bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonimmune‐mediated phagocytosis by “premedullary” lung macrophages: Effects of concanavalin A, tuftsin, and macrophage‐inhibitory peptide
Authors: Sorokin Sergei P. , Hoyt Richard F. , McNelly Nancy A.
Published: February 2005

Free cells arising in organ‐cultured embryonic rat and hamster lungs share ultrastructural, lysosomal enzyme, and cell membrane properties with typical alveolar macrophages, expressing the developmental potential of the earliestmacrophage precursors resident in the lungs. In the lung culture environment cell proliferation is supported and macrophage attributes are developed despite absence of lymphocytes from the system. We have shown previously that among these attributs, the cells respond with increased phagocytosis of erythrocytes if these are opsonized with immunoglobulin G. Attention has now been turned to the question of nonimmune‐mediated phagocytosis by the same population. Living macrophages that emerged from lung cultures bound rhodamine‐coupled soybean and wheat germ agglutinins to a greater degree than concanavalin A (Con A), which nevertheless promoted lateral translocation of occupied receptors in the cell membrane. Emerged cells also phagocytosed living bacteria and native yeast cells (Y). The percentage of macrophages ingesting 3 or more yeast cells increased 400 (hamsters) to 500% (rats) when yeast was preincubated with Con A (200 μg/ml). Pretreatment of macrophages with Tuftsin (100 μM) enhanced uptake of Y by 100 (hamster) to 200% (rat). Pretreatment of macrophages with macrophage‐inhibitory peptide (500 μM) appeared to inhibit phagocytosis of Y by 60% in hamsters but had no significant effect on cells from rat lung cultures.
Co‐localization pattern of growth hormone (GH) and prolactin (PRL) within the anterior pituitary cells in the female rat and female musk shrew
Authors: Ishibashi Toshiko , Shino Masataka
Published: February 2005

By a double immunocytochemical labeling procedure, using the protein A‐gold method combined with electron microscopy, the co‐localization pattern of growth hormone (GH) and prolactin (PRL) was detected in the anterior pituitary cells of female rats and female musk shrews. Two types of co‐localization of GH and PRL were demonstrated. First, GH‐ and PRL‐containing secretory granules were intermixed within closely aggregated and interdigitated cell clusters that were composed of GH and PRL cells. This phenomenon was characteristically seen in pregnant rats and pregnant musk shrews. Therefore, the occurrence of an inter‐mixture of GH and PRL granules might be related to an enhanced cellular function for PRL synthesis.

In another pattern of co‐localization of GH and PRL, both hormones were co‐packaged in the same secretory granules within a single cell. Such cells were scarce, small, irregularly shaped, and observed only in pregnant rats. These mixed GH‐PRL cells contained not only mixed GH‐PRL granules but also granules containing only GH or PRL. This suggests that these bihormonal cells are able to synthesize, synchronously or asynchronously, GH and PRL. Furthermore, granule extrusion from the mixed cells was clearly shown in this study. It seems likely that the mixed GH‐PRL cells reveal active cellular function in the pituitary gland of the pregnant rat.
Neurulation in the mouse: Manner and timing of neural tube closure
Authors: Sakai Yoshio
Published: February 2005

The manner and timing of neural fold fusion in primary neurulation were studied in 1,575 normal ICR mouse embryos by using binocular dissecting, light, and scanning electron microscopy.

The initial fusion of apposing neural folds occurred at the level of the intermediate point between the third and fourth somites (i.e., in the caudal myelencephalon) and proceeded both rostrally and caudally. A second fusion occurred at what was originally the rostral end of the neural plate and proceeded rostrodorsally. A third fusion occurred in the caudal diencephalon and proceeded both rostrally and caudally. This was followed by complete closure of the telencephalic neuropore at the midpoint of the telencephalic roof and then complete closure of the metencephalic neuropore at the rostral part of the metencephalic roof. A fourth fusion occurred at what was originally the caudal end of the neural plate and proceeded rostrally. Finally, the caudal neuropore completely closed at the level of the caudal end of the future 33rd somite.
Neural crest ablation does not alter pulmonary vein development in the chick embryo
Authors: Phillips Marvin T. , Waldo Karen , Kirby Margaret L.
Published: February 2005

Cranial neural crest, which extends from the mid‐diencephalon to somite five, plays an integral role in development of pharyngeal arch derivatives and supplies mesenchyme to the aortic arch arteries. Neural crest cells in pharyngeal arches three, four, and six migrate to the heart and are involved in aorticopul monary and conotruncal septation. Ablation of the “cardiac” neural crest cells in chick embryos results in a variety of outflow tract anomalies, including persistent truncus arteriosus. Although other studies have shown the importance of the neural crest in the development of the cardiac outflow tract, the role of neural crest in venous development has not been established. This investigation evaluates the effect of cardiac neural crest ablation on the morphological development of the pulmonary vein. The presence of the pulmonary vein was confirmed initially at early stage 15 using histological sections and computer reconstructions of serially sectioned, normal embryos. India ink injections demonstrated a complete, patent pulmonary circuit at stage 18. Cardiac neural crest was ablated at stages 8–10. Operated, sham‐operated, and control embryos were sacrificed at incubation day 11, and acrylic plastic casts prepared of the intravascular compartment. In experimental embryos with persistent truncus arteriosus, there were no morphological differences in the pulmonary veins, compared with shams and controls. These data indicate that the lesions of the cardiac neural crest have little morphological impact on pulmonary vein development. It is concluded that alterations in the cardiac neural crest are not involved in venous anomalies such as cor triatriatum and total or partial anomalous pulmonary venous return.
Teratogenic antibodies are directed against a coated‐pit glycoprotein
Authors: Leung Christopher C. K. , Cheewatrakoolpong Boonlert , Yan Cai‐Lou
Published: February 2005

It has been well established that heterologous antibodies against certain tissue components may cause congenital abnormalities when injected into pregnant rats during the critical period of organogenesis. A glycoprotein antigen (gp340) of rat renal proximal tubules was isolated (C.C.K. Leung: (J. Exp. Med., 156:372–384, 1982); antibodies against gp340 were teratogenic.

Indirect colloidal gold immunocytochemical method was utilized to study the ultrastructural localization of gp340. For comparative studies, both preembedding and postembedding immunostaining procedures were used. The results indicate that gp340 is a resident of coated pits and possibly also of coated vesicles of the rat renal proximal tubules and visceral yolk‐sac (VYS) endodermal cells. It appears that gp340 may also be associated with the microvilli and some as‐yet‐unidentified cytoplasmic structures of the same tissues. However, gp340 is absent on the epithelium of the small intestine.

It is hypothesized that the teratogenic antibodies may interact with gp340 on the coated pits and interfere with receptor‐mediated endocytosis, causing yolk‐sac placenta dysfunction which in turn causes abnormal embryonic development.
Scanning and transmission electron microscopic study of the tracheal air sac system in a grasshopper Chrotogonus senegalensis (Kraus)—Orthoptera: Acrididae: Pyrogomorphinae
Authors: Maina J. N.
Published: February 2005

The morphology of the trachea‐air sac system in a species of grasshopper Chrotogonus senegalensis has been studied by using scanning and transmission electron microscopes. Capacious air sacs were formed as dilatations along the primary tracheal trunks. Narrower secondary trachea arose either directly from the primary trachea that bypassed the air sacs or from the air sacs themselves. At or close to the organ or tissue supplied with air, the secondary trachea gave rise to the notably smaller tertiary trachea that penetrated the tissue, giving rise terminally to the extremely small tracheoles that indent some cells. The trachea and the air sacs were basically made up of an inner cuticular lining, helical taenidial rings, and an overlying epithelial cell cover. The air sacs may be important in efficient ventilation of the respiratory system. The supply of air directly to the tissue cells was viewed as an exemplary efficient design when compared to that prevailing in the nontracheate air‐breathing animals, where the vascular system is interposed between the respiratory organ and the target tissue cells. A similarity in the general morphological design of the insect and avian respiratory systems has been observed, mainly in respect to the presence of the air sacs and that of the respiratory shunts. This, together with the reported functional features like the unidirectional mode of ventilation, has been interpreted as a classic case of structural and functional convergent evolution leading to the evolution of similar and comparably efficient respiratory systems capable of providing the large amount of oxygen demanded by flight.
Immunofluorescent localization of desmin and vimentin in developing cardiac muscle of Syrian hamster
Authors: Osinska Hanna E. , Lemanski Larry F.
Published: February 2005

The distributions of desmin and vimentin were examined in frozen sections of cardiac muscle from embryonic, newborn, and adult Syrian hamster by using immunofluorescent methods. Frozen sections of newborn and adult skeletal muscle were used for comparison. Cardiac myocytes from day 9 in utero embryos already show a clear association of desmin with the sarcomeric myofibrils. In newborn hearts, desmin is localized in the myofibrillar Z‐line areas as well as in the peripheral cytoplasm of the cell. Three days after birth, desmin is associated with the intercalated discs. Thus, in adult cardiac muscle, desmin is present in both Z‐bands and intercalated discs. Skeletal muscle of newborn and adult hamster also contains desmin associated with the Z‐lines of myofibrils. Vimentin is associated with the myofibrils of day 9 in utero cardiac muscle cells. The protein remains associated with the myofibrillar Z‐lines in the newborns and adults. No detectable staining for vimentin was observed in newborn or adult hamster skeletal muscle. The existence of vimentin as well as desmin in differentiated cardiac muscle may be a consequence of the somewhat more epithelial‐like nature of cardiac cells as compared to skeletal muscle syncitia.
Pathways between lymph vessels and sinuses in lymph nodes: A study in horses
Authors: Heath Trevor J. , Perkins Nigel R.
Published: February 2005

The pathways through which lymph flows from terminal afferent lymphatics to the lymph sinuses, and from the sinuses to initial efferent lymphatics, were studied in horse lymph nodes by using Microfil casts and electron microscopy.

Terminal afferent lymphatics are continuous with the subcapsular sinus through oval holes, about 3 μm wide, along their length, and through larger openings near their end. Other terminal afferents penetrate into the node within trabeculae and are supported by processes across the lumen. They connect with trabecular and medullary sinuses through oval or round holes, generally 20–30 μm across. Some of these have processes, similar to the luminal strands of the adjacent sinuses, extending across them, apparently providing reinforcement.

Initial efferent lymphatics receive lymph from medullary sinuses through holes which are similar to those in afferent lymphatics, though more common, especially near the origin of the vessel. Initial efferents within the medulla appear to be supported by the luminal strands of the surrounding medullary sinuses. It seems likely that these strands, like the trabeculae which surround the penetrating afferent lymphatics, may help to keep the lymphatic vessels open as the node swells while draining an area of infection.
Muscle receptors: Content of some of the extrinsic and intrinsic muscles of the larynx in the bonnet monkey (Macaca radiata)
Authors: Raman R. , Devanandan M. S.
Published: February 2005

The number of muscle receptors and in particular the muscle spindle content of some of the intrinsic and extrinsic laryngeal muscles was evaluated, using bonnet monkeys (Macaca radiata). The technique of Barker and Ip [J. Physiol. (Lond) 169:73–74, 1963] was used to stain the muscle receptors. The results indicate that the intrinsic laryngeal muscles were devoid of muscle spindles. The extrinsic laryngeal muscles that were examined contain muscle spindles, though their density is less than that reported in the spindle‐rich muscles like the rotators of the head and some of the intrinsic muscles of the hand (Cooper in: Structure and Function of Muscle, Vol. I, G.H. Bourne, ed, Academic Press, New York and London, 1960).
Oviductal, not oviducal
Authors: Smith Hobart M. , Preston Michael J. , Jones Richard E.
Published: February 2005

Both etymologically and in literal meaning the term “oviductal” is overwhelmingly preferable to “oviducal.”
Mechanism of calcification: Role of collagen fibrils and collagen‐phosphoprotein complexes in vitro and in vivo
Authors: Glimcher Melvin J.
Published: February 2005

Samples of decalcified chicken bone together with varying concentrations of phosphoproteins from bone or egg yolk (phosvitin) were used in vitro as heterogenous nucleators for the induction of Ca‐P apatite crystals. The lag time between exposure of the collagen‐phosphoprotein complexes and the time nucleation of crystals occurred decreased as the concentration of Ser(P) and Thr(P) increased. Enzymatic cleavage of the phosphate groups by wheat germ and phosphatase reversed this effort, indicating that the phosphate group per se principally facilitated the nucleation of Ca‐P crystals by the phosphoprotein complex and collagen.
Structure and function of enamel gene products
Authors: Deutsch Dan
Published: February 2005

The present paper reviews the main features of amelogenin and enamelin biochemistry, molecular biology, structural and ultrastructural localization, and immunology. It also examines recent studies concerning the origin, chemical characterization, suggested role, and participation of these two major classes of extracellular developing enamel matrix proteins in the complex process of “matrix‐mediated” mineralization.
Isomyosin expression patterns during rat heart morphogenesis: An immunohistochemical study
Authors: De Groot Imelda J. M. , Lamers Wouter H. , Moorman Antoon F. M.
Published: February 2005

An immunohistochemical study of cardiac alpha and beta myosin heavy chain (MHC) expression during rat heart morphogenesis was performed. In tubular hearts (embryonic days, ED10–11) coexpression of both cardiac alpha and beta MHC was found throughout the heart, except for the left free wall of the atrium, where only cardiac alpha MHC is detected. A transition of coexpression to single expression of either cardiac alpha or beta MHC begins at the same time in both atria and ventricles but requires a longer time for completion in the ventricules; in the atria transition takes place during the period ED 12–13 and in the ventricles during ED12–15. Furthermore, expression of cardiac alpha and beta MHC was detected in the sinus venosus, and cardiac alpha MHC expression was detected in the pulmonary veins.

A comparison of the results obtained in chicken embryos revealed that in tubular hearts the expression pattern is similar, whereas in later developmental stages two major differences were observed: (1) transition of coexpression to single expression in rat ventricles appears to take a longer developmental period; (2) the persistence of areas of coexpression in the sinoatrial junction, dorsal mesocardium, atrioventricular junction, and outflow tract, as found in the chicken embryo in later developmental stages, is not found in the rat heart.
Catecholamine‐containing, dopamine‐beta‐hydroxylase‐immunoreactive perivascular nerve specializations in the rat kidney
Authors: Knight D. S. , Beal J. A. , Fabre R. D. , Henderson R. J.
Published: February 2005

Fluorescence histochemical visualization of catecholamines and immunolabeling of dopamine beta hydroxylase (DBH) were employed to study noradrenergic nerve terminals and perivascular nerve specializations in the rat kidney. Plexuses of catecholamine‐containing and dopamine‐beta‐hydroxylase‐immunoreactive nerves innervate the intrarenal arterial tree and larger intrarenal veins. Some perivascular nerve bundles have specialized segments composed of clusters of axonal enlargements that are immunoreactive for DBH and fluoresce intensely in ultraviolet light after fixation in a solution of formaldehyde and glutaraldehyde or treatment with glyoxylic acid. No fluorescent neural structures were found in denervated rat kidney sections treated with glyoxylic acid. Many such structures are associated with arteriolar branches of interlobar, arcuate, and interlobular arteries and are composed, in part, of axonal enlargements that contain mitochondria, microtubules, and one or more clusters of synaptic vesicles. These perivascular nerve specializations may be sites of axoaxonal interactions between noradrenergic axons or between these axons and other types of autonomic or sensory axons. The synaptic vesicles evidently store large amounts of catecholamine, but there is no evidence whether it is released into the surrounding tissue. These structures may be involved in changes in intrarenal innervation patterns which may occur as the rat ages. Regardless of the autonomic or sensory nature of intrarenal neural structures, close association of most such structures with arterioles suggests some neurovascular interaction.
Effects of indomethacin on spacing of conceptuses within the uterine horn and on fetal and placental growth in the rat
Authors: Wellstead Jennifer R. , Bruce Neville W. , Rahima Ali
Published: February 2005

In the rat, as in most other polytocous species, fetuses tend to be relatively evenly spaced along the uterine horn, porhaps to minimize possible effects of local overcrowding on placental function and fetal growth. Here we administered 2 mg of indomethacin, in split doses on day 5 of gestation, in an attempt to disturb evenness of spacing and so reveal local overcrowding effects, if any. The effects on spacing, expressed as the coefficient of deviation of distances between neighboring implants (CVd%) and correlations between fetal and placental weights and distance to neighbors, was examined on day 16 and day 22 of gestation to cover the period of rapid fetal growth. Indomethacin markedly affected evenness of spacing; at day 16, CVd% increased from a control value of 19.2 to 50.8% and at day 22 from 27.5 to 41.2%. Despite the increased variability of spacing and consequent local crowding, including examples of conjoined placentas in the treated rats, there was no evidence that these local factors affected placental growth or weight of individual fetuses. Indomethacin, however, had a general effect on placental and fetal growth. At day 16, mean fetal weights were retarded but by day 22 had caught up to those of control litters, and this was accompanied by significant placental hypertrophy. Collectively, these results show that the uterus has sufficient reserve to cope with relatively uneven spacing of fetuses and have provided a model for examining catch‐up growth of fetuses and accompanying placental changes.
Developmental competency in spinal nerve fiber extension on a reconstituted basement‐membrane‐like matrix
Authors: Liebig Veronica , Pollack Emanuel D.
Published: February 2005

Nerve fibers readily extend from larval frog spinal cord explants when cultured on a commercially available reconstituted basement‐membrane‐like matrix derived from the EHS mouse sarcoma. This superior, naturally derived substratum enables the in vitro development of complex neuritic arrays with long survival times in a defined medium, thus permitting the detailed analysis of spontaneous and target‐mediated neuritogenesis.
Ultrastructural observation of the trans‐Golgi associated plate‐like cisterna in the secretory cells of the rat anterior pituitary gland with special reference to the intracisternal skeleton
Authors: Inoue Kinji , Kurosumi Kazumasa
Published: February 2005

A well‐developed plate‐like cisterna (PLC) associated with trans‐Golgi elements was observed in the Golgi apparatus of secretory cells in the rat anterior pituitary gland. This structure corresponds to the trans‐most sacculotubular network. The PLC maintains a remarkably uniform thickness of about 33 nm, as measured between the outer leaflets of its unit membrane structure. As to the mechanism by which this peculiar construction of the PLC is maintained, pillar‐like structures were noted in the PLC intracisternal space, apparently acting as supports to keep the intermembrane distance constant. The PLC was especially well developed in hypertrophied cells such as gonadotrophs following castration. One noteworthy feature was that the PLC frequently ran parallel with the rough endoplasmic reticulum (RER), maintaining a constant distance from the latter in hypertrophied cells, but no membrane continuity between the PLC and RER was seen.
Differential distribution and ultrastructural staining of oxytalan and elastic fibers in the periodontal ligament of Alligator mississippiensis
Authors: Takagi Minoru , Kazama Toshitada , Shimada Kazuyuki , Hosokawa Yasunobu , Hishikawa Hideki
Published: February 2005

We have investigated ultrastructural cytochemical properties of elastic elements in Alligator periodontal ligaments decalcified with EDTA and stained with 1) the tannic acid‐uranyl acetate (TA‐UA) method for elastin in combination with elastase digestion; 2) the high iron diamine‐thiocarbohydrazide‐silver proteinate (HID‐TCH‐SP) method with prior treatment of specimens with either monopersulphate or cupric‐sulphite reagent for the localization of disulphide‐ and/or sulphydryl‐containing material (i.e., oxytalan fibers); and 3) HID‐TCH‐SP alone for sulphated complex carbohydrates. Many microfibrils accumulated to form either large or small bundles. Large bundles having a diameter of 2.50 ± 1.10 μm (mean ± SD; n = 50) each showed an apico‐occlusal distribution, although small bundles measuring 0.63 ± 0.13 μm (mean ± SD; n = 50) in diameter each were exclusively localized in interstitial areas rich in vessels and nerves. The former bundles always lacked TA‐UA reactivity and represented oxytalan fibers; the latter bundles frequently contained TA‐UA‐reactive elastase digestable components and were similar in appearance to immature elastic fibers or elaunin fibers. HID‐TCH‐SP after oxidation strongly stained both the oxytalan and elastic fiber microfibrils but stained the amorphous elastin very weakly or not all. In nonoxidized specimens, there was no definite HID‐TCH‐SP staining of microfibrils and the amorphous elastin, although adjacent matrix proteoglycans stained consistently. These results indicate that although there is a marked difference in the distribution and size of oxytalan and elastic fibers in Alligator periodontal ligaments, their associated microfibrils lack stainable sulphate groups but are enriched with disulphide and/or sulphydryl groups, as has been described in mammals.
Effects of estradiol and progesterone on diabetes‐associated utero‐ovarian atrophy in C57BL/KsJ (db/db) mutant mice
Authors: Garris David R.
Published: February 2005

The modulating effects of estradiol (E: 1 μg/3.5 days) and progesterone (P: 2 mg/3.5 days) on the obesity and hyperinsulinemic and hyperglycemic components of the diabetes‐obesity syndrome in female C57BL/KsJ (db/db) mice, which includes cellular atrophy and adiposity in the reproductive tract, were examined and compared to corresponding control (+?) parameters. All control and diabetic mice received oil (vehicle control), E, or P treatments starting at 4 weeks of age. Body weight, serum insulin levels, blood glucose concentrations, and uteroovarian lipoprotein lipase activites were analyzed at 8 and 16 weeks of age and related to the ultrastructural changes in the steriod‐sensitive uterine epithelium during the treatment period. Neither E nor P had any effect on body weights in (+?) or (db/db) mice. The pronounced diabetes‐associated elevation in serum insulin levels was enhanced by E, and suppressed by P, in 16‐week‐old (db/db) mice as compared with controls. By 16 weeks of age, the E therapy normalized blood glucose levels in diabetic mice to control levels, whereas P was ineffective in modulating the hyperglycemia. The reduction in blood glucose levels in E‐treated diabetic mice correlated temporally with the return of normal intracellular structure including the disappearance of intracellular lipid vacuoles characteristic of uterine epithelium cells of (db/db) mice. The diabetes‐induced rise in utero‐ovarian lipoprotein lipase activity was normalized by P‐therapy. The reduction in uteroovarian lipoprotein lipase activity coincided temporally with the demonstrated intracellular reorganization in (db/db) reproductive tract tissues. These data indicate that E and P therapies are effective modulators of mutation‐induced structural, metabolic, and functional changes in the reproductive tract and peripheral tissues of genetically diabetic C57BL/KsJ (db/db) mice. The ability to restore affected tissue structure and function in this mutant mouse model to that of controls suggests that gonadal steroids may correct, delay, prevent, or suppress the diabetes‐associated tissue atrophy and adiposity which characterizes this strain.
Binding of the blood group‐reactive lectins to human adult kidney specimens
Authors: Laitinen Liisa , Juusela Harri , Virtanen Ismo
Published: February 2005

The binding of a panel of blood group‐reactive lectins to frozen sections of human kidney was studied with a special emphasis on reactivity with endothelia and basement membranes. The blood group A‐reactive lectins, all specific for α‐D‐N‐acetylgalactosamine (GalNAc), Helix aspersa (HAA), Helix pomatia (HPA), and Griffonia simplicifolia I‐A4 (GSA‐I‐A4) agglutinins bound to the endothelium in specimens with blood groups A and AB. In other samples, these lectins reacted predominantly with tubular basement membranes, as well as with certain tubules. Both Dolichos biflorus (DBA) and Vicia villosa agglutinins (VVA), reported to react with blood group A1 substance, failed to reveal endothelia in most specimens, but bound differently to tubules in all blood groups. The blood group B‐reactive lectins, specific for α‐D‐galactose (α‐Gal) or GalNAc, respectively, GSA‐I‐B4 and Sophora japonica agglutinin (SJA), bound to the endothelia in specimens from blood group B or AB and in other specimens bound only to certain tubules. Among the blood group O‐reactive lectins, specific for α‐L‐fucose (Fuc), Ulex europaeus I agglutinin (UEA‐I) conjugates, but not other lectins with a similar nominal specificity, bound strongly to endothelia in specimens with blood group O. The UEA‐I conjugates bound distinctly more faintly to endothelia in specimens of other blood groups. The present results indicate that lectins, binding to defined blood group determinants, react with endothelia in specimens of the respective blood group status. Furthermore, they suggest that basement membranes and some tubules in the human kidney show a distinct heterogeneity in their expression of saccharide residues, related to their blood group status.
Structural characteristics of staircase‐type retzius lines in human dental enamel analyzed by scanning electron microscopy
Authors: Risnes S.
Published: February 2005

Based on a scanning electron microscopic (SEM) analysis of adjoining, acid‐etched planes cut through human cervical enamel, the structural characteristics of staircase‐type Retzius lines have been clarified. Structural features associated with this type of Retzius lines–such as cleftlike defects, decreased dimension of prisms, increased interprism, club‐shaped appearance of prisms, oblique ridges, and triangular regions–have been incorporated into a unifying, three‐dimensional model. A continuous discontinuity defect, involving both prisms and interprism, is a prominent feature of this type of Retzius lines. Prisms and interprism facing the deep aspect of the cleftlike defect show an enlarged, flat surface that encroaches on the cervically situated prisms being rebuilt from the same cleft. The initial part of a prism taking off from the cleft is of distorted shape. As the prism reaches the level of the interprism cleft, it abruptly regains its normal size and shape. The relationship between this type of Retzius lines and the carious process is discussed, and it is suggested that the discontinuity defect may retard the carious lesion due to a protective effect of its supposed organic content. The developmental events creating staircase‐type Retzius lines are discussed, and it is suggested that Tomes' processes are constricted near their bases with a corresponding increase in interprismatic growth region. Tomes' processes will have to reshape plastically as they move out of the constricted pits, trailing the parent ameloblasts as they resume enamel production and move in the direction of the prisms.
Normal variations in the relationship of the tricuspid valve to the membranous septum in the human heart
Authors: Restivo Angelo , Smith Audrey , Wilkinson James L. , Anderson Robert H.
Published: February 2005

The anatomy of the antero‐septal commissure of the tricuspid valve and its relationship to the membranous part of the septum are described in 72 normal hearts from subjects ranging in age from 25 weeks gestation to 13 months. Three major patterns were found. According to whether the contiguous leaflets were fused at the commissure, joined at the circumference of the orifice, or left a gap at the commissural site, the varieties are described as undivided, annular, or gap commissure, respectively. Commissures of annular type showed further morphological varieties, as did the patterns of division of the membranous septum into its atrioventricular and interventricular components. Dominance of the atrioventricular component and/or absence of the interventricular membranous septum were encountered in 38 cases out of 72 (52%). This finding demonstrates that dominance of the atrioventricular membranous septum during fetal life and infancy is not universal. The variability noted in the morphology and position of the antero‐septal commissure was not associated with other positional variations of the tricuspid valve.
Calcification capacity of dental papilla mesenchymal cells transplanted in the isogenic mouse spleen
Authors: Ishizeki Kiyoto , Nawa Tokio , Sugawara Mitsutaka
Published: February 2005

The capacity of the dental pulp to form calcified tissue was examined in papilla cells dissociated from first molar tooth germs of the neonatal mouse and isografted in the spleen for up to 7 days. To obtain papilla cell populations without odontoblasts, pulpal mesenchyme was isolated mechanically from the enamel organ after 0.1% trypsin treatment and rolled on a membrane filter. On day 3 after transplantation, the grafted papilla cells had changed into large, spindle‐shaped cells, and initial calcification with needle‐like crystals began in association with the collageneous matrix surrounding those cells. On day 7 after transplantation, the spindle cells transformed into odontoblast‐like cells containing well‐developed secretory organelles, and irregular, but nontubular, calcified tissues were commonly observed surrounding the extracellular collagenous matrix. The calcified tissue matrix with cellular inclusions displayed a structure similar to that of osteodentin. During this period, an intense positive reaction for alkaline phosphatase (ALPase) activity was demonstrated along the cell membranes of the odontoblast‐like cells aligned at the periphery of forming calcified tissue. Enzymatic activity could not be detected on the cells incorporated completely into osteodentin‐like matrix. The present results show that the papilla cell population transplanted into the spleen formed osteodentin‐like material, thus demonstrating the capacity of papilla cells to produce calcified tissue.
Vascular network in papillae of dog oral mucosa using corrosive resin casts with scanning electron microscopy
Authors: Kishi Yoshiaki , Takahashi Kazuto , Trowbridge Henry
Published: February 2005

The purpose of this study was to undertake a three‐dimensional analysis of the vascular network of the lamina propria in the gingiva, alveolar mucosa, buccal mucosa, palate, and lingual mucosa of the dog. Using the corrosive resin casting technique, casts of the vascular network were prepared and examined by scanning electron microscopy.

In the oral mucosa, larger arteries in the submucosa divide into smaller branches that enter the lamina propria. These branches form one or more layers of vessels at the base of the papillae of the lamina propria, the so‐called subpapillary vascular network. Here the vessels divide again and enter the papillae to form a subepithelial capillary network. The configuration of the capillary loops within each papilla of the lamina propria is determined by the shape of the papilla. The characteristic shape of the loops resembles a hairpin. The capillary loops in the lingual papillae are larger and more complex than capillary loops found elsewhere in the oral mucosa. The mucosa of the posterior portion of the hard palate, the soft palate, and the tongue contain many venous valves.
Combined time‐lapse cinematography and immuno‐electron microscopy
Authors: Balfour B. M. , Goscicka T. , MacKenzie J. L. , Gautam A. , Tate M. , Clark J.
Published: February 2005

A method was developed to record interactions between mobile non‐adherent immunocytes by time‐lapse cinematography and then to study the same cells by immuno‐electron microscopy, using monoclonal antibodies against surface components. For this purpose a modified stage was designed to fit an inverted microscope. The attachment included a device to cool the culture chamber with N2 gas, a micro‐injector for monoclonal antibody and immuno‐gold treatment, and two pairs of washing needles to change the medium without disturbance. The technique was first employed to study the formation of aggregates around the antigen‐presenting cells in cultures containing cells from hyper‐immunized animals. Recently peripheral blood cells from normal subjects and patients with immune deficiency syndromes were stimulated with pokeweed mitogen, cluster formation was recorded, and the cells were processed for immuno‐electron microscopy.
Platelet membrane skeleton revealed by quick‐freeze deep‐etch
Authors: Bearer Elaine L.
Published: February 2005

Actin polymerization is an essential component of platelet activation. Since actin appears to polymerize at its membrane‐associated end, knowledge of the structural relationship of actin filaments to membrane is an important part of understanding that polymerization process. A membrane‐associated actincontaining cytoskeleton has been described in human platelets biochemically and is composed, at least in part, by an association between glycoprotein Ib and the actin‐binding protein originally isolated from macrophages. Many other actinassociated proteins with known sub‐membranous localization in other systems have been found in platelets, including alpha‐actinin, vinculin, and low levels of spectrin and the red cell protein Band 4.1. Because of the density of the platelet cytoplasm, the structure of the membrane‐skeleton has not yet been visualized. We have used quick freeze‐deep etch techniques to observe the sub‐membranous cytoplasm and report visualization of a periodic, submembranous filament system not before seen in the platelet. This filamentous system was more easily observed in thrombin‐stimulated platelets, but appeared to be present in resting, discoid cells as well. The filaments could also be readily observed when platelets are lysed after fixation, stained with tannic acid, and embedded for thin‐sectioning. This membrane cytoskeleton was composed of 9 nm thick filaments lying 15 nm apart, and 15 nm from the membrane. The filaments appeared to lie in parallel and to encircle the cell. Similar filaments could be seen associated with intracytoplasmic membrane systems in activated cells.
Renin immunohistochemistry in the adrenal gland of the mouse fetus and neonate
Authors: Kon Yashuhiro , Hashimoto Yoshiharu , Kitagawa Hiroshi , Sugimura Makoto , Murakami Kazuo
Published: February 2005

The development of renin‐containing cells in fetal and neonatal adrenal glands of the mouse was studied using immunohistochemistry. On days 13–14 of gestation, immunoreactivity for renin was first observed in a few cortical cells of the gland, appearing as small patchy or granular reaction products in the perikaryon. The mitotic configurations of the cells demonstrating immunoreactivity were noted. On day 16 of gestation, a number of intensively immunoreactive cells were distributed in the aortal side of the cortical zone. On day 18 of gestation, and day 1 postparturition, a small number of potent immunoreactive cells were still found in the cortical area. Immunoreactivity of the cytoplasm was observed in the cells, some showing an intensive reaction and other possessing numerous tiny granules just below the cell membrane. On days 3, 5, and 7 after birth, no renincontaining cells were found in the adrenal gland. The ratio of the numbers of renin‐positive cells in certain areas to the numbers in the entire cortical area was significantly increased on day 16 of gestation, but there was no sexual difference in the ratios. The ratios were decreased subsequently until day 1 after birth. The possible significance of renin synthesis in specific adrenal cells in fetal life is discussed with respect to an important involvement of angiotensin II in the morphogenesis of the adrenal gland of the mouse.
Cadmium toxicity to the cornea of pregnant rats: Electron microscopy and x‐ray microanalysis
Authors: Yoshizuka Mitsuaki , McCarthy Kevin J. , Kaye Gordon I. , Fujimoto Sunao
Published: February 2005

Cadmium toxicity to the cornea of pregnant rats was studied using the electron microscope and x‐ray microanalyzer. In in‐vivo experiments, severe corneal edema occurred in pregnant dams that received intraperitoneal injections of cadmium sulphate for 4 days during gestation, but not in nonpregnant rats. Prominent swelling of mitochondria and the occurrence of intra‐ and inter‐cellular vacuoles in the corneal endothelium were observed only in pregnant dams.

In in‐vitro experiments, electron‐dense deposits consiting of cadmium‐oxine complexes were preferentially found in swollen mitochondria of the endothelial cells. Cadmium peaks were obtained from these deposits with x‐ray microanalysis.

These data suggest that the corneal edema observed after administration of cadmium may imply the disturbance of pump function and barrier function of the corneal endothelium due to the primary toxic effects of this metal on mitochondria.
Migration of fetal intestinal intervillous cells in neonatal mice
Authors: Calvert Raymond , Pothier Pierre
Published: February 2005

The migration of intestinal intervillous epithelial cells labeled in the fetus was followed in neonatal mice. At 17 days of gestation, a first group pregnant mice received three intraperitoneal injections of 3H‐thymidine (150 μCi/injection) administered at 30 min intervals. Two mothers were sacrificed 3 hours after the first injection. Mice from different litters were also sacrificed on days 0, 2, 4, 8, 12, 14, and 16 after birth. A second group of pregnant mice was injected at 18½ days of gestation and offspring were sacrificed on days 6, 8, 10, 12, 14, and 16 after birth. Segments of duodenum and ileum were fixed in glutaraldehyde, postfixed in osmium tetroxide, dehydrated, and embedded in Epon. Sections were stained with aldehyde fuchsin and processed for radioautography. By following the leading front and trailing edge of labeled cells in the longest villi of the duodenum and ileum, we observed that 1) extrusion zones become active immediately after birth and 2) the longest villi do not elongate until 10 days after birth in the duodenum and 14 days in the ileum, that is, when all labeled epithelial cells originally present in the fetus have been extruded. Moreover, by measuring the distance between the internal limit of the inner circular layer of smooth muscle and the intervillous epithelium at 17 days of gestation (12.95 ± 1.18 μm) or the bottom of the crypts at day 3 (14.81 ± 0.91μm), we propose that crypts do not develop as downgrowth: rather the intervillous epithelium is reshaped and the crypt‐villus junction moves upward, away from the muscularis externa.

In conclusion, by analyzing the growth pattern of the longest villi in neonatal mice, we have found that a steady state between cell production and cell extrusion is reached at birth in the duodenum and by day 4 in the ileum. This steady state will be lost however, after day 10, thus enabling lengthening of the villi.
Cells resembling intraventricular macrophages are present in the subretinal space of human foetal eyes
Authors: McMenamin Paul G. , Loeffler Karin U.
Published: February 2005

The subretinal spaces (SRS) in 17 human foetal eyes were investigated by light microscopy and scanning and transmission electron microscopy. A hitherto undocumented group of pleomorphic cells was detected on the apical surface of the retinal pigment epithelium (RPE) and on the undersurface of the neural retina. These cells formed a regularly spaced array in the peripheral SRS, particularly in the most anterior portion nearest the ciliary body anlage. The morphology of the SRS cells ranged from a small round or ovoid from with a few short basal pseudopodia to an extremely flattened dendritic form. Ultrastructural features, such as large melanophagolysosomes, consistent with a phagocytic function, were observed in some cells. These SRS cells bore remarkable resemblance to epiplexus and supraependymal cells, considered to be the resident population of macrophages on the ventricular surfaces of the brain. This morphological parallelism, together with the anatomically homologous location, is strong evidence that SRS cells represent a normal population of macrophages in the developing human eye. No features consitent with an RPE or neuronal origin were observed. The possible role of these cells as transient phagocytes in the SRS with a possible destiny as retinal microglia is discussed.
Morphogenesis of the frontal organ in Bufo bufo during development
Authors: Farnesi R. M. , Tei S. , Vagnetti D. , Di Rosa I. , Fagotti A. , Santarella B.
Published: February 2005

Morphogenesis of the frontal organ in Bufo bufo was examined under transmission electron microscope. Many remarkable similarities to the frontal organ of other Amphibia Anura are observed. It originates from a diverticulum in the dorsal region of the neural tube. It is egg‐shaped, has an eccentric lumen, and is made up of three kinds of cells: 1) photoreceptors, which protrude into the lumen; 2) supportive cells; and 3) ganglion cells, which make synaptic contact with the photoreceptors. Peculiar to Bufo bufo is the melanin‐like pigments around the light‐sensitive part of the photoreceptors. These pigments may prevent light dispersion. The frontal organ in Bufo bufo starts degenerating during the early premetamorphic stages.
An immunohistochemical approach to the intrafusal fibers of extraocular muscle spindles in sheep, cow, and pig
Authors: Scapolo P. A. , Costerbosa G. Lalatta , Barazzoni A. M. , Lucchi M. L. , Bortolami R.
Published: February 2005

Intrafusal muscle fibers of the extraocular muscles (EOMs) of the sheep, cow, and pig were studied histochemically and immunohistochemically. In sheep and cow spindles, three intrafusal fiber types, namely the bag1, bag2, and chain fibers, were identified by a combination of standard histochemical methods and immunohistochemical staining with antibodies selective for slow‐tonic (antitonic ALD) and slow twitch (anti‐I BA‐D5) myosin. The bag1 and bag2 fibers appeared immunologically different on the basis of their differential reactivity with the two antisera. Anti‐tonic ALD preferentially stained the bag1 fibers, whereas anti‐I BA‐D5 labeled the bag2 fibers. Chain fibers did not react with either antisera. In the pig EOM spindles, in general, one bag and some chain intrafusal fibers were identified. The bag fiber was labeled by anti‐tonic ALD, but it did not react with the anti‐I BA‐D5. These findings point to the existence in pig EOM spindles of only one bag fiber antigenically similar to the bag1 fiber of the other species examined.
Ultrasound investigation of fetal human upper respiratory anatomy
Authors: Wolfson Victoria P. , Laitman Jeffrey T.
Published: February 2005

Although the human upper respiratory—upper digestive tract is an area of vital importance, relatively little is known about either the structural or functional changes that occur in the region during the fetal period. While investigations in our laboratory have begun to chart these changes through the use of postmortem materials, in vivo studies have been rarely attempted. This study combines ultrasonography with new applications of video editing to examine aspects of prenatal upper respiratory development.

Structures of the fetal upper respiratory—digestive tract and their movements were studied through the use of ultrasonography, and detailed frame‐by‐frame analysis. Twenty‐five living fetuses, aged 18–36 weeks gestation, were studied in utero during routine diagnostic ultrasound examination. These real‐time linear array sonograms were videotaped during each study. Videotapes were next analyzed for anatomical structures and movement patterns, played back through the ultrasound machine in normal speed, and then examined with a frame‐by‐frame video editor (FFVE) to identify structures and movements. Still images were photographed directly from the video monitor using a 35 mm camera.

Results show that upper respiratory and digestive structures, as well as their movements, could be seen clearly during normal speed and repeat fram‐by‐frame analysis. Major structures that could be identified in the majority of subjects included trachea in 20 of 25 fetuses (80%); larynx, 76%; pharynx, 76%. Smaller structures were more variable, but were nevertheless observed on both sagittal and coronal section: piriform sinuses, 76%; thyroid cartilage, 36%; cricoid cartilage, 32%; and epiglottis, 16%. Movements of structures could also be seen and were those typically observed in connection with swallowing: fluttering tongue movements, changes in pharyngeal shape, and passage of a bolus via the piriform sinuses to esophagus. Fetal swallows had minimal laryngeal motion. This study represents the first time that the appearance of upper airway and digestive tract structures have been quantified in conjunction with their movemements in the living fetus.
Electron microscopic evaluation of the occurrence of matrix vesicles in cartilage
Authors: Mitchell Nelson S. , Shepard Nora L.
Published: February 2005

Troubled by variations in the descriptions of shape, appearance, and content of matrix vesicles and the conflicting reports of increased numbers of vesicles in the mineralizing regions of the growth plate contrasted with larger numbers in the resting zone, we embarked on a review of matrix vesicles in the growth plate using a comparison of different fixation techniques. We found matrix vesicles resembling cell debris at all levels of the growth plate, with no particular association with mineral. Lipid bodies surrounded by a membrane of proteoglycan have also been seen in large numbers. The cell debris–like matrix vesicles have been the common finding in reports of digested centrifuged cartilage and may represent cytoplasmic processes. Lipid bodies surrounded by proteoglycan may be similar to the membrane‐bound vesicle described by Ali (Fed. Proc., 35:135–142, 1987) and by Bonucci (Clin. Orthod., 78:108–133, 1971).