bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioautography of rat incisor dentin as a continuous record of the incorporation of a single dose of 3H‐labeled proline and tyrosine
Authors: Josephsen K. , Warshawsky H. 
Published: February 2005

AbstractAfter injection of labeled precursors such as 3H‐proline or 3H‐tyrosine into rats, the incisor dentin contains a continuous and stable record of precursor incorporation into labeled proteins. This record was visualized and quantitated with radioautography in order to evaluate the quantitative changes in enamel where newly secreted proteins randomize with older proteins and both are eventually lost. Up to 4 hours after injection, the pulse‐dose was incorporated as a highly labeled band of predentin. The band was entirely within calcified dentin at 2 days and was further removed from new predentin by 4 and 8 days. Dentin which formed proximal to the heavily labeled band contained an amount of radioactivity reflecting the level of labeled precursor available at that time. A standardizing factor for experimental error was obtained by quantitating the reaction in the heavily labeled band, and a post‐pulse incorporation factor was determined from the amount of radioactivity added per day as weakly labeled dentin. The variation within the heavily labeled band was assumed to reflect experimental error. The number of grains in the bands were averaged from 4 hours to 8 days to give the standardizing factor. This was multiplied by the ratio of enamel to dentin counts in the same section to obtain a corrected enamel count. In this way the coefficient of variation was improved from a high of 17.2% in uncorrected enamel counts to 2.4% in corrected counts. The post‐pulse incorporation factor was higher with tyrosine than with proline. With proline it amounted to 5% increase per day from 1 to 4 days and 2.5% per day from 4 to 8 days after injection. In addition, with 3H‐proline the incorporation into predentin increased from 30 minutes to 4 hours. With tyrosine, the counts increased from 30 minutes to 1 hour, but decreased by nearly one third from 1 to 4 hours. This was interpreted as a loss of short‐lived matrix proteins including procollagen peptides produced during conversion from procollagen to tropocollagen in the predentin.
Intercellular junctions in the hematopoietic compartments of embryonic chick bone marrow
Authors: Sorrell J. Michael , Weiss Leon 
Published: February 2005

AbstractAvian embryonic marrow is segregated into distinct erythropoietic and granulopoietic compartments. Within each compartment presumptive stem cells and immature blood cells establish intimate contact with their respective stromal cell. In this study we have examined one aspect of potential hematopoietic cell‐stromal cell interaction by looking for the presence of inter‐cellular junctions between these two elements. In previous studies, after aldehyde fixation, junctions were not observed, but after perfusion fixation with tannic acid‐glutaraldehyde, pentilaminar junctions became evident. These junctions were most characteristically located in the intravascular erythropoietic compartment, but were also found in the extravascular granulopoietic compartment. Junctions frequently joined presumptive stem cells with sinusoidal endothelial cells as well as joining immature erythroblasts with sinusoidal endothelial cells; and less frequently, junctions connected adjacent erythroid cells. However, reticulocytes and erythrocytes were never seen to have formed junctions with any other type of cell. Similar junctions within the extravascular compartment connected contiguous reticular cells and also, on occasion, reticular cells with sinusoidal endothelial cells. Hematopoietic cell‐reticular cell junctions were restricted to two classes of blood cells—extravascular presumptive stem cells and mast cells. There was no evidence of junctions connecting mature or maturing granuloid cells and any other cell type. The presence of intercellular junctions between immature blood cells and their respective stromal cells suggests that such interactions might play an important role in avian hematopoiesis. However, further work will be needed to determine if these junctions are merely adherence sites or whether they represent sites of intercellular communication. In either event, these junctions appear to reflect a mechanism whereby the marrow stroma could regulate erythroid maturation.
Ultrastructure of terminally differentiated adult rat cardiac muscle cells in culture
Authors: Moses R. L. , Claycomb William C. 
Published: February 2005

AbstractVentricular cardiac muscle cells isolated from adult rats were maintained in culture for 28 to 60 days and examined by transmission electron microscopy. In order to elucidate the detailed ultrastructure of the cultured myocytes, several different electron‐dense stains were used. These included tannic acid, osmium ferrocyanide, osmium tetroxide (applied as a primary fixative), and lanthanum chloride, as well as more widely used stains such as osmium tetroxide, uranyl acetate, and lead citrate. Our results show that, compared to cultured neonatal rat myocytes, cultured myocytes derived from adult rats more closely resemble in vivo adult ventricular cells. The cultured adult myocytes contained typically distributed organelles such as nuclei, mitochondria, and elements of the sarcoplasmic reticulum. Myofilaments were well organized, and typical intercalated disks were observed between adjacent cells. Unlike cultured neonatal myocytes, the adult cells contained numerous residual bodies and a relatively well developed transverse tubular system. The transverse tubular system was identified by its continuity with the extracellular space (as indicated by the penetration of electron‐dense extracellular tracers), location at or near the Z line, large lumenal diameter, and frequent participation in couplings with elements of the sarcoplasmic reticulum.
Atrophy of the zona fasciculata in the adrenal cortex of thyroparathyroidectomized rats: A quantitative study
Authors: Conran Richard M. , Nickerson Peter A. 
Published: February 2005

AbstractAtrophy of the adrenal gland induced by thyroparathyroidectomy (TPX) is attributable primarily to narrowing of the zona fasciculata. But absolute volumes of the adrenal gland and zona fasciculata, not the zona glomerulosa and zona reticularis, were decreased significantly 7 weeks after TPX. Changes consistent with atrophy were also seen in the zona fasciculata by electron miscroscopy. A slight decrease in volume of cytoplasm in cells of the zona fasciculata was evident 2 weeks after TPX as shown by quantitative stereological techniques. Seven weeks after TPX, there was a significant decrease in average cytoplasmic volume as well as mitochondrial volume and surface density of mitochondrial membranes. A decrease in total volume of the zona fasciculata, as well as volume per cell of mitochondria, correlates directly with decreased production of corticosterone in response to stress in TPX rats. Parathyroidectomy (PX) had no effect on the volume of the adrenal gland, on the volume of the individual cortical zones, or on the volume per cell of cytoplasm or mitochondria; these observations indicate that changes in TPX rats are due primarily to ablation of the thyroid gland.
Quantitative morphological analysis of proliferating and nonproliferating subpopulations of IMR‐90 fibroblasts during aging in vitro
Authors: Pool Thomas B. , Heitman Teri O. , Buck Marilyn A. 
Published: February 2005

AbstractEarly‐, mid‐ and late‐passage cultures (population doubling levels 12, 35, and 51, respectively) of IMR‐90 fibroblasts were exposed to 3H‐thy‐midine for 48 h prior to fixation in situ for morphometric analysis in order to determine quantitatively what ultrastructural changes accompany the loss of proliferative capacity during aging in vitro. Analysis of autoradiographs, both at the light and electron microscopic levels, with an image analyzer followed by ANOVA statistical scrutiny demonstrated that a significant increase in relative cell area, an indicator of cell size, was characteristic of cells unable to incorporate 3H‐TdR at both mid‐ and late‐passage, but not at early‐passage levels. Nuclear size also increased significantly with progressive passage level but was not related to proliferative capacity. No significant difference in the area fraction of nucleoli per unit area of nucleus or of mitochondria, Golgi, or lysosomes was seen in either subpopulation at any passage level. Dilated cisternae of rough endoplasmic reticulum in early‐passage cells were seen if cells were harvested with trypsin and fixed either before or after centrifugation, but were not seen in labeled or unlabeled cells from any passage level when cultures were fixed in situ. We conclude that a significant increase in cell size is the only significant morphological change associated with the loss of proliferative capacity of IMR‐90 fibroblasts. Furthermore, our data indicate that there is no accumulation of secondary lysosomes in human diploid fibroblasts during aging in vitro; we therefore cannot support any hypothesis of aging or proliferative decline that is based mechanistically upon this phenomenon.
Effects of indomethacin on preovulatory follicles in immature, superovulated mice
Authors: Downs Stephen M. , Longo Frank J. 
Published: February 2005

AbstractIn order to demonstrate the possible role of prostaglandins in preovulatory follicular development, immature mice superovulated with pregnant mare serum followed 40 hours later by luteinizing hormone (LH) were treated with the prostaglandin‐synthetase inhibitor, indomethacin. Indomethacin (10 mg/kg) injected at varying intervals prior to or following LH inhibited ovulation most effectively when administered within 2 hours of the ovulatory gonadotropin. This inhibition was accompanied by (1) suppression of the morphological changes normally occurring within the follicular wall during preovulatory development and (2) failure of germinal vesicle breakdown (GVBD) in two‐thirds of the follicles examined. When GVBD occurred, indomethacin treatment appeared to delay meiotic maturation. Cumulus tissue was more compact than in control follicles and maintained a close association with the oocyte. These results suggest that alterations in the morphology of the follicle prior to ovulation—specifically, thinning of the apical follicular wall and meiotic maturation—are regulated by prostaglandins.
Variability of ciliary ultrastructure in normal dogs
Authors: Wilsman Norman J. , Farnum Cornelia E. , Reed Debra K. 
Published: February 2005

AbstractThe incidence of abnormal tracheal cilia from each of seven normal healthy dogs was estimated using samples prepared for TEM and SEM from the dorsal, lateral, and ventral aspects of the 3rd, 12th, and 24th tracheal rings. Some samples were demembranated with Triton X‐100 and stained with tannic acid to visualize microtubular protofilaments. From each region of each ring of each dog on which TEM was done, 500 transversely sectioned cilia were observed, 27,000 cilia overall. Abnormal numbers of central microtubules and abnormal numbers of peripheral microtubules occurred in all samples in about 2% of all cilia. Compound cilia were consistently observed in samples from the 3rd ring and were not observed in any samples from the 24th ring. Therefore, before abnormal ciliary ultrastructure may be associated with disease, the rate of occurrence must exceed that in appropriate control individuals. Additionally, compound cilia, which have previously been associated with a variety of diseases, obviously occur in normal individuals; however, their observation may be a function of biopsy site selection.
Interaction of embryonic cell surface and cytoskeleton with extracellular matrix
Authors: Hay Elizabeth D 
Published: February 2005

AbstractEvidence for cell‐matrix in vitro and in the embryo is briefly reviewed, and more detailed observations are presented on the reactions of corneal epithelium and mesenchyme to extracellular matrix (ECM) The basal surface of embryonic corneal epithelium blebs when the underlying ECM is removed If the epithelium is cultured on top of the lens capsule or collagen gel, the basal surface flattens and the cortical cytoskeleton reorganizes to resemble that present in vivo The basal surface also responds to soluble matrix molecules (types I‐IV collagens, laminin, fibronectin), and the cells step up synthesis of corneal stroma as measured by incorporation of proline into collagen When embryonic corneal fibroblasts are placed on top of hydrated gels they tend to burrow into the gel rather than sitting on top as does epithelium When grown inside collagen gels, these mesenchymal cells elongate and the entire cell surface and cytoskeleton organize in response to matrix Stress fibers and ruffling membranes characterize the cells grown on glass When embryonic lens or corneal epithelia are placed within, instead of on top of, collagen gels, they give rise to mesenchyme‐like cells from their apical surfaces In vivo, these epithelia do not give rise to mesenchyme The rules for epithelial‐mesenchymal transformation in vivo are discussed in relation to these observations on cell‐matrix interaction.
Morphology of the pineal complex of the anadromous sea lamprey, Petromyzon marinus L.
Authors: Cole W. C. , Youson J. H. 
Published: February 2005

AbstractThe pineal complex of the anadromous sea lamprey, Petromyzon marinus L., has been examined by light and electron microscopy. It consists of two subunits: a dorsomedial pineal organ, and a ventral, left‐lateral parapineal organ, with both remaining cytologically unaltered throughout the life cycle. However, during metamorphosis there is an increase in the size and a rostral migration of the parapineal organ and a dorsolateral displacement of the pineal nerve tract.The pineal organ is composed of an end bulb, an atrium, and a nerve tract. Two varieties of photoreceptors, termed type I and type II cells, as well as supporting and ganglion cells are present. Supporting cells are ubiquitous, but there are regional variations in the distribution and abundance of the other cell types. Type I cells are a well‐differentiated photoreceptor. Conversely, type II cells exhibit a poorly developed photosensory apparatus but possess some features commensurate with an endocrine activity.The parapineal organ is composed of an end bulb, a ganglion region, and a nerve tract. The end bulb is dominated by type II photoreceptor and supporting cells, whereas type I and ganglion cells are sparse. The parapineal ganglion and nerve tract include neuropil, polymorphic neurons, and ependymal cells.It is concluded that the pineal organ of P. marinus is a structurally well‐developed photosensory and photoneuroendocrine organ that is probably capable of transducing photic stimuli into nervous and endocrine messages to the brain and other organs. In contrast, the parapineal of this lamprey species is a poorly developed organ of regressed or rudimentary structure.
Cellular dynamics of the hormonal and developmental induction of hepatic alpha 2u globulin as demonstrated by immunocytochemistry and specific mRNA monitoring
Authors: Antakly T. , Lynch K. R. , Nakhasi H. L. , Feigelson P. 
Published: February 2005

AbstractThis immunoperoxidase study identifies the hepatocytes that synthesize alpha 2u globulin during male ontogeny and other endocrine states wherein its synthesis is modulated. To correlate biochemical parameters with the immunocytochemistry, alpha 2u globulin mRNA (alpha 2u mRNA) sequences were evaluated by Northern blot hybridization and Rot analysis to a cloned alpha 2u globulin cDNA probe and the functional level of this mRNA measured by cell‐free translation. Alpha 2u globulin and its mRNA were detectable in the liver only after male rats reached puberty. During its developmental and hormonal induction, marked heterogeneity was observed; centrolobular hepatocytes showed the strongest staining, whereas periportal hepatocytes were devoid of, or weakly stained for, this protein. This difference between centrolobular and periportal hepatocytes was enhanced during development. Mature male rats exhibited the strongest staining reaction and the highest levels of hepatic alpha 2u globulin mRNA. Almost all hepatocytes in the adult male were stained; however, centrolobular ones were remarkably more stained than periportal ones. Female rat liver was devoid of this protein and of its mRNA. Following androgen administration to castrated female rats, or hydrocortisone administration to adrenalectomized male rats, the alpha 2u globulin mRNA level as well as the number and intensity of centrolobular alpha‐2u‐globulin‐staining hepatocytes were increased in parallel. Following hypophysectomy, almost no alpha 2u globulin could be localized; likewise its mRNA was undetectable. However, when hypophysectomized adult male rats were treated with growth hormone, testosterone, thyroid hormone, and hydrocortisone, the hepatic immunocytochemical staining as well as the level of alpha 2u globulin mRNA sequences and of functional alpha 2u globulin mRNA, and the in vivo biosynthetic rate of alpha 2u globulin, became comparable to that of intact mature male rats. These studies indicate functional heterogeneity among hepatocytes which seems to be determined by their anatomical location within the hepatic lobule. Furthermore, hormonal and developmental induction of alpha 2u globulin involves both an increase in the number of hepatocytes committed to its synthesis and an increase in the rate of its synthesis in already committed cells. These events are accompanied by a concurrent increase in the hepatic alpha 2u globulin mRNA level.
Isolated guinea pig adrenocortical cells in vitro: Morphology and steroidogenesis in control and ACTH‐treated cultures
Authors: Black V. H. , Mierlak J. , Katz T. , Miao P. , Huima T. , McNamara N. 
Published: February 2005

AbstractIsolated guinea pig adrenocortical cells were maintained in longterm culture in order to perform sequential experiments on the same cell populations. The cells produced fluorogenic steroids, shown by thin‐layer chromatography to be at least aldosterone, cortisol, and corticosterone. In addition, they increased production of these steroids when treated with either ACTH or dibutyryl cyclic AMP. Of particular interest was the fact that cultures treated for the initial 24‐hour culture period with ACTH maintained enhanced levels of secretion for several days in absence of hormone and had an enhanced response to ACTH later in the culture period. Such enhancement of secretion was not seen following early treatment with dibutyryl cyclic AMP. The fine structure of the ACTH‐treated cells was consistent with increased steroidogenesis. They possessed more smooth‐surfaced endoplasmic reticulum, larger mitochondrial cristal surfaces, and larger Golgi complexes than the cells in untreated cultures.
Histologic and fine‐structural anatomy of the adrenorenal portal vessels in the dog
Authors: Katholi Richard E. , Imamura Kikuko , James Thomas N. 
Published: February 2005

AbstractReflex vasoconstriction that occurs in the kidney of the dog can be the result of activation of catecholamine flow reaching the kidney directly from the adrenal medulla via adrenorenal portal vessels. This study was undertaken to learn more about the histologic and fine‐structural anatomy of these unusual vessels. We found that they are thin‐walled vessels (200–500 μm) which are accompanied by many capillaries. These portal vessels have distinctive valves and have sparse, longitudinally arranged musculature which is denser at the base of the valves. The valves in the portal vessels are arranged to permit flow in the direction from the adrenal gland toward the kidney. Smooth muscle at the base of the valve is in close proximity to non‐myelinated nerve fibers, suggesting that the opening of these valves may in part be neurally mediated. These unique anatomical features distinguish the adrenorenal portal vessels from other blood vessels and likely have functional importance in control of the adrenorenal circulation.
Studies on prolonged spermatozoa survival in chiroptera: A morphological examination of storage and clearance of intrauterine and cauda epididymal spermatozoa in the bats Myotis lucifugus and M. velifer
Authors: Krutzsch Philip H. , Crichton Elizabeth G. , Nagle Ray B. 
Published: February 2005

AbstractThe cauda epididymidis, uterine corpus, and cornua and uterotubal junction of Myotis function to retain and preserve normal spermatozoa throughout hibernation. In none of the sites do spermatozoa show features that might account for their extended viability. Spermatozoa stored in the uterus and epididymis show no special orientation toward the epithelium lining these sites, whereas an intimate relationship is established between some sperm and the epithelial cells of the uterotubal junction which might either account for extended postcoital sperm survival or forecast their removal from further participation. Transmission and scanning electron microscopic observations do not disclose any morphological changes in stored luminal spermatozoa. A low rate of phagocytosis of sperm is evident in the female tract during hibernation. However, spermatozoa are evidently not vulnerable to being removed from the storage sites until spring arousal when ovulation occurs. Both uterotubal epithelial cells and phagocytes appear to be involved in the disposal of spermatozoa in the female, whereas epididymal spermatozoa apparently are primarily voided during urination. A mechanism that delays capacitation must underlie the ability of spermatozoa to survive in the female reproductive tract of the hibernating bat.
Histological changes in the articular eminence and mandibular fossa during growth of the rhesus monkey (Macaca mulatta)
Authors: Hinton Robert J. , Carlson David S. 
Published: February 2005

AbstractUnlike the mandibular condyle, the temporal component of the temporomandibular joint (TMJ) has been the object of relatively few investigations concerning its growth and remodeling. This report provides qualitative and quantitative documentation of microanatomical changes in the mandibular fossa and articular eminence during growth of the rhesus monkey (Macaca mulatta). The thickness of the fibrous articular tissue and the presence of cartilage cells in its deeper layers were examined histologically in 43 rhesus monkeys at five maturational levels (neonate, infant, juvenile, adolescent, and young adult). Absolute thickness of the articular tissue increased with maturational level in all areas studied, with the increase somewhat more pronounced on the posterior slope and crest of the articular eminence than in the roof of the mandibular fossa. Relative to condylar size, an increase in articularlayer thickness characterized the first three maturational levels, and was followed by a decrease during adolescent and young‐adult stages. Articular tissue in the fossa roof constituted a steadily decreasing fraction of the total articular‐tissue thickness with age, while relative thickness of the tissue on the posterior slope and crest of the eminence increased with age. These results parallel those obtained for the mandibular condyle, and they are best interpreted to indicate that forces delivered to the joint become directed more anteriorly with age. The overall pattern of topographical variation in articular‐tissue thickness and cartilage‐cell distribution suggests that greater loading of the lateral aspect of the TMJ, postulated in the human TMJ by various workers, may not be as pronounced in the monkey.