bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluctuations in follicular structures of rat thyroid glands during 24 hours: Fine structural and morphometric studies
Authors: Uchiyama Yasuo , Oomiya Akemi , Murakami Gen 
Published: February 2005

AbstractThe thyroid follicles of adult male Wistar rats were examined at six evenly spaced times over 24 hr with a morphometric technique. Follicular structures were subjected to distinct variations during 24 hr, with respect to volume and numerical densities of follicles in the thyroid gland, and diameters, volumes, cell numbers, and luminal surface areas of individual follicles. Variations in follicular structures were divided into two phases: a large follicular phase at 1200, 1600, and 2000 hr and a small follicular phase at the other times. Although volume densities of follicles in the gland varied with a small amplitude, diameters, volumes, and cell numbers of individual follicles exhibited distinct fluctuations during 24 hr. Numerical densities of follicles in the gland changed distinctly during the small follicular phase as well. Degenerating follicular cells appeared in the follicular lumen especially at 1600 hr. No mitotic follicular cells were found throughout the experiment. Furthermore, one to three follicular cells of two adjacent follicles were often in contact with each other at 0400, 0800, and 1200 hr, and these follicles were lined by the common basement membranes. These results suggest that the variations in follicular structures during the small follicular phase occur in the form of follicle separation and fusion. Moreover, the morphological and morphometric variations in follicles reflect those in subcellular structures of follicular cells previously reported by us.
Capillary permeability in the pancreas and colon: Restriction of exogenous and endogenous molecules by fenestrated endothelia
Authors: Hart Timothy K. , Pino Richard M. 
Published: February 2005

AbstractThe permeability properties of fenestrated capillaries in the colon and exocrine and endocrine pancreas to exogenous and endogenous molecules were examined. The exogenous tracers horseradish peroxidase (Einstein‐Stokes radius [ESR], 3.0 nm), hemoglobin (ESR, 3.2 nm), and ferritin (ESR, 6.1 nm) were injected intravenously and allowed to circulate for 5–90 min. Tissues were removed and processed for cytochemical or standard electron microscopic examination. The endogenous plasma proteins albumin (ESR, 3.5 nm) and IgG (ESR, 5.5 nm) were localized by immunocytochemistry using the protein A‐gold technique. All vessels examined were permeable to HRP in less than 5 min. In contrast, these vessels were restrictive to the slightly larger hemoglobin molecule (60‐min circulation) and to ferritin (90‐min circulation). Capillaries in the exocrine and endrocrine pancreas were restrictive to albumin and IgG. These results demonstrate the presence of fenestrated capillary beds, in addition to the choriocapillaris, that are restrictive to molecules with ESR ≥ 3.2 nm. Capillaries in the mucosa of the colon were restrictive to hemoglobin and ferritin but did not restrict albumin or IgG. This indicates that these vessels are of the permeable type. However, the rate of transendothelial movement of molecules is slower than that of other permeable vessels, such as in the ileo‐jejunum. This study has provided further evidence for the existence of fenestrated endothelia that are restrictive to exogenous and/or endogenous molecules.
Differentiation of tracheal epithelium during fetal lung maturation in the rhesus monkey Macaca mulatta
Authors: Plopper Charles G. , Alley Janice L. , Weir Alison J. 
Published: February 2005

AbstractOf the eight categories of epithelial cells identified in pulmonary conducting airways, four are found in the trachea of adult primates: basal, mucous goblet, intermediate, and ciliated cells. While their ultrastructure is well characterized, little is understood about their origin or differentiation. This study describes the pattern of differentiation of the tracheal luminal epithelium in a species of nonhuman primate, the rhesus monkey, Macaca mulatta. Tracheas of 57 fetal and postnatal rhesus were fixed with glutaraldehyde/paraformaldehyde: ten at 29–54 days gestational age (GA), ten at 59–80 days GA (pseudoglandular stage), sixteen at 82–130 days GA (canalicular stage), ten at 141–168 days GA (saccular stage), eight at 1–134 days postnatal, and three adults (2 yr 11 months to 11 yr 11 months). Slices taken proximal to the carina were processed for electron microscopy by a selective embedding procedure. In the youngest fetuses, essentially one population of cells lined the tracheal epithelial surface. These cells were columnar in shape with a central nucleus, few organelles, and large amounts of cytoplasmic glycogen. At 46 days GA, ciliated cells were observed on the membranous side of the trachea. Some nonciliated cells had concentrations of organelles in the most apical portion of their cytoplasm. At 59 days GA, membrane‐bound cored granules were intermixed with organelles in the apices of some glycogen‐filled cells. They were observed first on the cartilaginous side. Between 59 and 100 days GA, a large number of cell forms which appeared to be transitional between ciliated, secretory, basal, and undifferentiated cells were present. These included ciliated cells with electron‐lucent inclusions resembling mucous granules. Mucous secretory cells were more numerous and had more granules and less glycogen in older fetuses. By 105 days GA, few of the secretory cells had significant amounts of glycogen and the cytoplasm was condensed. Secretory granules were very abundant in some cells and minimal in others. The Golgi apparatus was prominent. In animals 120 days GA and older, small mucous granule cells and basal cells resembling these cells in adults were present. By 134 days postnatal age, the epithelium resembled that in adults. We conclude that (1) most of the differentiation of tracheal epithelium in the rhesus monkey occurs prior to birth; (2) the cells differentiate in the following sequences: ciliated, mucous goblet, small mucous granule, basal; and (3) basal and small mucous granule cells do not play a role in ciliated and mucous cell formation in the fetus.
Architecture of the masticatory apparatus in eastern raccoons (Procyon lotor lotor)
Authors: Gorniak Gerard C. 
Published: February 2005

AbstractThe structure and function of the masticatory apparatus of raccoons resemble those found in carnivores. In this study, the architecture of the skull, dentition, and masticatory apparatus is described, and a model is proposed that suggests a mechanism used by raccoons to reduce different foods. The model suggests that (1) jaw movements are similar to those of cats, (2) the posterior regions of the superficial and deep parts of the temporalis and the anterior region of the medial pterygoid generate horizontal jaw movements, and (3) the anterior portions of the superficial and deep temporalis as well as portions of the masseteric complex generate vertical closing movement. The distributions of slow, fast fatigable, and fast fatigue‐resistant fibers for the temporalis and masseteric complex are related to the possible actions of these muscles during mastication, as are the regional cross‐sectional areas of the masticatory muscles.
Immunochemical and cytochemical studies of relaxin‐containing cells in the guinea pig uterus
Authors: Larkin Lynn H. , Renegar Randall H. 
Published: February 2005

AbstractUteri and ovaries from cycling, pregnant, and lactating guinea pigs were studied for immunolocalization of relaxin with the light microscope. Endometrial gland cells (EGC) from the same group of animals were examined in the electron microscope for the presence of secretory granules. Those EGC that exhibited high numbers of granules were stained either for relaxin with the protein A colloidal gold method or for carbohydrate with the thiocarbohydrazide technique. Relaxin was found in EGC from middle and late pregnant animals but was not detected in ovaries or uteri from cycling animals. While cytoplasmic granules were noted in most EGC from cycling animals examined, the number of granules was greatest in uteri from estrus and proestrus animals. Granules in EGC from estrus animals contained a carbohydrate‐rich material but did not contain relaxin. Endometrial gland cells from animals in early to middle stages of pregnancy (days 15 and 30) contained limited numbers of granules, almost all of which contained carbohydrate. At day 45 of pregnancy, EGC containing many granules were noted. The majority of granules contained relaxin; however, a significant number of EGC contained carbohydrate‐rich granules. Infrequently, EGC were noted that contained two populations of granules, and these two populations were assumed to be made up of relaxin‐containing and carbohydrate‐rich granules. EGC from animals on day 60 of pregnancy typically contained granules, and the majority of these contained relaxin. Carbohydrate‐rich granules were observed in EGC of the day 60 animals but were smaller in diameter and were noted in much lower numbers than the relaxin‐containing granules. Endometrial gland cells from lactating animals infrequently contained granules. These studies are consistent with the hypothesis that the uterus is the primary source of relaxin in the guinea pig and that relaxin plays an important role in pregnancy and parturition of this species. The observations implicate endometrial glands and their products in the physiology of the cycling animal as well as the pregnant and parturient animal.
Early development of the hypoglossal nerve in the chick embryo as observed by the whole‐mount nerve staining method
Authors: Kuratani Shigeru , Tanaka Shigenori , Ishikawa Yuji , Zukeran Chosei 
Published: February 2005

AbstractThe developmental morphology of the hypoglossal nerve and associated structures were studied in the chick embryo (Hamburger and Hamilton stages 16‐27) stained by the immunohistochemical technique. Ventral rootlets of the occipital nerves, including 01, were seen at stage 16. The distal ends of these nerves anastomosed to form the hypoglossal nerve at stage 20. At stage 23, four occipital and the first three cervical nerves were observed to be involved. The transient contribution of C3 at this stage seemed to be correlated with the formation of the longitudinal anastomosis of the distal end of the spinal nerves which begins around stage 23. The anterior hypoglossal roots appeared between 01 and the abducens nerve at stage 20. These rootlets were observed to arise as the rostral continuation of the occipital sequence and were found to be arranged in a straight line from 01 to the abducens nerve. The recurrent branch of the abducens was also observed. The posterior end of the ganglion crest produced dorsal root ganglion (DRG)‐like structures transiently at the level of C2, and sometimes at the level of C1 also. The ganglion crest developed descending processes in the occipital region seemingly related to the spinal dorsal root formation. These phenomena seemed to represent the potential of the ganglion crest to produce the spinal nerve components which are depressed in the occipital region.
Epicardial formation in embryonic chick heart: Computer‐aided reconstruction, scanning, and transmission electron microscopic studies
Authors: Hiruma Tamiko , Hirakow Reiji 
Published: February 2005

AbstractEpicardial formation in the embryonic chick heart from initial to final stages was revealed by means of computer‐aided reconstructions based on serial resin sections for light microscopy, with further detailed observations using scanning and transmission electron microscopy. The origin of the epicardium was recognized as protrusions of mesothelial cell clusters on the right side of the external surface of the sinus venosus at 23 somites (stage 14+). These protrusions elongated to give rise to several villous processes, the tips of which eventually touched the dorsal wall of the embryonic heart at 30 somites (stage 17). Originating from these adhesion sites, mesothelial cells spread gradually onto myocardial cells in all directions to form a monolayered sheetlike cover. Thus, by stage 23, the ventricle was completely overlaid with epicardium, and blood‐island‐like structures appeared within the subepicardial layer. The atrium was not enveloped by epicardium until stage 25, and the extreme distal end of the bulbus cordis was reached by the advancing epicardium at stage 27. A chronological table of epicardial formation in the chick heart is presented.
Palmar‐digital arterial networks in fifty pairs of human fetal hands: Arteriographic models for clinical consideration
Authors: Maher William P. 
Published: February 2005

AbstractArterial networks in 50 pairs of human fetal hands, made visible by perfusion with radiopaque media, were compared between right and left hands. The imaged primary arterial networks in the fetal hands were also compared with those in adult human and rhesus monkey hands. It was found that superficial arch configurations and their primary ramifications are bilaterally similar in human fetal hands. The configurations of the primary arterial networks are established very early in prenatal growth and may be maintained into adulthood. The similarities in the arterial network arrangements between fetal human and rhesus monkey hands suggest that the rhesus monkey hand could provide and appropriate model for studies of surgical neurovascular anastomosis.
Flow cytometric DNA analysis of corneal epithelium
Authors: Burns E. Robert , Roberson Michael C. , Brown Michael F. , Shock John P. , Pipkin James L. , Hinson William G. , Anson Jeanne F. 
Published: February 2005

AbstractWe have modified an existing technique in order to perform DNA analysi by flow cytometry (FCM) of corneal epithelium from the mouse, rat, chicken, rabbit, and human. This protocol permitted an investigation of human corneal scrapings from several categories: normal, aphakic bullous keratopathy (ABK), keratoconus (KC), Fuch's dystrophy, edema, epithelial dysplasia, and lipid degeneration. No abnormal characteristic cell‐kinetic profile was detected when averaged DNA histograms were compared statsitically between the normal and either ABK, KC, edema, or Fuch's dystrophy groups. Abnormal DNA histograms were recorded for cell samples that were taken (1) from three individuals who had epithelial dysplasia and (2) from one individual diagnosed with lipid degeneration. The former condition was characterized by histograms that had a subpopulation of cells with an aneuploid amont of DNA or had higher than normal percentages of cells in the S and G2 + M phases of the cell cycle. Corneal cells from the patient who had lipid degeneration had an abnormally high percentage of cells in the G2 + M phases of the cell cycle. The availability of accurate DNA flow cytometric analysis of corneal epithelium allows further studies on this issue from both experimental and clinical situations.
Angiology of the brain of the baboon Papio ursinus, the vervet monkey Cercopithecus pygerithrus, and the bushbaby Galago senegalensis
Authors: Lake A. R. , Van Niekerk I. J. M. , Le Roux C. G. J. , Trevor‐Jones T. R. , De Wet P. D. 
Published: February 2005

AbstractThe investigation was undertaken to compare the blood supply and venous drainage of the brain of the baboon P. ursinus, the vervet monkey C. pygerithrus, and the bushbaby G. senegalensis with that of man, because these animals are extensively used as research models.The blood supply of the three primates was found to be similar in each case. Like man they have a complete circulus arteriosus; but they have a single anterior cerebral artery, whereas man has paired anterior cerebral arteries. The arterial supply to the cerebellum in the primates is similar to that in man, the main difference being a “common inferior cerebellar artery” which bifurcates to form the anterior inferior cerebellar and posterior inferior cerebellar arteries. In man, these arteries arise separately from the basilar artery and vertebral arteries, respectively.The dural venous drainage was also found to be similar in these primates but was far more extensive than in man. The primates have additional sinuses–the more important of these being the “basisphenoid sinus” and the petrosquamous sinus. The former drains the basilar sinus and is itself drained via the vertebral venous plexus and internal jugular vein. The latter drains via the petrosquamous foramen into the retromandibular vein. The petrosquamous sinus has a rostral extension which drains through the foramen ovale and two lateral and medial connecting sinuses which drain the cavernous and basilar sinuses, respectively. These sinuses are not found in man.
Anatomical studies of the coronary system in elasmobranchs: I. Coronary arteries in lamnoid sharks
Authors: De Andrés A. V. , Muñoz‐chápuli R. , Sans‐Coma V. , García‐Garrido L. 
Published: February 2005

AbstractA study of the anatomy of coronary arteries has been done in five shark species of the order Lamniformes: Isurus oxyrinchus, Isurus paucus, Lamna nasus, Alopias superciliosus, and Alopias vulpinus. The study, which included 26 specimens, was carried out with the injection‐corrosion technique, obtaining internal casts of the main trunks and coronary arterial branches.The results have shown a high degree of constancy in the coronary patterns in all species and a number of general features common to all of them, except for Alopias vulpinus. In this species, a mesh‐like ventricular pattern of intramyocardial vessels was found instead of subepicardial ventricular coronary branches with a definite patern.It was also shown that there is a wide range of variation among the species regarding the relative importance of the dorsal and ventral coronary trunks. Thus, Isurus oxyrinchus showed a clear predominance of the ventral coronary trunk, whereas in Alopias superciliosus, most of the ventricle was supplied by branches derived from the dorsal coronary trunk.
Uterine fibronectin mRNA content and localization are modulated during implantation
Authors: Rider Virginia , Carlone Diana L. , Witrock Debra , Cai Cindy , Oliver Noelynn 
Published: February 2005

AbstractFibronectin mRNA and protein content were examined during embryonic implantation in the rat uterus. Content of total fibronectin mRNA at day 6 of pregnancy increased relative to the non‐pregnant uterus. In contrast, fibronectin protein content of the subepithelial stroma was relatively decreased except in the region directly surrounding the lumen, and this fibronectin immunoreactivity was sensitive to hyaluronidase treatment. These changes are likely to reflect the degradation and subsequent remodeling of the previously stable uterine extracellular matrix in preparation for embryonic implantation. A+,B‐,V+ fibronectin mRNAs were present in both the non‐pregnant and day 6 pregnant uterus with increased content of A+ and V+ fibronectin mRNAs in the latter. A+ fibronectin mRNA was distributed throughout the endometrial stroma of the non‐pregnant uterus and content of the subepithelial stroma increased by day 4 of pregnancy, coincident with progesterone action on the endometrium. On day 6 of pregnancy, fibronectin mRNAs encoding the V95 and A regions were preferentially localized to the mesometrial zone of the subepithelial stroma. Accumulation of these mRNA splicing variants at the mesometrial zone was dependent upon decidualization, but the embryo was not required. Thus, there are two major changes in uterine fibronectin gene expression as a result of pregnancy: increased fibronectin mRNA content and mesometrial localization. These changes suggest a key function for fibronectin in implantation and imply the operation of a regulatory program of fibronectin gene expression which depends on hormonal sensitization and a nidatory stimulus. © 1992 Wiley‐liss, Inc.
Stripe selection: An intrinsic property of some pattern‐forming models with nonlinear dynamics
Authors: Lyons Michael J. , Harrison Lionel G. 
Published: February 2005

AbstractIn two‐dimensional pattern formation, the genesis of striped rather than spotted patterns may involve preexisting spatial asymmetries, such as unidirectional gradients or asymmetric shape of the pattern‐forming domain. In the absence of such asymmetries, some kinds of nonlinear dynamics still lead to striped rather than spotted patterns. We have studied the latter effect both by extensive computer experiments on a range of nonlinear models and by mathematical analysis. We conclude that, when the dynamic equations are written in terms of departure from the unpatterned state, the presence of nonlinearities which are odd functions of these departures (e.g., cubic terms) together with absence of even nonlinearities (e.g., quadratic terms) ensures stripe formation. In computer experiments, we have studied the dynamics of two‐morphogen reaction‐diffusion models. The mathematical analysis presented in the Appendix shows that the same property exists in more generalized models for pattern formation in the primary visual cortex. © 1993 Wiley‐Liss, Inc.
Role of growth factors in catecholaminergic expression by neural crest cells: In vitro effects of transforming growth factor beta1
Authors: Howard Marthe J. , Gershon Michael D. 
Published: February 2005

AbstractThe differentiation of neural crest cells into catecholaminergic neurons is dependent upon both intrinsic properties and signals from the embryonic microenvironment. In tissue culture, the development of catecholaminergic traits is dependent upon factors present in chick embryo extract (CEE). This dependency suggests that soluble growth factors affect catecholaminergic differentiation in vivo. We have studied the role of CEE‐derived factors and the potentially related influence of characterized growth factors on catecholaminergic phenotypic expression in avian neural crest cells. In this report, we show that CEE‐derived factors and transforming growth factor beta1 (TGF‐β1) differentially influence catecholaminergic phenotypic expression as well as melanogenesis. TGF‐β1 substituted for CEE‐derived factors and supported the in vitro differentiation of tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DBH) immunoreactivities, as well as catecholamine biosynthesis and storage. Differentiation of catecholaminergic cells was dependent on factors present in 10% CEE during the first 1–4 days in culture suggesting an initial critical period for exposure. One day of initial exposure to either CEE‐derived factors or TGF‐β1 was sufficient to support the subsequent expression of catecholaminergic phenotypic characteristics. The time course of responsiveness to TGF‐β1 was different than for CEE‐derived factors. Neural crest cells remain responsive to TGF‐β1 for at least 5 days, which is past the critical period for CEE‐derived factors. Bioassay of CEE shows that endogenous levels of TGF‐β are less than or equal to 0.5 ng/ml. Immunoprecipitation of TGF‐β from CEE or blockade by neutralizing antibodies did not result in a loss of catecholaminergic differentiation by neural crest cells. Although CEE supports melanogenesis under all of the growth conditions tested, TGF‐β1 was found to be inhibitory. © 1993 wiley‐Liss, Inc.