bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pituitary tumorigenesis in aging female C57BL/6J mice: A light and electron microscopic study
Authors: Schechter Joel E. , Felicio Leda S. , Nelson James F. , Finch Caleb E. 
Published: February 2005

AbstractSpontaneous pituitary tumors have been studied by light and electron microscopy in female C57BL/6J mice at 2½, 11, 15, 22, 23, 24 and 30 months. Tumors were evident macroscopically in greater than 50% of mice 22 months or older, and greater than 80% on microscopic evaluation. Active and hypertrophied mammotrophs were the predominant cell type within the tumors at 22‐‐30 months, often totally filling large portions of the tumor mass. Exocytosis of secretory granules was extensive from the mammotrophs, but much less abundant from other parenchymal cells. Somatotrophs and gonadotrophs were also present, and appeared active and often strikingly hypertrophied. The tumors were characterized by disruptions of parenchymal and capillary integrity which resulted in the formation of large vascular lakes lined solely by tumor cells, generally mammotrophs. Apparent metastasis of tumor cells into the vascular lakes was also observed. In 11‐ and 15‐month mice small tumors or pretumor foci were evident in some mice on microscopic evaluation, although they were not visible macroscopically. Their degree of development was somewhat variable, but they had essentially the same features as more advanced tumors in older mice. Pretumor foci were characterized by more moderate disruptions of parenchymal cell and capillary integrity; cellular hypertrophy, particularly of somatotrophs and gonadotrophs; and the presence of small vascular lakes. In 2½‐month mice tumors could not be localized macroscopically or microscopically, and the pituitary was composed of well‐defined cell cords and an intact capillary bed. However, small focal zones of capillary and tissue disruption were apparent occasionally in 2½‐month mice. These findings indicate that the process of pituitary tumorigenesis in female C57BL/6J mice is initiated by midlife, with subsequent progressive development into large, mammotroph‐dominated tumors.
Growth of the turtle Chrysemys scripta under constant controlled laboratory conditions
Authors: Sarnat Bernard G. , McNabb Elizabeth , Glass Michael 
Published: February 2005

AbstractThe purpose of this study was to determine (1) growth of the turtle shell and change in weight under constant controlled laboratory conditions and (2) whether under these constant conditions there were seasonal changes. Fifty unfed refrigerated eight‐week‐old hatchling turtles Chrysemys scripta were received in October and maintained in aquaria with 16 hours of artificial light and eight hours of darkness, at 24–27°C and a humidity of 30% and fed twice weekly. Gross linear measurements of the width and length of the plastron and carapace, and total body weights, were taken at eight weeks and thereafter at about six‐week intervals. During the two‐year period the mean increase of the plastron length was from 30.79 ± 0.19 mm to 68.32 ± 1.58 mm, plastron width from 24.23 ± 0.20 mm to 50.43 ± 1.03 mm; carapace length from 32.47 ± 0.24 mm to 75.21 ± 1.82 mm, carapace width from 31.81 ± 0.28 mm to 67.12 ± 1.29 mm, and body weight from 6.94 ± 0.15 gm to 80.63 ± 5.02 gm. Calculated daily percent changes revealed that as the turtles aged, the rates decreased. At 56 days of age, weight was the most strongly correlated with its value at 786 days of age. No seasonal differences in growth were noted between the summer and winter periods when turtles would enter winter dormancy in certain natural environments. Environmental factors are reflected in the growth of the turtle.
Morphology of a two‐headed piglet
Authors: Partlow Gary D. , Barrales Dorothy E. , Fisher Kenneth R. S. 
Published: February 2005

AbstractA live‐born, one‐day‐old diprosopic piglet was presented to the Ontario Veterinary College. The piglet had a normal body with two heads, joined in the occipital region. There were two complete snouts, four eyes and three ears. The lower jaws were immobile because of overlapping mandibular rami. Although there was only one vertebral column, the bodies of the vertebrae, but not the neural arches, were doubled from the axis to T8. There was one thyroid gland and one larynx and hyoid apparatus. The two tongues were joined at their base just rostral to the single epiglottis. The palate was completely split in the right head but only partially split in the left. The cranial nerves were normal and doubled except for IX, X and XI. The brains were fused at the pons‐medulla junction. An anomalous midline tag of neural tissue resembling remnants of the medial halves of two nervous systems extended from this point to the level of T8. Possible developmental mechanisms and rates of incidence are discussed.
A freeze‐fracture study of avian epiphyseal cartilage differentiation
Authors: Borg Thomas K. , Runyan Raymond , Wuthier Roy E. 
Published: February 2005

AbstractThe morphological features of avian epiphyseal cartilage have been investigated by freeze‐fracture techniques. Progressive changes occurred in both the cells and the matrix during differentiation. Chondrocytes changed in shape from small flattened cells with few, short cellular processes, to enlarged ovoid cells with numerous long processes often associated with extracellular vesicles. In the matrix these vesicles appeared first in the cellular lacunae, then in the extralacunar matrix, becoming larger and more numerous. Large membrane‐associated particles (MAPS) were seen on the p faces of the plasmalemma. These became progressively concentrated on and around the cellular processes, with few large MAPS being seen on the e face. Similar distribution of MAPS was seen in the matrix vesicles. Domains of hydrated proteoglycan aggregates were manifest as regular fracture patterns in the extralacunar matrix of the upper regions of the plate. Collagen fibrils progressively increased in size and state of aggregation, often being associated with matrix vesicles and in the end, with long plate‐like mineral crystals. These findings, while in basic agreement with patterns observed with TEM, reveal important new features concerning cellular and matrix structure during cartilage differentiation.
Role of microtubules in the organization of the Golgi complex and the secretion of collagen secretory granules by periodontal ligament fibroblasts
Authors: Cho Moon‐Il , Garant Philias R. 
Published: February 2005

AbstractFibroblasts of the periodontal ligament (PDL) of the mouse exhibit a high degree of cytoplasmic and functional polarity. This polarity is dependent upon an elaborate system of microtubules. The location of the microtubular arrays and the observed effects of colchicine administration suggest that microtubules play an important role in maintaining the organization of the Golgi complex and its functional relationship to the rough endoplasmic reticulum. Smooth‐walled intermediate vesicles, apparently derived from the rough endoplasmic reticulum, are aligned along microtubules at the immature face of the Golgi apparatus, and mature secretory granules are closely related to microtubules at the mature face of the Golgi apparatus. In distal cell processes the granules are closely parallel to microtubules and on occasion bridge‐like attachments from granules to microtubules were noted. This relationship of secretory granules to microtubules, the lack of granule storage, and the effects of colchicine on granule secretion suggests that microtubules are part of a mechanism for collagen granule translocation from the Golgi complex to the cell periphery.
A stereologic analysis of collagen phagocytosis by fibroblasts in three soft connective tissues with differing rates of collagen turnover
Authors: Svoboda E. L. A. , Shiga A. , Deporter D. A. 
Published: February 2005

AbstractThe purpose of this study was to assess the importance of the phagocytic mechanism of collagen resorption in the normal turnover and remodelling of soft connective tissues. Collagen phagocytosis by fibroblasts in rat skin, attached gingiva, and periodontal ligament was quantitated using the methodology of electron microscopic stereology. Periodontal ligament contained five and 15 times as much phagocytosed collagen as attached gingiva and skin respectively. Also, for each tissue examined, a positive correlation was observed between the amount of collagen phagocytosed and the known rate of mature collagen turnover.
Circadian rhythm in mitotic index of corneal epithelium: Presence of ehrlich ascites carcinoma and treatment with saline or hydroxyurea
Authors: Burns E. Robert 
Published: February 2005

AbstractA study of the circadian rhythm in the mitotic index (MI) of the corneal epithelium was completed in non‐tumor‐bearing mice and in mice bearing the Ehrlich ascites carcinoma (EAC). All mice were standardized to a light‐dark cycle with 12 hours of light from 0600 to 1800 CST alternating with 12 hours of darkness from 1800 to 0600 CST. Treatments included injection with saline (SAL) or hydroxyurea (HU) at different circadian times. This investigation demonstrated that: (1) Data from untouched animals cannot serve as proper controls because treatment with SAL altered the level of the MI, but only during the diurnal, not the nocturnal, phase of the circadian cycle; (2) the presence of the EAC depressed the level of the MI, but this inhibition was only detected during the diurnal period; (3) treatment with 500 mg/kg HU injected at 0500 caused more perturbation in this rhythm than did treatment with 500 mg/kg HU at 1700; (4) when 500 mg/kg HU was given at 2000 and 0100 and 0500, the perturbation of the rhythm was greater than when 500 mg/kg HU was given at 0900 and 1400 and 1700; (5) when 3000 mg/kg HU was given at 1700 and compared to 500 mg/kg HU at 1700, little difference in the overall circadian profiles of these rhythms was observed, indicating that the circadian control mechanisms operating on the MI exerted a greater influence than did a dosage change from 500 to 3000 mg/kg HU; and (6) a comparison of the practice of plotting experimental and control data as “hours after treatment” versus using a “time of day” plot for the same data demonstrated that the “hours after treatment” plot is very misleading because it fails to account for the significant circadian oscillation in this in vivo system.
Morphological profiles of cryptorchid XXY mouse testes
Authors: Huckins C. , Bullock L. P. , Long J. L. 
Published: February 2005

AbstractTwo mice with an XXY karyotype and cryptorchid testes appeared spontaneously in a colony. The animals were H‐Y antigen‐positive, and had elevated serum levels of follicle‐stimulating (FSH) and luteinizing (LH) hormones. Testes of the affected mice were atrophic, containing a few solid seminiferous cords surrounded by vast amounts of compact interstitial material. The cords were delimited by a broad tunica propria in which the basal lamina was irregularly thickened and stratified into a number of alternating dense and less dense layers. Most sex cords were populated by mature Sertoli cells and small pleomorphic elements resembling monocytic‐derived macrophages. Within some cords, the macrophages aggregated into a central mass with which identifiable Sertoli cells and (PAS) periodic acid Schiff‐positive fragments of basal lamina were associated. In more severely damaged cords, the basal lamina and peripheral carpet of Sertoli cells were totally missing. Such cords were populated only by the central macrophages with fragments of basal lamina and degenerating Sertoli cells. Finally, a few collapsed remnants of cords contained compact nodules of macrophages surrounded by what appeared to be the outer part of the tunica propria. The interstitial area, as well as the outer walls of the seminiferous cords were also heavily infiltrated by macrophages. Overall, the morphological picture was one of severe immunological injury. We do not know what role, if any, the genetic constitution and/or intra‐abdominal environment may play in the expression of these bizarre pathologies. However, such severe changes have not been reported in either Klinefelter's syndrome or the undescended testes of any human or subprimate species.
The mammary gland of the weddell seal, Leptonychotes weddelli (Pinnipedia). I. Gross and microscopic anatomy
Authors: Tedman R. A. , Bryden M. M. 
Published: February 2005

AbstractThe Weddell seal cow possesses two subcutaneous, ellipsoidal, abdominal mammary glands with a volume of two to three liters when lactating. Corrosion casts reveal that approximately ten large ducts radiate from a gland cistern at the base of the nipple, and end in a complex system of terminal branches. Each gland has a separate arterial supply, mostly from the caudal deep epigastric with a minor contribution from the deep circumflex iliac. Histologically, lactating, nonlactating (resting), and immature glands resemble those of other eutherians. Sinusoidal blood vessels, not observed in the mammary glands of other mammals, are present within lactating but not in resting lobules in the seal. The terminal pouch and lactiferous sinuses possess circular smooth muscle and elastic fibers in the walls, and accumulations of lymphocytes immediately beneath the epithelium. Sebaceous and sweat glands open into the walls of the nipple and the apex of the terminal pouch. There are extensive networks of blood vessels and longitudinal smooth muscle and elastic fibers in the walls and base of the nipple. The possible functions of these morphological observations are discussed.
Sympathetic innervation of murine thymus and spleen: A comparative histofluorescence study
Authors: Williams John M. , Felten David L. 
Published: February 2005

AbstractFluorescence microscopy of thymus and spleen from four strains of mice (C3H and ICR controls, AKR spontaneously leukemic and NZB autoimmune) revealed varicose noradrenergic (NE) fibers in perivascular and parenchymal regions of both organs. Thymic innervation was largely perivascular, but isolated islands and strings of free NE fibers were noted among thymic parenchymal cells. A morphological proximity between NE fibers in the thymus and mast cells was noted in all strains studied, but was exceptionally prominent in the NZB thymus. Perivascular plexuses within the splenic white pulp sent single NE fibers between the surrounding lymphocytes. Catecholamines and histamine have been shown to modulate lymphocyte development and activity in vitro. The present study provides morphological evidence that both NE and histamine are available to lymphocytes in thymus and spleen, and thus provides morphological evidence for neurla modulation of immune activity in vivo.
Ultrastructural study of the embryonic development in the rat pineal gland
Authors: Calvo J. , Boya J. 
Published: February 2005

AbstractThe ultrastructure of the albino rat embryo pineal gland was studied from day 13 of development through birth. In the first stages (13–16.5 days of development) the pineal evagination presents a barely differentiated epithelium. From 17 days onward the transformation of the pineal gland from a tubular evagination into a compact organ occurs. The obliteration of the recess takes place by means of two mechanisms: (a) multiple foldings of the epithelium which determine an approximation and fusion of the walls of the recess, and (b) occupation of the lumen by cells extruded from the pineal epithelium. Embryos of 18–21 days of gestation still show remains of the pineal recess.Frm day 16.5 onward elements of the pineal parenchyma have been found outside the pineal epithelium contour. They contact with the mesenchymal cells without a basal lamina separating both elements.Day 20 marks the beginning of recognizable differentiation of pineal cellular types. However, in the newborn rat these types are not yet clearly established.
The three‐dimensional cytoarchitecture and pattern of motor innervation of branched striated myotubes
Authors: Ontell Marcia , Feng K. C. 
Published: February 2005

AbstractThree‐dimensional reconstructions of “regenerating” myotubes in the “degeneration‐regeneration” regions and in the “regenerative” foci of the extensor digitorum longus muscle of the C57BL6J/dy2J myopathic mutant mouse were made from spaced serial ultrathin section. Complex branching and recombination occurred, involving myotubes which for extensive regions along their length appeared to be independent. No accumulation of specialized organelles occurred at the branching site. Continuous branches displayed multiple discrete motor endplates.
The presence of proximal tubulelike cells in the kidney parietal epithelium in response to unilateral nephrectomy
Authors: Andrews Peter M. 
Published: February 2005

AbstractFive months following unilateral nephrectomy, the parietal epithelia in the remaining kidneys of Sprague‐Dawley rats were examined by light and electron microscopy. Compared with controls, the kidneys from uninephrectomized rats exhibited a dramatic increase in mass characteristic of compensatory hypertrophy. Approximately 20% of the renal corpuscles in the hypertrophied kidneys had parietal epithelia lined by tall cells which possessed a brush border and other morphological characteristics of proximal tubule cells. In some instances proximal tubulelike cells made up over half of the cells lining the parietal epithelium. The possible significance of this finding is discussed.
Morphology of the buccopharyngeal portion of the gill in the fathead minnow Pimephales promelas (Rafinesque)
Authors: Walker Elizabeth R. , Fidler Stephen F. , Hinton David E. 
Published: February 2005

AbstractBuccopharyngeal epithelium covering gill arches and gill rakers of the fathead minnow was studied by light microscopic, scanning, and transmission electron microscopic techniques. Mature mucous cells in goblet pattern and nonmucus containing cells were in the apical one‐third of the tissue. The latter cells contributed to a surface microridge system which overlapped apices of goblet cells. The bottom of the epithelium was comprised of a continuous row of darkly stained basal epithelial cells. In this region, two to three epithelial cells of similar staining characteristics were piled up forming apical columns which partially encircled nests of lightly stained cells. A basal lamina and thick basement lamella of about 20 plies of orthogonally arranged collagen supported the epithelium. Numerous taste buds were seen in gill arches and rakers. Taste bud cellular components included marginal cells, light receptor cells, dark receptor cells, and basal cells. These were identical in all taste buds. Taste bud surface morphology differed between gill arch and raker. Pores of the former were depressed, while those of the latter were raised. Thick microvilli of taste pores were apical extensions of light cells, while smaller, more numerous microvilli were projections from dark cells.
The origins of the afferent fibers to the lingual muscles of the dog, a retrograde labeling study with horseradish peroxidase
Authors: Chibuzo Gregory A. , Cummings John F. 
Published: February 2005

AbstractThe origin of the afferent fibers to the lingual muscles of the dog was investigated by means of retrograde transport of horseradish peroxidase (HRP) from injection sites in the tongue and the extrinsic lingual muscles. Intralingual injections were not satisfactory because the enzyme diffused beyond the intrinsic lingual muscles to include virtually all tissues within the tongue. Thus, the resultant retrograde labeling of cell bodies of the trigeminal, geniculate, glossopharyngeal, vagal, and first cervical (C1) spinal ganglia represented a composite of lingual sensory innervation.In order to confine HRP uptake to intramuscular nerve endings, injections were limited to surgically isolated extrinsic lingual muscles, i.e., the genioglossus, hyoglossus, and styloglossus. After these intramuscular injections, labeled neurons appeared ipsilaterally in the C1 spinal ganglion, the proximal vagal (jugular) ganglion, and trigeminal ganglion. Earlier suggestions that the lingual proprioceptive neurons of the dog reside in the distal vagal (nodose) ganglion and hypoglossal ganglia were not confirmed. The mesencephalic nucleus of the trigeminal nerve failed to label after enzyme injections into the tongue or the extrinsic lingual muscles.The retrograde labeling of cell bodies in the C1 spinal ganglion was abolished when HRP injections into the extrinsic lingual muscles were preceded by surgical interruption of the ansa cervicalis or distal section of the hypoglossal nerve. Retrograde labeling of neurons in the proximal vagal ganglion persisted after hypoglossal nerve transections.
Quantification of microvasculature in the canine spinal cord
Authors: Ireland William P. , Fletcher Thomas F. , Bingham Christopher 
Published: February 2005

AbstractCapillary density and capillary orientation in canine spinal cords were estimated by calculating actual lengths, surfaces, and volumes of capillary segments in tissue sections. Transverse, sagittal, and frontal section planes were sampled from dorsal, ventral, and lateral funiculi and from dorsal and ventral gray horns of spinal segments C3, T6, and L3 from three dogs. Capillaries were defined as vessels less than 10 μm in diameter. Electron microscopy of 104 such vessels revealed no muscle coat but collagen fibrils between endothelium and astrocyte process in 68% of the white matter capillaries and 16% of those in gray matter. Capillary diameter was significantly different among regions in some cases, but consistent patterns of variation were not found. Capillary density was four to five times greater in gray matter than in white matter. Capillary density differed significantly among the same‐size dogs, but within dogs, density was similar among segments and within gray matter and white matter regions. In 62% of the transverse sections, capillary orientation was significant but mean direction was variable. Significant capillary orientation was found in 89% of the sagittal and frontal sections, and the mean direction was always along the craniocaudal axis of the spinal cord. The craniocaudal orientation was significant in 96% of the white matter sections and 78% of the gray sections, and in 97% of the cervical and thoracic sections but only 73% of the lumbar sagittal and frontal sections.Because capillary orientation is neither isotropic nor regular, unbiased, lowvariance estimates of capillary density cannot be expected without resorting to excessive sampling. An efficient method of quantifying spinal capillaries for comparative purposes by counting number of profiles per unit area is recommended.
Effects of cold and melatonin on the microtubules of the toad sciatic nerve
Authors: Piezzi Ramón S. , Cavicchia Juan C. 
Published: February 2005

AbstractThe effects of melatonin and cooling on the disintegration and reassembly of microtubules were studied in the sciatic nerve of the toad. Control and melatonin‐treated nerves showed disintegration of the majority of microtubules after 2 hours of cooling. When room temperature was restored, microtubules were reformed in the controls, but not in the nerves treated by melatonin where the disorganization persisted. These results demonstrate that melatonin interferes with the microtubular reassembly after cooling of the axons of the sciatic nerve.