost exclusively to peripheral saccules of junctional SR (PJSR), whereas both interior J‐SR and PJSR are present in the ventricle. Two distinct morphological types of PJSR appear in atrial cells, including both flattened and distended saccules, the latter resembling PJSR of lower vertebrate heart. Spheroidal bodies of SR with opaque contents (corbular SR) are prominent at or near Z‐line levels of the sarcomeres of atrial and ventricular cells. Cisternal SR is likely a subset of network SR, but some examples appear related to rough endoplasmic reticulum. An overall impression obtained from this study is that guinea pig atria are composed of structurally primitive cells, whereas the ventricular cardiac muscle cells are more highly developed entities.

Freeze‐fracture replicas were prepared by Ms. Bonnie Sheppard of the Central Electron Microscope Facility of the University of Virginia School of Medicine. We are grateful as well to Ms. Lisa Kremer for her skillful preparation of the electron micrographs used for the stereology studies reported in this communication. Special thanks go to Mr. Guenter Lamprecht of Carl Zeiss, Inc., Thornwood, New York, for providing access to the Zeiss EM 902 instrument, and to Mr. Jean‐Marc Theler (Department of Physiology, University of Virginia School of Medicine) for valuable discussions concerning aspects of this research.
Human abductor pollicis brevis muscle “divisions” and the nerve hila
Authors: Simard Thérèse , Roberge Jean
Published: February 2005

The interpretation of neuromuscular impairement may be aided by an analysis of functional anatomic factors. The anatomy of the abductor pollicis brevis (APB), a muscle used for skilled movements, was investigated in 19 embalmed hands, and the muscular divisions joining the common tendon at different sites were reproduced on clear vinyl sheets. The median nerve pathway to thenar muscles was followed to where it divides to the APB nerve and to the sites of the main terminal hila. Transverse (x) and longitudinal (y) muscle axes were established with the aid of landmarks to reproduce the nerve pathway on the skin surface. In the rather thick APB, three groups of six muscular heterogeneous divisions were regularly present. The dorsal aponeurotic expansion of the thumb receives the first group. The second group forms a continuous vertical line from the base to the body of the first phalanx. The outside site of its lateral tubercle takes the central tendon from the penniform third group. Hence, a reverse figure‐seven distal insertion can be observed. The deepest medial (V2) and the most superficial lateral (V3) divisions had the highest mean diameters. The APB nerve fall between V2 and V2′ and its line of projection supplied a guideline to establis an x axis at the proximal one‐third of the muscle. The nerve hila plotted in relation to the x‐y axes revealed a mode of location. The classical description of a thin APB muscle, made up of two bellies of parallel fibers seems incorrect. The APB nerve is not found on the deep aspect of the muscle as stated earlier, but within the muscle. The well‐innervated muscular divisions point to the possibility of their individual use. The APB neuromuscular projection to the skin should allow more accureate fundamental EMG studies of the thumb and therefore provide a basis for more effective treatment in cases of impaired APB.
Granular epithelioid cells of the kidneys in salmon adapted to fresh‐ and seawater
Authors: Christensen J. A. , Mikeler E. , Bohle A.
Published: February 2005

The occurrence of granular epithelioid cells in the kidney arterial vessels was studied in one‐and two‐year‐old Atlantic salmon during the physiological fresh‐ and seawater periods. The purpose of this study was to make long‐term comparison on the morphology of the renin angiotensin system in the same fish species. One‐year‐old salmon living in freshwater had a statistically significant higher number of granular epithelioid cells (39.9 ± 8.3/mm arterial vessel) than the two‐year‐old fish living in seawater (29.8 ± 5.2/mm arterial vessel, P < 0.00001). There was also a significant difference from month to month between the groups (P < 0.05), but not within the groups (P > 0.07 freshwate, P < 0.3 seawater). With the electron microscope the granules were found evenly distributed within the cytoplasm. They were of high electron density and lined by a single membrane. The granules were composed of a finely granular material. The recorded data on length and weight showed that all fish ate and developed normally. From our results and the available literature, we conclude that in primitive vertebrates, the renin angiotensin system is primarily involved in renal circulation, with vasoconstriction on the afferent side of glomerulus.
An electron microscopic study of cells with steroid‐secreting morphology in the paraaortic lymph node of the hamster
Authors: Kimura Michio , Tohya Kazuo , Kuroiwa Kyo‐Ichi
Published: February 2005

Clusterd cells with steroid‐secreting morphology (SH), located within the paraaortic lymph node (PLN) capsules of normal and pregnant female golden hemsters, were examined by light and electron microscopy. Hydroxysteroid dehydrogenase (HD) activity of the SH cell cluster also was examined by histochemical techniques. The cluster was composed of mostly packed SH cells and surrounding mesenchymal cells. Individual SH cells posessed prominent smooth endoplasmic reticulum, well‐development Golgi complexes, some lipid droplets, and numerous mitochondria containing tubulovesicular cristae common to mammalian SH cells. Intermediate‐type junctions were often observed between SH cells. The same SH cells were rarely detected in the subcapsular sinus and in the cortical parenchyma of the PLN. Early oophorectomy of the hanster resulted in cytopolasmic degeneration of the SH cell at day 5 after the operation. On the other hand, normal adult male hamsters possessed similar PLNs, but mo SH cells were recoginzed in the nodos. The present hiustochemical preparation of normal PLNs revealed moderate‐to‐strong HD activity, probably associated with SH cell clusters, in the limited regions of the capsules.

Based on the present ultrastructural and histochemical findings, it is proposed that the SH cell cluster consists of steroid producing cells.
Primary sity immune response in popliteal lymph nodes and spleen of mice after subcutaneous immunization with thymus‐dependent or thymus‐independent (type 1 and 2) antigens
Authors: Delemarre F. G. A. , Claassen E. , Van Rooijen N.
Published: February 2005

Mice were immunized subcutaneously with thymus‐independent (TI)‐type 1 antigen trinitrophenylated lipopolysacccgaride (TNP‐LPS), TI‐type 2 antigen TNP‐Ficoll or thymus‐dependnt (TD) antien TNP‐keyhole limpet haenicyanin (TNP‐KLH) in order to study the primary in situ immune response in popliteal lymph nodes (PLN) and spleen. The spleen responded more rapidly in developin specific antibody‐forming cells (AFC) than the lymph nodes did, in spite of the fact that antigens reach the spleen only after pasing several lymplh several lymph node stations. This difference between lymph nodes and spleen in development AFC was partivularly significant with respect to the responses to the responses to TI (both type 1 and type 2) antigens. No differences in the distribyution of specific AFC in PLN and spleen were oseved after immunization with TI and TD antigens. Results are discussed with respect to the relative contributions of lymph nodes and spleen to immune responses to antigens injected subcutaneously.
Differentiation of interstistial cells and stromal proteins in the secondary septum of early postnatal rat: Effect of maternal chronic exposure to whole cigarette smoke
Authors: Vidić Branislav , Ujević Neven , Shabahang Mohsen M. , van de Zande Frederike
Published: February 2005

The intention of this investigation was to ascertain the effect of maternal exposure to cigarette smoke on the early postnatal morphogenesis of pulmonary interstitum in offspring. Female rats were chronically exposed to whole cigraette smoke. Offspring of these and control animals were sacrificed at postnatal day 15, and their tissues were prepared for quantitative and qualitative analyses. Results indicate a diminished quantitative representaion of parenchymal tissue (P <0.01) and a slower pace of secondary septal growth (P <0.07) in the experimental lung. Furthermore, a greater cellular volume density (P <0.0002) was ascertained for the experimental septal inerstitium. There was proportionately less of elastin substances (P < 0.009), collagen together with basal laminae (P < 0.0008), and nonfibrillar, amorphous matrix (P < 0.02) in the experimental extracellular stroma. Fribrillar collagen and nonfibrillar matrix were represented quantitatively 6.3 times more in the experimental extracellular interstitum than elastin, whereas that ratio for the control tissue was only 4.2. Most experimental interstitial cells (80%) contained numerous lipid globules, which, in contrast, were only occasionally present in control cells (7.3%). Experimental cells, consequently, possessed a larger cross‐sectional diameter and a smaller nucleus‐to‐cytoplasm volume ratio than control cells. These divergent developmental patterns are possibly suggestive of a delayed differentiation of interstitial cells and a modified production to degradation balance of stromal proteins in offspring of animals chronically exposed to whole cigarette smoke.
Diameters and cross‐sectional areas of branches in the human pulmonary arterial tree
Authors: Horsfield Keith , Woldenberg Michael J.
Published: February 2005

Measurements were made of the diameters of the three branches meeting at each of 1,937 difurcations in the pulmonary arterial tree, using resin casts from two fully inflated human lungs. Cross‐sectional areas of the parent branch and of the daughter branches were calculated and plotted on a log‐log plot, which showed that mean cross‐sectional area increases in a constant proportion of 1.0879 at bifurcations. The mean value of the ratio of daughte branch diameters at bifurcations was 0.7849. The mean value of the exponent z in the equation flow = k (diameterz) was found to be 2.3 ± 0.1, which is equal to the optimal value for minimizing power and metabolic costs for fully developed turbulent flow. Although Reynolds number may exceed 2,000 in the larger branches of the pulmonary artery, turbulent flow probably does not occur, and in the peripheral branches Reynolds number is always low, excluding turbulent flow in these branches. This finding seems to be incompatible with the observed value of z. A possible explanation may be that other factors may need to be taken into account when calculating the theoretical optimum value of z for minimum power dissipation, such as the relatively short branches and the disturbances of flow occurring at bifurcations. Alternatively, higher arterial diameters reduce acceleration of the blood during systole, reduce turbulent flow, and increase the reservoir function of the larger arteries. These higher diameters result in a lower value of z.
Progesterone secretion and mitochondrial size of aging porcine corpora lutea
Authors: Adair Valerie , Stromer Marvin H. , Anderson Lloyd L.
Published: February 2005

A functional dependency between the nongravid uterus and the ovaries is essential to luteolysis and the return to estrus in the pig. After mating of gilts, the corpora lutea develop, and they are required for the maintenance of pregnancy to a normal duration of about 114 days. Hysterectomy of luteal phase (day 6) nongravid gilts results in persistence of the corpora lutea to 150 days. We report that these corpora secrete greater quantities (P < 0.025) of progesterone than during the later half of gestation (days 54–108). Although aging corpora lutea remain functional for at least an additional 35 days, an abrupt reduction by half in progesterone secretion (16 ng/ml) occurs about day 114 in hysterectomized gilts that coincides with the prepartum decrease to basal serum levels (<0.5 ng/ml) at parturition (day 114) and during lactation. Aging corpora lutea remain large (averaging > 450 mg) on days 124 and 136 in hysterectomized gilts, whereas they regress (averaging < 75mg) in the lactating dams. Mitochondria continue to increase in size in aging corpora lutea of hysterectomized gilts until day 136; in contrast, they decrease during the postpartum period in lactating dams. A precisely timed signal, possibly of ovarian origin or form the CNS and pituitary gland, entrains in hysterectomized and pregnant pigs at day 113 that results in marked shifts in relaxin and progesterone secretion. Progesterone secretion and mitochondrial features suggest that procine corpora lutea seem genetically controlled and are preprogrammed at estrus for the duration of pregnancy, regardless of the presence of conceptuses or absence of the uterus.
Delayed muscle fiber transformation after foreign‐reinnervation of excessive muscle tissue
Authors: Käser Lorenzo , Müntener Markus
Published: February 2005

Follwing partial deneration motor units can increase (by selfreinnervation) as much as four to five times their normal size. To investigate the still unknown quantitative reinnervation capacity of a motor nerve in the case of foreign‐reinnervation, in adult male rats the denervated sternomstoid muscle was either self‐reinervated by its original nerve or foreign‐reinnervation by the omohyoid nerve, which had to reinnevate the three times the amount of muscle fibers and six times the amount of muscle mass. After survival times of 7, 8, 9, or 10 months, nerves and muscles were investigated histochemically and immunohistochemically. The omohyoid nerve could fully reinnervate the sternomastoid muscle, but at 7 and 8 months this muscle still revealed nearly the same proportions of IIA and IIB fibers as were seen in the self‐reinnervated sternomastoid at all stages. However, in the following 2 months a shift of the fiber pattern toward that of the normal omohyoid was observed, as evidenced by a strong increase in type IIB fibers (from 24% to 62%), at the expense of type IIA fibers. These findings are in contrast to those after foreign (cross) reinnervation of leg muscles where the fiber transfor mation (according to the foreign motor input) occurs in parallel with the reinnervation process during the first 2‐3 months. The delayed fiber transformation observed could be the consequence of the highly enlarged peripheral field of the omohyoid motoneuron pool or could merely reflect a general difference between limb and neck muscles. Whatever the case may be, in the present experiments the afferent input, which is not fully restored until 9 months, could play a crucial role in contrast to limb muscles, where the successful motor reinnervation takes place in the absence of sensory activity.
Coordinated regulation of endothelial and fibroblast cell proliferation and matrix synthesis in periodontal ligament adjacent to appositional and resorptive bone surfaces
Authors: Nemeth Endre , McCulloch Christopher A. G. , MeLcher Antony H.
Published: February 2005

Little is known about the remodeling of blood vessels and soft connective tissue or the proliferation of endothelial cells in the periodontal ligament (PL) of teeth undergoing physiological drift. To determine whether there is evidence for coordinated regulation of endothelial cell and fibroblast proliferation and matrix synthesis in sites within the PL adjacent to bone‐appositional (A) and bone‐resorptive (R) surfaces, the PL in mouse mandibular molar was subdivided into A and R sectors on the basis of 3H‐proline incorporation into alveolar bone. Computer‐assisted morphometry of radioautographs showed that the number and area of blood vessels were similar in A and R sectors. Proliferation of endothelial cells and fibroblasts was assessed from radioautographs prepared from mice continuously labeled with 3H‐thymidine at times between 2 and 60 days. Significantly more labeled endothelial cells (P < .001) and fibroblasts (P < .05) were seen in the A sector. The percent of labeled endothelial cells and the percent of labeled fibroblasts increased linearly to 25 days and then formed a plateau. The rate of increase of labeled fibroblasts was higher in the A sector than in the R sector (P < .025). In addition, 3H‐proline grain counts over extracellular matrix were significantly higher in the appositional sector than in the resorptive sector (P < .025). These data suggest first that PL endothelial cell populations are in steady state despite significant cell turnover, and second, that the remodelling of blood vessels and extracellular matrix, as well as the turnover of fibroblasts and endothelial cells, occurs at a more rapid rate in A sectors of the PL than in R sectors and appear to be coordinately regulated by factors associated with the phenomenon of tooth drift.
Initiation and duration of myogenic precursor cell replication in transplants of intact skeletal muscles: An autoradiographic study in mice
Authors: Roberts Peter , McGeachie John K. , Grounds Miranda D. , Smith Ellena R.
Published: February 2005

Skeletal muscle fibers are capable of regeneration following ischemia, traumatic injury, or transplantation. Although the time course of the regenerative process has been studied in detail histologically, little is known about the time of activation of myogenic precursor cells which are primarily responsible for muscle regeneration.

This study was designed to determine the initiation peak proliferative activity, and cessation times of muscle precursor replication in small skeletal muscle transplants. Forty‐eight young male BALB/c mice had the extensor digitorum longus muscles of both hind legs autotransplanted to a different site in the same leg. At various time intervals after transplantation (from 24 hours to 14 days), mice were injected once with a small dose of tritiated thymidine in order to label proliferating myogenic precursor cells.

The transplants were allowed to regenerate for 14 days, before being removed, processed for autoradiography, and analysed by light microscopy. The presence of labelled myotube nuclei in regenerated transplants showed that myogenic precursors had been replicating at the time of tritiated thymidine injection. Myogenic precursor replication was initated late on the second day (42–48 hours) after transplantation, peaked after 6 days, and was complete within 10 days.
Distribution of extracellular matrix in the migratory pathway of avian primordial germ cells
Authors: Urven Lance E. , Abbott Ursula K. , Erickson Carol A.
Published: February 2005

The apperance and distribution of extracellular matrix (ECM) was documented along the migratory route of chicken primordial germ cells (PGCs). The antimouse embryonal carcinoma cell antibody, EMA‐1, was used to label PGCs (Urven et al.: Development 103:299–304, 1988). Antibodies against laminin, fibronectin, chondroitin sulfate proteoglycan and collagen type IV were used to label extracellular matrix components. When the PGCs emerged from the epiblast, all four ECM molecules were restricted principally to the basement membrane of the epiblast. Chondroitin sulfate was also located between hypoblast cells during this period. In late germinal crescent stages, when the PGCs entered the lumina of blood vessels, the same ECM molecules were more widespread in the mesoderm and in extracellular spaces. In addition, laminin and collagen type IV were identified on lateral surfaces of ectodermal cells at this stage. When the germ cells moved through the mesenchyme into the germinal ridge, the ECM molecules were found around mesenchymal cells, and, in the cases of laminin, fibronectin and collagen type IV, in the basement membranes of the germinal ridge epithelia. Because the appearance of these ECM components is temporally and spatially correlated with the movement of PGCs, we suggest that early PGC migration may depend on their timely appearance.
Comparison of 3H‐galactose and 3H‐glucose as precursors of hepatic glycogen in control‐fed rats
Authors: Michaels John E. , Garfield Sanford A. , Hung Julia T. , Cardell Robert R.
Published: February 2005

Labeling of hepatic glycogen derived from 3H‐galactose and 3H‐glucose was compared shortly after intravenous injection in control‐fed rats. The rats were allowed to accumulate 5‐8% glycogen prior to receiving label. Fifteen minutes to 2 hours after labeling, liver was excised and processed for routine light (LM) and electron microscopic (EM) radioautography (RAG) or biochemical analysis. After injection of 3H‐galactose, LM‐RAGs revealed that the percentage of heavily labeled hepatocytes increased from 37% after 15 minutes to 68% after 1 hour but showed no further increase after 2 hours. α‐Amylase treatment removed most glycogen and incorporated label; thus few silver grains were observed, indicating little incorporation of label except into glycogen. EM‐RAGs demonstrated that most label occurred where glycogen was located. Biochemical analysis showed initially a high blood level of label that rapidly plateaued at a reduced level by 5 minutes. Concomitantly, glycogen labeling determined by liquid scintillation counting reflected the increases observed in the RAGs. After injection of 3H‐glucose, LM‐RAGs revealed that only 12% of the hepatocytes were heavily labeled at 1 hour and 20% at 2 hours. In tissue treated with α‐amylase, glycogen was depleted and label was close to background level at each interval observed. EM‐RAGs showed most grains associated with glycogen deposits. Biochemically, blood levels of label persisted at a high level for 30 minutes and tissue levels increased slowly over the 2‐hour period. This study shows that incorporation from 3H‐galactose was more rapid than incorporation of 3H‐glucose; however, label derived from both carbohydrates appeared to be incorporated mainly into glycogen.
Calcium transport during mineralization
Authors: Bawden James W.
Published: February 2005

The translocation of calcium from the extracellular fluid compartment into the mineralizing matrix during hard tissue formation is not well understood. There are two general means by which such calcium movement may occur: (1) diffusion through the pericellular space, or (2) transcellular transport. Cementum and bone are difficult tissues in which to study the system and little is known about the mechanisms involved. Dentin offers certain advantages for study and it appears that calcium movement into the mineralizing matrix is by trans‐cellular transport. Information concerning the transport mechanism is meager. Enamel is more easily explored. The apparent existence of intercellular junctions tight to calcium in the ameloblast layer at all stages of enamel formation indicates that calcium movement occurs by transcellular transport. Based on published findings, a hypothesis concerning mechanisms of transcellular transport may be advanced. It is proposed that the relatively low level of calcium transport through secretory ameloblasts occurs without direct involvement of a calcium binding protein. During the maturation stage, when calcium influx to the matrix is greatly increased, a calcium binding protein (9 kd) appears and facilitates transport while preventing unphysiologic increases in the cytosolic free calcium ion concentration. Differences in the calcium ion concentrations of extracellular fluid and enamel matrix fluid appear to be critical to the influx of calcium across the proximal cell membrane and the efflux of calcium across the distal cell membrane.
Studies on the vasculogenesis in rat cerebral cortex
Authors: Mato Masao , Ookawara Shigeo , Namiki Takuo
Published: February 2005

The cerebral cortices are nourished by blood circulating through a capillary network branching from parent arteries. In this paper, vasculogenesis of the cerebral cortices in developing rats (11–18 days after birth) was studied by light and electron microscopy after intravenous administration of horseradish peroxidase (HRP).

In the first phase of vasculogenesis, tentacles grew out from the distal end of the vascular cord (tip cells), and in the second phase, they extended to the afferent blood vessel. The reaction product of HRP was distributed not only in the primitive vascular lumen, but also in the peripheral extravascular space of the vascular cord. Most tentacles were free from reaction product, but, in some cases where reaction product was detected, the intercellular spaces had spread into the tip cells and reached the root of the tentacles.

After the tentacles contacted the afferent vascular cord, the two vascular cords approached and fused with each other. Blood serum was able to circulate between the two vascular cords via the irregular interstices formed among the endothelial cells, cytoplasmic processes, and tentacles. Later, the primitive vascular lumen developed to a sufficient size to allow for the circulation of blood cells. The sequential events in the process of fusion between two vascular cords are illustrated.

The following two points were also noticed in this study: (1) during cerebral vasculogenesis, degeneration and vacuolization in primitive endothelial cells occurred only in some of the serial sections and did not play a significant role in the formation of vascular lumen, and (2) cerebral pericytal macrophages (CPM) (classified as fluorescent granular perithelial cells by the authors) appeared close to the vascular cord, although the biological meaning of it remained unknown in the present investigation.
Neuromuscular organization of the pectoralis (pars thoracicus) of the pigeon (Columba livia): Implications for motor control
Authors: Kaplan S. R. , Goslow G. E.
Published: February 2005

The pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen. An additional three animals were used to analyze the morphology, distribution, and histochemical profiles of the muscle fibers in the SB and TB subregions. Fibers were characterized on the basis of their reactions for myofibrillar adenosine triphosphates (alkaline and acid preincubation) and reduced nicotinamide adenine dinucleotide diaphorase (NADH‐D). The SB is primarily innervated by the rostral nerve branch and the TB by the caudal nerve branch. For two‐thirds of the muscle's length, the SB is separated from the TB by an aponeurosis, the membrana intermuscularis (MI). SB and TB fibers located posteroventral to the caudal margin of the MI are innervated variously by both nerves. Two populations of fibers were recognized, distinguishable primarily by (1) fiber diameter and (2) density of the NADH‐D reaction product. Compared to the TB, the SB possesses a higher average percentage of large fibers. Within the SB but not the TB the percentage of large fibers increases from deep to superficial. These data support our previous findings that the pars thoracicus of the pigeon is partitioned into at least two functional subunits, each with a potential for independent action on the wing during flight.
Angiogenesis in the postovulatory primate endometrium: The coiled arteriolar system
Authors: Kaiserman‐Abramof Ita R. , Padykula Helen A.
Published: February 2005

The postovulatory period in the primate endometrium of the menstrual cycle is characterized by rapid growth of the coiled arterioles. A great variety of developing microvascular components occurs among a well‐differentiated microvasculature of coiled arterioles, capillaries, and venules. Endometrial biopsies were obtained by hysterotomy during progesterone dominance at 5, 6, 7, 10, 12, and 14 days following the peak of the estrogen surge as determined by serum radioimmunoassay. Arteriolar ultrastructural differentiation is remarkably similar on each of these days.

Ultrastructural evidence of elastogenesis in the extracellular matrix adjacent to certain endothelial tubes provides the initial sign of coiled arteriolar formation. The cellular primordia of the tunica intima and media are identified by spatial location and glycogen storage in smooth muscle cells. Endothelial projections span the incipient internal elastic membrane to make contact with the surfaces of the innermost vascular smooth muscle cells.

Subsequent arteriolar differentiation centers on formation of a muscular media composed of 1 or 2 muscle layers separated by a spiraling lamellar elastic matrix that appears initially between the endothelial tube and the first muscle layer. Vascular smooth muscle cells are highly branched and linked across the elastic matrix by surface contacts. Definitive coiled arterioles consist of interlinked endothelial and smooth muscle cells within a thick, spiraling elastic matrix that provides flexibility for rapid changes in shape. Progressive differentiation of coiled arterioles continues up to the premenstrual stage. This abundant angiogenesis may reflect preparation and maintenance of a suitable uterine environment for the possibility of implantation and pregnancy during each menstrual cycle.
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

The 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

The 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

In 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

On 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.