bluuebunny/crossref_metadata_2025 huggingface dataset:
Annulate lamellae‐soleplate nuclei associations in skeletal muscle fibers of rats during chronic high‐dose exposure to neostigmine
Authors: Kawabuchi Masaru , Osame Mitsuhiro , Aika Yusuke , Kanaseki Takeshi
Published: February 2005

To investigate annulate lamellae (AL) with nuclear changes, ultrastructural time course studies were done of the reversible end‐plate myopathy in the soleus muscles of rats exposed chronically to a high dose of the anticholinesterase drug neostigmine. At the earliest stage (2 hours) in which severe subjunctional damage involving a nuclear lesion (nuclear pyknosis) was prominent, AL profiles were undetectable. At the intermediate stage (7, 21 days), in which the subjunctional organelles tended to cluster and nuclear pyknosis often accompanied degenerative features, most AL laid near the surface of the abnormal nuclei, where there were signs of elimination or formation of pores, as well as a progression of changes leading to the loss of pores. At the late stage (56 days), in which muscle repair was nearly completed and euchromatic nuclei usually were found, there was a concomitant enhanced formation of false nuclear inclusions and of the AL profiles in these sites.

Pores are packed on nuclear envelopes, which detach themselves from the nucleus and take the same profile as AL. This phenomenon can be envisioned not only in the euchromatic but also in the abnormal (pyknotic or degenerated) nuclei. Following nuclear reconstitution, the nuclear envelope folding is accelerated to induce the usual pattern of AL organization, i.e., budding from the invaginated nuclear envelope.
Endocardial cell arrangement: Role of hemodynamics
Authors: Icardo Jose M.
Published: February 2005

This paper demonstrates the presence of areas where endocardial cells are aligned with the blood flow in three distinct regions of the embryonic chick heart: on the inferior border of the growing septum primum, on the upper wall of the primitive ventricle above the developing interventricular septum, and on the part of the atrial floor that funnels into the atrioventricular canal. While orientation in the first two areas is transitory, the number of cells aligned with the blood flow in the atrial floor increases from days 3 to 5 of incubation. It is suggested that shear stress induces endocardial cell orientation in these areas. To further explore the role of hemodynamics in endocardial cell arrangement, the left of the vitelline vein was severed at stages 13–14. This resulted in abnormal development of the vitelline venous system. Examination of experimental embryos at 5 days of age revealed the presence of a distinct area of endocardial cell orientation in the dorsal wall of the right atrium, near the opening of the sinus venosus. Changes in the venous return to the atria may modify flow patterns, thus inducing endocardial cell orientation. This experimental procedure may be a useful model not only for exploring the effects of hemodynamics upon the endocardium, but also for investigating other aspects of heart development under altered hemodynamic conditions, without manipulating any portion of the embryonic heart.
Reactivity of rat and rabbit intrafusal fibers with monoclonal antibodies directed against myosin heavy chains
Authors: Maier Alfred , Zak Radovan
Published: February 2005

Serial cross and longitudinal sections from the intracapsular portions of intrafusal fibers of rat and rabbit tibialis anterior muscles were examined by fluorescence microscopy with a library of monoclonal antibodies directed against different epitopes on myosin heavy chains. Intrafusal fiber types were identified with the histochemical reactions for acid‐stable and alkali‐stable actomyosin ATPase. Three antibodies, known to react with avian heart and slow‐tonic myosins, produced fluorescent staining in intrafusal fibers. Nuclear bag2 fibers reacted with all three antibodies, chain fibers with two, and nuclear bag1 fibers with only one. These results indicate that in rat and rabbit tibialis anterior muscle spindles nuclear bag2 fibers and chain fibers contain more than one myosin isoform. They also demonstrate that, in addition to the histochemical actomysin ATPase reaction, nuclear chain fibers and the two types of nuclear bag fibers can be identified by the selective reactivities of their myosin heavy chains.
Effect of adriamycin on hamster molar tooth development in vitro: 1. Morphological changes
Authors: Karim A. C. , Woltgens J. H. M. , Bervoets Th. J. M. , Lyaruu D. M. , Bronckers A. L. J. J.
Published: February 2005

The effect of adriamycin (1 mg/liter) on the development of the golden hamster 3‐day‐old second maxillary molars (M2) was investigated in vitro. Exposure of the molars to 1 mg/liter adriamycin during the first 2 hours of culture produced smaller teeth 3–7 days later, as determined by measurements of dry weights and by histological observations. Higher doses caused severe necrosis. The more differentiated pulp fibroblasts showed osteodentin formation 3 days after treatment with adriamycin (1 mg/liter), while the more immature ones underwent necrosis. The phenotypic changes brought on by the drug were permanent, and osteodentin continued to be formed throughout the course of this study. In addition the cervical loop region was inhibited from growing, while the production of the matrices of enamel and dentin appeared to be increased at 3 and 5 days after treatment. Electron microscopy of the forming osteodentin matrix revealed a random arrangement of banded collagen fibers during the early stage of osteodentin formation. As more matrix was formed, the collagen became quite compact and appeared quite similar to dentin. Finally, matrix vesicles were found among the collagenous matrix that was not yet mineralized. With the exception of the increased production of enamel and dentin, these in vitro results confirmed those earlier in vivo studies on the effect of adriamycin on rat incisor tooth.
Ultrastructural and cytochemical study of elastic fibers in the ventral aorta of a teleost, Anguilla japonica
Authors: Isokawa Keitaro , Takagi Minoru , Toda Yoshihisa
Published: February 2005

Previous studies have revealed that amorphous elastin and microfibrils are structural entities of mammalian elastic fibers. Elastin shows a wide phylogenetic distribution, but the presence of elastin‐associated microfibrils has not been demonstrated in teleost aorta. Thus, we have ultrastructurally and cytochemically examined elastic fibers in the ventral aorta of eel, a teleost, by utilizing routine uranyl acetate and lead double staining, the tannic acid (pH 7.0)—uranyl acetate (TA‐UA) method, elastase en bloc digestion, Thiéry's periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) method, and the horseradish‐peroxidase‐labeled concanavalin A (Con A) method. In the ventral aorta of eel, a little ultrastructural difference between elastic fibers in the intima and media and those in the adventitia was noticed, but in either tunic each elastic fiber was basically composed of a “fibrillar core” and surrounding microfibrils. The fibrillar core was a collection of fibrils which showed a tendency to coalesce with each other, and these constituent fibrils were TA‐UA positive and elastase‐sensitive, representing their nature of elastin. By contrast, microfibrils associated with the fibrillar core were TA‐UA negative and elastase‐resistant, and their glycoproteinaceous nature was demonstrated by PA‐TCH‐SP and Con A methods. Thus, this study provides evidence for the presence of elastin‐associated microfibrils in teleost aorta. These results are discussed in relation to the topographical difference of elastic fibers in eel aortic wall.
Intra‐articular synovial folds of thoracolumbar junction zygapophyseal joints
Authors: Singer Kevin P. , Giles Lynton G. F. , Day Robert E.
Published: February 2005

Transverse histological sections from T10‐11, T11‐12, T12‐L1, and L1‐2 zygapophyseal joints were examined in 32 post‐mortem spines, using light microscopy, to record the presence of intra‐articular synovial fold inclusions. In addition, three mid‐joint sections from each joint were photographed using 35 mm colour film. From these slides, linear dimensions of the extent of intraarticular synovial fold projection between the zygapophyseal joints were measured using computer‐aided planimetry. Small, fibrous folds were commonly found at the joint margins extending from the ligamentum flavum and the fibrous joint capsule. Larger, fibro‐adipose synovial folds, projecting between the articular surfaces, were also noted, particularly at T12‐L1 and L1‐2.
Regression of ventricular hypertrophy abolishes cardiocyte vulnerability to acute hypoxia
Authors: Canby Craig A. , Tomanek Robert J.
Published: February 2005

Left ventricular hypertrophy (LVH) secondary to a pressure overload commonly leads to perfusion abnormalities that may limit oxygen delivery to the myocardium and, therefore, result in cardiocyte intracellular damage. We initiated this study to test the hypothesis that the increased vulnerability of the hypertrophied left ventricle to acute hypoxia is minimized when LVH regresses and maximal coronary flow returns to normal. Six‐month‐old spontaneously hypertensive (SHR) and normotensive Wistar‐Kyoto (WKY) rats were divided into control or one of two antihypertensive treatment groups. A 3‐month treatment consisted of captopril (75‐100 mg/kg) or hydralazine (80‐160 mg/L) with hydrochlorothiazide (500 mg/L) added to each therapy. At the conclusion of the treatment period, the rats were administered a 7% O2‐93% N2 gas mixture for 20 minutes to induce acute hypoxic stress during which time hemodynamics, blood gases, and pH were monitored. The heart was then rapidly fixed by vascular perfusion and prepared for electron microscopy. Captopril and hydralazine were equally effective in lowering arterial pressure in both strains, but only captopril was efficacious in reducing heart mass. Hypoxia‐induced changes in hemodynamics, blood gases, and pH were similar in all of the groups; PO2 was decreased by about 70%. The electron micrographs revealed that the hypertrophied left ventricle consistently showed morphologic evidence of hypoxic damage (as indicated by T‐tubular swelling, intracellular edema, and mitochondrial alterations); in contrast hypoxia had little effect on the non‐hypertrophied ventricle. Captopril treatment resulted in a disappearance of the lability to hypoxic damage while hydralazine caused a small reduction in the frequency of hypoxic damage. In conclusion, reversal of hypertension alone had little effect on cardiocyte vulnerability to acute hypoxia, but reversal of hypertension in conjunction with regression of LVH prevented the intracellular damage characteristic of hypoxia. Thus, LVH and its associated maximal perfusion decrement, rather than hypertension per se, underlie cardiocyte vulnerability to hypoxic stress.
Intercellular communication within the rat anterior pituitary Gland. I. Postnatal development and changes after injection of luteinizing hormone‐releasing hormone (LH‐RH) or testosterone
Authors: Soji Tsuyoshi , Yashiro Takashi , Herbert Damon C.
Published: February 2005

The postnatal development of gap junction formation and cell‐to‐cell communication were investigated in male rats from 10 through 40 days of age. These junctions initially appeared between adjacent folliculo‐stellate cells on day 20. Their numbers increased until the animals reached the age of 40 days, when their frequency reached a level that resembled that found in adults. The ontogeny of these junctions was examined in rats treated with luteinizing hormone releasing hormone (LH‐RH) or testosterone. The two hormones were injected for 1 week into rats aged 3, 13, 23, or 33 days. The appearance of gap junctions was accelerated in a similar fashion by LH‐RH and testosterone, with their formation and numbers being advanced by 10 days over that observed in the untreated controls. The results suggest a role for the gonadal steroid hormones in the formation of gap junctions in the rat hypophysis.
Modulation of basal and FSH‐dependent cyclic AMP production in rat seminiferous tubules staged by an improved transillumination technique
Authors: Kangasniemi Marko , Kaipia Antti , Mali Pekka , Toppari Jorma , Huhtaniemi Ilpo , Parvinen Martti
Published: February 2005

The stage‐dependent action of follicle‐stimulating hormone (FSH) in the rat seminiferous epithelium was investigated in microdissected 1 mm tubule segments, where the precise stage of the cycle was identified by a rapid screening method of live cell squash preparations. For distinction of stages I and II and the substages of VII, new criteria were used. The step 16 spermatids with rapid assembly of outer dense fibers leading to marked increase of flagellar thickness were used for distinction of stages I and II. The form and density of the cytoplasmic lobes of step 19 spermatids was used for recognition of substages of VII.

Highest basal production of cyclic AMP (cAMP, measured by radioimmunoassay) was found in stage II of the cycle and stages XIV‐I‐VI had higher values than did stages VII‐XIII. A decline occurred during stage VII and an increase at stage XIV. When stimulated with FSH, highest cAMP secretion was found in stage IV of the cycle; again, stages XIV‐I‐VI had higher values than did other stages. A small but significant (P < .01) stimulation was found at substage VIId. FSH‐stimulated and basal cAMP productions of different stages were compared, highest values were found at stages IV and XIII, and lowest, at stages VIIa‐c and IX of the cycle.

Since the FSH‐dependent cAMP production is confined to Sertoli cells, and the number of these cells is constent per unit length of seminiferous tubules, the Sertoli cells are obviously under a stage‐specific paracrine control by the surrounding spermatogenic cells. Specific steps in cell differentiation, such as spermatogonial proliferation, final maturation of the spermatids (stages I‐VII), onset of meiosis (substage VIId), and completion of meiotic divisons (stage XIV) may be involved in this interaction.
Cytoskeletal organization and synthesis in substrate‐independent and ‐dependent myogenesis in chick embryos
Authors: Daniels Karla J. , Sandra Alexander
Published: February 2005

Chick embryo myoblasts were fused in suspension culture to form myoballs by modification of previous procedures that excluded the use of divalent ion chelators and antimitotic drugs and included the continuous presence of serum in order to analyze the organized appearance and synthesis of major cytoskeletal proteins during cell attachment and spreading. The organization of the major cytoskeletal proteins actin, tubulin, and vimentin was assessed by fluorescence microscopy under these conditions as well as under conditions in which the myoballs were allowed to attach and spread on a collagen‐coated substrate. Actin, detected by fluorescence microscopy, stained myoballs diffusely and was reorganized to form stress fibers in the attached and spreading myoball. Nuclei were segregated to a centrally located lattice of microtubules. The microtubule‐specific drugs nocodazole and taxol prevented myoball spreading and the establishment of myotube polarity, respectively. Vimentin appeared as wavy ribbons in a perinuclear position around attached and spreading myoballs. In parallel studies, the synthesis of these cytoskeletal proteins was analyzed by radioisotopic labeling and polyacrylamide gel electrophoresis. These studies showed that myoballs possess altered ratios of actin and tubulin isoforms and of phosphorylated and nonphosphorylated vimentin compared to myotubes. These ratios rapidly change to the myotube pattern when myoballs are allowed to attach to solid substrata. Thus, although both myoballs and myotubes undergo muscle‐specific differentiation, their cytoskeletal proteins are morphologically and biochemically distinct.
Morphological analysis of contracting and quiescent adult rabbit cardiac myocytes in long‐term culture
Authors: Decker Marlene L. , Simpson David G. , Behnke Monica , Cook Melissa G. , Decker Robert S.
Published: February 2005

Isolated rabbit ventricular cardiac myocytes adapt readily to primary culture. As the myocytes spread and flatten over the culture substratum, the myofibrillar apparatus retains a “rod‐like” orientation. Development of contractile activity is crucial in the maintenace of the integrity of the myofibrillar apparatus during prolonged culture. Myocytes that fail to beat display morphological indications of atrophy; conversely, myocytes that commence beating show no such morphological signs of myofibrillar disorganization. The subcellular organization of other elements of the contractile apparatus, including the transverse tubular system and the sarcoplasmic reticulum, retain their structural relationship with the myofibrils in beating myocytes but not in quiescent cells. Cultured adult myocytes represent an important model to investigate the influence of mechanical factors on the organization and maintenance of the adult cardiac phenotype.
Immunohistochemical localization of type X collagen in the proximal tibiotarsi of brolier chickens and turkeys
Authors: Haynes Joseph S.
Published: February 2005

Type X collagen is a prominent component of the extracellular matrix in cartilage destined to mineralize during endochondral ossification, yet its role is only now being determined. As a prelude to determining what, if any, alterations occur in the distribution of type X collagen in growth plates of poultry with rickets or tibial dyschondroplasia, our objective in the current study was to determine the distribution of type X collagen in the proximal tibiotarsi of broiler chickens and turkeys from 1 day of age through physeal closure. Proximal tibiotarsi from five male broiler chickens, five female broiler chickens and five male turkeys were collected at 1, 7, 14, 28, 56, and 98 days of age and processed for immunohistochemistry; a monoclonal antibody for type X collagen was used to demonstrate type X collagen distribution.

Our findings indicate that type X collagen is produced in the prehypertrophic and early hypertrophic zones of the avian growth plate and is incorporated into the extracellular matrix in these zones. Furthermore, intracellular type X collagen is markedly decreased in more mature areas of the growth plate, although type X collagen is markedly decreased in more mature areas of the growth plate, although type X collagen remains a prominent component of the extracellular matrix unitl the matrix is completely resorbed. In addition, the distribution of type X collagen is similar in the proximal tibiotarsi of broiler chickens and turkeys at comparable stages of endochondral ossification and distribution of type X collagen in the secondary center of ossification parallels that in the physis.
Induction of stein‐leventhal‐like polycystic ovaries (PCO) in the rat: A new model for cystic ovarian disease
Authors: McCarthy Gerald F. , Brawer James R.
Published: February 2005

An injection of estradiol valerate (EV) in the rat produces an anovulatory polycystic ovarian (PCO) condition. Chronic estrogen exposure, produced by subcutaneously implanted, estradiol (E2)‐containing chronic release capsules, results in acyclicity and in hypothalamic changes similar to those seen in the EV‐injected rat. We, therefore, examined the ovarian histology and plasma gonadotropin patterns in the E2‐implanted rat and found that this model exhibits a poiycystic ovarian condition and a plasma gonadotropin pattern very different from those in the EV‐treated model. The plasma patterns of LH and FSH are bimodal consisting of small frequent pulses as well as less frequent large episodes of long duration. The ovaries contain multiple small cysts, characterized by an extensively hypertrophied theca interna, and vast chords of hypertrophied secondary interstitial cells. In contrast, cystic follicles in EV‐treated rats are fewer in number, but much larger than those in the E2‐implanted animals. The cystic theca and the secondary interstitial cell clusters are also far less extensive in the EV‐induced poiycystic ovary. These and other differences between the two types of PCO indicate that they are produced by fundamentally different morphogenic mechanisms. The cystic ovary produced by the E2 implants is similar in appearance to that seen in the human Stein‐Leventhal condition, and thus provides a new model for the study of cystic ovarian disease.
An HRP study of location of the rabbit palatopharyngeal motoneurons and peripheral course of their axons
Authors: Kitamura Seiichiro , Ogata Kimio
Published: February 2005

The location of the rabbit palatopharyngeal motoneurons and the peripheral course of their axons were investigated with intramuscular injection of HRP either in the normal animal or in conjunction with intracranial severing of the vagal rootlets. Labeled palatopharyngeal motoneurons were ipsilaterally located within a subdivision of the nucleus ambiguus which is formed by a compact arrangement of the smallest neurons of the nucleus and situated in the rostral half of the nucleus. We named that subdivision the compact cell group (CoG). The labeled motoneurons occupied the caudal half of the CoG at a level from about 500 to 1,900 μm rostral to the obex. Labeling was completely abolished by severing the vagal rootlets, indicating that the axons of the palatopharyngeal motoneurons traversed the vagal rootlets.
Araldite F as injection material for quantitative morphology of cerebral vascularization
Authors: Van Der Zwan Albert , Hillen Berend
Published: February 2005

This study deals with the applicability of Araldite F as injection medium for quantitative morphology of the cerebral vascularization. The physical properties of the plastic that are essential for obtaining optimal results have been determined and tested by injection into the cerebral vessels of ten dog brains and five human brains. The dynamic viscosity (at 20°C) of the plastic is 1.5 times that of blood. The polymerization time (±45 min) is long enough to fill the whole vascular tree in a large organ such as the human brain. The plastic shows minimal volume shrinkage (3.90% ± 0.05%), and the final cast is suitable for scanning electron microscopy (SEM) investigation after corrosion and histological morpho‐metrical examination after embedding in 2‐hydroxyethyl‐methacrylate (GMA). Special attention has been paid to the conditions under which injection of Araldite F into the cerebral arteries must take place to obtain the most accurate quantitative data on cerebral vascularization and vascular area distribution. Simultaneous injection of the major cerebral arteries of fresh autopsy material, after having removed blood clots by perfusing Kabikinase, is recommended.
Adaptation of diaphyseal structure to aging and decreased mechanical loading in the adult rat: A densitometric and histomorphometric study
Authors: Li Xiao Jian , Jee Webster S. S.
Published: February 2005

Nine‐month‐old female rats were subjected to right hindlimb immobilization or served as controls for 0, 2, 10, 18, and 26 weeks. They were double‐labeled with bone markers prior to sacrifice. Experimental unloading was produced by immobilizing the right limb against the abdomen with an elastic bandage. Single‐photon absorptiometry was performed on the intact femurs; static and dynamic histomorphometry were performed on 20‐μm thick toluidine blue‐stained, undecalcified cross sections of the tibial shafts. Changes in the continuously immobilized tibiae were compared to those in both tibiae of age‐matched controls.

Unloading shut off nearly all periosteal bone formation and accelerates bone marrow expansion over that which occurs in age‐related controls. The effects of unloading appeared to be mediated by recruiting fewer osteoblasts which showed inhibited activity. Furthermore, unloading increased endocortical percentage eroded surface. These histological changes lowered cortical bone mass by inhibiting diaphyseal cross sectional expansion and enlarging the bone marrow cavity. The results support Frost's suggestion that decreased mechanical usage depresses bone modeling‐dependent bone gain by decreasing activation of modeling in the formation mode. It also stimulates bone remodeling‐dependent bone loss by increasing activation of remodeling in the resorption mode.
Expression of a fast myosin heavy chain mRNA in individual rabbit skeletal muscle fibers with intermediate oxidative capacity
Authors: Dix David J. , Eisenberg Brenda Russell
Published: February 2005

In situ hybridization (ISH) of myosin heavy chain (MHC) mRNA, immunofluorescent detection of MHC protein, and oxidative enzyme histochemistry were performed on the same fibers in serially sectioned rabbit skeletal muscle. By combining these three techniques quantitatively, on a fiber‐by‐fiber basis, fibers that expressed mRNA complementary to a fast MHC cDNA pMHC24–79 of unknown subtype (Maeda et al., 1987) were classified into fiber types with respect to slow myosin expression and oxidative capacity. As expected, slow fibers had low hybridization to pMHC24–79. Fast fibers were divided into three subtypes. mRNA from the low oxidative fibers (fast‐glycolytic, IIB) did not hybridize with pMHC24–79. Fast fibers whose mRNA hybridized best to pMHC24–79 were mainly in the intermediate range of oxidative capacity (probably IIX). The fast fibers with the highest oxidative capacity had low hybridization to this MHC mRNA (probably IIA). Thus, pMHC24–79 was identified as a clone of a fast isomyosin, tentatively designated as the fast IIX with intermediate oxidative capacity. The expression of more than a single species of fast and slow isomyosin mRNAs in classically defined fiber type was considered in interpreting these results.
Muscle spindle ultrastructure revealed by conventional and high‐resolution scanning electron microscopy
Authors: Patten Robert M. , Ovalle William K.
Published: February 2005

Muscle spindles in the tenuissimus muscle of mature golden Syrian hamsters were examined by conventional and high‐resolution scanning electron microscopy (HRSEM). For conventional SEM, entire muscles were first fixed in 2.5% buffered glutaraldehyde. Spindles were then isolated with a dissecting microscope under darkfield illumination and postfixed in 1.0% OsO4. Some spindles were treated with 8 N HCl at 60°C to clearly expose intrafusal fiber surfaces once the outer capsular sheath was mechanically disrupted. Preparation for HRSEM included aldehyde/osmium fixation and freeze‐cleavage in liquid N2. The cytosol and certain cellular elements were also selectively extracted by immersion in 0.1% OsO4 for varying time intervals. In these preparations, the capsular sleeve showed a multilayered pattern of vesicle‐laden cells with variant surface topography in different regions, including filopodia and small bristle‐like surface‐projections. An interlacing three‐dimensional network of collagen fibrils intervened between the capsular lamellae. Within the spindles, sensory and fusimotor nerve endings closely adhered to the outer surfaces of intrafusal fibers. Sensory nerve terminals were enveloped by a prominent external lamina, and those that were cleaved open contained a plethora of elongated mitochondria that ran parallel with the longitudinal axis, along with vesicles, axoplasmic filaments, and lysosomes. Multiple adhesion sites between the sensory nerve membrane and the underlying sarcolemma of the intrafusal fiber were also observed in select regions. Fusimotor nerve endings were covered externally by processes of Schwann cells and their axoplasm was filled with a multitude of cellular organelles and synaptic vesicles. Dilated cisternae of the sarcoplasmic reticulum and numerous mitochondria were, in addition, observed below the postjunctional sarcolemma at the neuromuscular interface. The methodology used in this study provides a novel view of the exquisite three‐dimensional architecture of this complex neuromuscular receptor.
Influence of age on nuclear bodies and nuclear volume in pituicytes of the rat neurohypophysis
Authors: Lafarga M. , Berciano M. T. , Pérez‐Fígares J. M. , Andrés M. A. , Maquiera E.
Published: February 2005

This study has analyzed age‐related changes in the nuclear organization of pituicytes of the rat. The cytological study of the cell nucleus and the quantitative analysis of nuclear bodies (NBs) were performed on ultrathin sections. Nuclear diameter, perimeter, and area were measured on semithin sections, and nuclear volume was estimated from these data. The nucleolus was mainly composed of a few large fibrillar centers with their associated dense fibrillar component, whereas the granular component tended to form large masses at the nucleolar periphery. The most frequent configuration of NBs was a globular inclusion composed of a fibrillar capsule with a core that contained a few electron‐dense granules. Intranuclear glycogen was detected on rare occasions and only in old rats. The proportion of nuclear sections containing NBs increased significantly from 1.5% in 3‐month‐old rats to 8.6% in 18‐month‐old rats. A significant increase in the nuclear volume was detected in older rats with respect to the younger ones (157±69 vs. 98±43 μm3, mean ±S.D.). Our results suggest an age‐related activation of nuclear metabolism in pituicytes resulting in a nuclear expansion and an increase in the frequency of appearance of NBs. This activation might be a reactive cellular event induced by the degenerative changes in neurosecretory nerve endings naturally occurring in older animals.
Adaptation of diaphyseal structure with aging and increased mechanical usage in the adult rat: A histomorphometrical and biomechanical study
Authors: Jee Webster S. S. , Li Xiao Jian , Schaffler Mitchell B.
Published: February 2005

The experimental increase in mechanical usage or overloading of the left hindlimb was produced by immobilization of the contralateral hindlimb. The right hindlimb was placed in a flexed position against the body and was immobilized using an elastic bandage. Some control animals were sacrificed initially at time zero and increased mechanical usage and age‐matched control animals were sacrificed after 2, 10, 18, and 26 weeks of treatment. All animals received double bone fluorochrome labeling prior to sacrifice. Cortical bone histomorphometry and cross‐sectional moments of inertia were determined. Marrow cavity enlargement and total cross‐sectional area expansion represented the age‐related cortical bone changes. Increased mechanical usage enhanced periosteal bone modeling in the formation mode and dampened endocortical bone remodeling and bone modeling in the resorption mode (resorption drift) to create a slight positive bone balance. These observations are in general agreement with Frost's postulate for mechanical effects on bone modeling and remodeling (Frost, H.M. 1987b. Bone “mass” and the “mechanostat.” A proposal. Anat. Rec. 219:1–9). The maximum moment of inertia did not change significantly in either control or overloaded tibial shafts. The minimum and polar moment of inertias in overloaded bones increases over those of controls at 18 and 26 weeks of the experiment.
The structural organization and adrenergic innervation of the carotid arterial system of the giraffe (Giraffa camelopardalis)
Authors: Kimani James Kirumbi , Opole Isaac O.
Published: February 2005

The sympathetic innervation of the giraffe (Giraffa camelopardalis) carotid arterial system is described in this study using the sucrose‐potassium phosphate‐glyoxylic acid (SPG) method. The brachiocephalic and bicarotid trunks showed a paucity of sympathetic innervation. Smooth muscle nests observed in the outer layers of the tunica media in these arteries revealed a rich network of sympathetic nerve fibres. The common carotid artery showed numerous sympathetic nerve fibres particularly in the outer muscular zone of the tunica media. The internal maxillary, ramus anastomoticus, and arteria anastomotica also revealed a rich sympathetic innervation and a deep penetration of the nerve fibres into the tunica media. It is suggested that the rich sympathetic innervation of the giraffe carotid arteries maintains a basal tonic state in the smooth muscle in the tunica media. This, in turn, may enable the animal to maintain a relatively high rate of blood flow in the carotid arteries in diastole despite the pressure run‐off. It is further suggested that the muscular structure and dense sympathetic innervation of the internal maxillary and its branches to the carotid rete mirabile provide the animal with an array of mechanisms to modulate its cranial circulation particularly when it bends its head to drink.
Ultrastructural study of the hyaline layer of the starfish embryo, Pisaster ochraceus
Authors: Campbell Stephen S. , Crawford Bruce J.
Published: February 2005

The hyaline layer (HL) is a multilayered extracellular matrix (ECM) that coats the external surfaces of sea urchin and starfish embryos. It is thought to protect and lubricate the embryo, stabilize the blastomeres during morphogenesis, and regulate nutrient intake. Ultrastructural studies of chemically fixed embryos have shown the HL to consist of two to four sublayers. However, since chemical fixatives may cause collapse and alter the positions and antigenicity of the extracellular components, fixation methods that exclude chemicals may reveal a picture of the HL closer to what is present in vivo. Freeze substitution, a fixation method whereby tissues are rapidly frozen and dehydrated at low temperatures, has proved useful for fixing material rich in ECM. In this study, embryos of the starfish Pisaster ochraceus were fixed for microscopy using freeze substitution and three chemical methods in order to determine, as accurately as possible, the structure of the HL. Embryos appear to be best preserved by freeze substitution and demonstrate a HL consisting of at least six distinct sublayers. Based on staining with anionic dyes, most sublayers appear to contain glycosaminoglycans. Freeze substituted embryos, which were also stained with monoclonal antibodies raised against their ECM, revealed that some molecules are common to all six sublayers, whereas other molecules may be restricted to specific sublayers. This suggests that each sublayer could have a different function. Additional evidence suggests that microvillus associated bodies, present in other marine invertebrate embryos, may anchor the asteroid HL to the cell surface microvilli.
Alteration of the mammotroph Golgi complex by the dopamine agonist 2 BR‐α‐ergocryptine (CB‐154) in ovariectomized estrogen primed rats
Authors: Poole Max C. , Easley Charles S. , Hodson Charles A.
Published: February 2005

The present study examined the acute effects of 2 Br‐α‐ergocryptine (CB‐154, a dopamine agonist) on mammotroph organelles during prolactin (PRL) suppression. Ovariectomized estrogen‐primed rats received a single injection (sc) of 0.5 mg CB‐154 and the animals were killed at intervals following injection. The anterior pituitary glands were fixed for electron microscopy and immunocytochemistry was used to confirm mammotroph identification. Serum PRL levels were determined by RIA. Following CB‐154 administration, serum PRL was significantly (P ≤ 0.05) reduced within 15 minutes and was suppressed (P ≤ 0.01) to ovariectomized levels at 2 and 6 hours. A stereological analysis of mammotrophs in the central regions of the anterior pituitary showed that the Golgi complex volume was significantly (P ≤ 0.05) reduced at 2 hours after CB‐154 treatment. However, the Golgi complex volume had recovered by 6 hours post CB‐154 injection. In addition, the volumes of the mammotroph cells, the mature secretory granules, and the secondary lysosomes had significantly increased by 6 hours. There were no significant changes in any of the organelles following CB‐154 in the mammotrophs from the peripheral regions of the gland. These studies show that the Golgi complex is especially susceptible to acute morphological changes induced by bromocryptine and that the mammotrophs in the central regions are more responsive to CB‐154 than those in the peripheral regions.
Simultaneous localization of histamine and factor VIII‐related antigen in the endothelium of the human umbilical vein
Authors: Ueda Hiroshi , Doi Yoshiaki , Sakamoto Yoshitaka , Hamasaki Kunshige , Fujimoto Sunao
Published: February 2005

Simultaneous immunoelectron microscopic localization of histamine and factor VII‐related antigen was examined on the same ultrathin section of the endothelium of the human umbilical vein from full‐term deliveries by means of the double‐immunolabeling technique.

Small gold particles demonstrating antibody reaction with histamine are preferentially located in the cytoplasmic matrix and organelles, especially in mitochondria and on the luminal membrane surface of the endothelial cells. The gold particles representing histamine immunoreactivity also located on some of Weibel Palade (WP) bodies. In contrast, large gold particles demonstrating factor VII‐related antigen are concentrated preferentially on most WP bodies. Single labeling of either histamine or factor VIII‐related antigen shows similar results to those of the double labeling.

The present study indicates that some WP bodies are involved in storage of both factor VIII‐related antigen and histamine, but others store factor VIII‐related antigen only. This difference in contents of WP bodies may be induced during the development and maturation process of this inclusion. At any rate, it is reasonable to consider that WP bodies have important roles in both vascular tonus and hemostasis during the vascular obliteration.
Tropic effects of otic epithelium on cochleo‐vestibular ganglion fiber growth in vitro
Authors: Hemond Sharon G. , Morest D. Kent
Published: February 2005

Sensory nerve fibers of the cochleo‐vestibular ganglion (CVG) innervate the otic epithelium in the early chick embryo by directed growth. To see if the target tissue could exert a tropic influence, we co‐cultured CVGs from chick embryos (Hamburger‐Hamilton stages 16–30) in a 3D collagen matrix with their normal target epithelium or with other epithelial tissues taken from the same or different stages of development. The pattern of neurite outgrowth and the viability of the CVG after five days in vitro were assessed histologically with a silver method. On the basis of the patterns of neurite outgrowth directed toward the epithelium the cultures were classified as having slightly, mostly, exclusively, or no directed outgrowth. Of 49 cultures containing otic epithelium, 33 had mostly or exclusively directed growth patterns. This effect did not depend on any particular stage difference between co‐cultures or on their viability in vitro. Cultures of non‐sensory otic epithelium (endolymphatic duct) also presented directed growth patterns. Co‐cultures with ectoderm from forelimb or visceral arch had little, if any, directed growth. The directed growth could not be explained simply as a result of guidance by non‐neuronal cells or of the viability of the explants. The results are consistent with the hypothesis that the otic epithelium provides a tropic factor that attracts growing CVG fibers.
Morphological and northern blot analysis of juxtaglomerular cells in experimental hydronephrotic mice
Authors: Kon Yasuhiro , Takahashi Shigeru , Fukamizu Akiyoshi , Murakami Kazuo , Hashimoto Yoshiharu , Sugimura Makoto
Published: February 2005

The purpose of this study is to demonstrate the developmental changes of the experimental hydronephrotic kidney using immunohistochemical, histoplanimetrical, and Northern blot techniques. At 1 month after ligation of the ureter, a large number of renin‐positive cells were detected immunohistochemically even at a dilution of 1:10,000 in this hydronephrotic kidney; however, there were few renin‐positive cells in the non‐ligated side. At 6 months after ligation, no difference in reactivity for renin between ligated and non‐ligated kidneys was demonstrated. In the morphometrical analysis of the renin‐positive region, the numerical value of the ligated side was already increased at 2 weeks, reached the highest value at 1 month, and then decreased gradually to almost the same value as the control kidney by the end of the experiment. On the other hand, the value of the non‐ligated side decreased immediately after the unilateral ligation, increased later, and finally reached almost the same value as the control kidney. In the Northern blot analysis, the activity of renin mRNA in the ligated side at 1 month after ligation was markedly higher than that in the non‐ligated side. However, the difference between the ligated and the non‐ligated sides was not demonstrated at 6 months and the value came to be almost the same as in the nonoperated kidney.
Morphologic and functional characteristics of subpopulations of murine lung fibroblasts grown in vitro
Authors: Penney D. P. , Keng P. C. , Derdak S. , Phipps R. P.
Published: February 2005

Fibrotic development is a common response of the lung to toxic or deleterious insult. For example, the lung is the dose‐limiting organ for irradiation of the thorax for primary or metastatic lesions, due in large part to latent fibrosis. The development of the fibrotic response reflects a cascade of cell‐cell and cellextracellular matrix interactions, the ultimate target of which is the fibroblast. There is increasing evidence of subpopulations of pulmonary fibroblasts, which may have differing roles in either the initiation or progression of fibrosis. Recently we described two fibroblast subpopulations from the murine lung, which differ in the presence or absence of the membrane antigen Thy‐1 (Phipps et al., 1989). These Thy‐1+ and Thy‐1− subpopulations are stable and differ in certain functions, such as the production of cytokines and the display of Class II MHC antigens. To determine the morphologic development of the two subpopulations and their growth characteristics in vitro, cultures of the two cell subtypes were prepared for transmission and scanning electron microscopy at varying stages of growth. Thy‐1+ fibroblasts are more spindle‐shaped, contain intracellular lipid, exhibit abundant cell‐cell contacts, and are capable of secreting large amounts of collagen and modest amounts of fibronectin. Thy‐1− fibroblasts are more rounded and spread, contain no intracellular lipid droplets, possess more intracellular microfilaments and microtubules, and synthesize less collagen and more fibronectin than do Thy‐1+ cells. There are no significant differences between the two subpopulations insofar as growth rates are concerned, but Thy‐1+ fibroblasts possess an additional DNA peak during periods of early growth.
Supra‐neuroectodermal cells and fibers on the primary nasal cavity and in the fourth ventricle of mouse and human embryos: Scanning and transmission electron microscopic studies
Authors: Otani Hiroki , Tanaka Osamu , Yoshioka Takafumi
Published: February 2005

Neuroectoderm‐derived epithelia of the primary nasal cavity and the fourth ventricular floor and roof were observed by scanning (SEM) and transmission electron microscopy (TEM) and SEM‐TEM correlative views in mouse embryos of 9th to 13th days of gestation, and in 38 externally normal human embryos ranging at Carnegie stages from 13 to 18 (about 5 to 7 weeks of gestation). Smooth‐surfaced spindle‐shaped cells with one or more cytoplasmic processes and cord‐like cytoplasmic structures were observed by SEM on the wall of the primary nasal cavity of both species. They had morphological features similar to those of neuronal type 1 supraependymal (SE) cells and SE fibers on the floor and roof of the fourth ventricle in both species. Type 1 SE cells, SE fibers, and corresponding structures in the primary nasal cavity were localized in relation to the underlying developing nerve and vascular systems. Furthermore, their processes and fibers ran roughly parallel to these underlying structures and they penetrated the epithelial layer at the ends, suggesting a connection with underlying structures. From TEM and SEM‐TEM correlative observations, SE fibers in the fourth ventricle and cord‐like structures in the primary nasal cavity, both with a larger diameter, were deduced as single axon‐like processes or bundles of processes. Those fibers and cord‐like structures of smaller diameters were interpreted as elongated telophase bridges; both contained parallel packed microtubules and connected distant cells. Since these processes and fibers were generally longer and became fewer at later developmental stages, they appeared to be transient neuronal structures. They may play a development‐related role in such morphogenetic cell movements as in the developing nerve and vascular systems in the epithelial and/or subepithelial layers, but not as direct rudiments of adult nerve tissues. © 1992 Wiley‐Liss, Inc.
Nerve growth factor receptor (NGFR)‐like immunoreactivity in the perineurial cell in normal and sectioned peripheral nerves of rats
Authors: Yamamoto Miyuki , Kondo Hisatake , Iseki Shoichi
Published: February 2005

The occurrence of nerve growth factor receptor (NGFR)‐like immunoreactivity in the perineurial cells of sympathetic and sensory nerves was analyzed in normal controls and after surgical severance. In the normal nerve trunk, no cellular elements exhibited NGFR‐like immunoreactivity. Immunoreactivity was induced in the innermost perineurial cells and in all Schwann cells distal to a severed nerve. The acquisition of immunoreactivity in perineurial cells was also seen in deafferented sympathetic ganglia. On the other hand, the perineurial cells as well as axonal endings showed NGFR‐like immunoreactivity consistently in the terminal region of normal nerves, and this immunoreactivity was enhanced by nerve section. The present study clearly showed that different types of nerve terminals are ensheathed to different extents by perineurial cells which were first clearly identified by their NGFR‐like immunoreactivity: (1) nerve terminals were free of the perineurium far away from targets in the iris, (2) they were free of the perineurium at sites close to targets in the lingual epithelium, and (3) the perineurium ensheathed nerve terminals together with targets in Meissner's sensory corpuscle. The functional significance of the three different patterns of perineurial enclosure requires further examination. © 1992 Wiley‐Liss, Inc.
Detailed anatomy of the antebrachiocarpal joint in dogs
Authors: Mikić Ẑ. Dj. , Ercegan G. , Somer T.
Published: February 2005

A comparative study of the anatomy of the antebrachiocarpal (AC) articulation was carried out in 30 adult dogs with 60 joints. Although a considerable degree of similarity was found between the AC joint in dogs and the corresponding wrist joint in humans, a number of differences between these two homologous joints were also noted. The distal end of the ulna in dogs directly articulates with the ulnar carpal and accessory carpal bones forming a specialized antebrachiocarpal arrangement more adapted to running. The accessory carpal bone in dogs is a massive, long bone and is strikingly different from its homologue in humans, the pisiform bone. The joint between the accessory and ulnar carpal bones, which corresponds to the piso‐triquetral joint in humans, is always connected with the AC joint, whereas in humans this communication could be found occasionally. The large radial carpal bone in dogs, characteristic for carnivores, corresponds to the fused scaphoid and lunate bones in humans, in whom this type of fusion is very rarely found. The palmar ulnocarpal and radiocarpal ligaments in dogs are distinctly intra‐articular, whereas in humans these ligaments are intracapsular. One of the controversies of the AC joint in dogs is a structure located between the distalmost parts of the radius and ulna forming a strong bond between these two bones and a part of the antebrachial articular surface. It is cartilage‐like and is composed of typical fibrocartilagineous tissue. Considering its location, form, and function, this structure in dogs should be regarded as the articular disc and so‐named; it is also concluded that it is a homologue to the articular disc of the distal radioulnar joint in humans. © 1992 Wiley‐Liss, Inc.