bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphocyte subpopulations in high endothelial venules and lymphatic capillaries of bronchus‐associated lymphoid tissue (BALT) in the rat
Authors: Otsuki Yoshinori , Ito Yuko , Magari Sumiko
Published: February 2005

The subpopulations of lymphocytes and non‐lymphoid cells in high endothelial venules (HEV) and in lymphatic capillaries surrounding lymphoid follicles in bronchus‐associated lymphoid tissue (BALT) were examined by electron microscopy after preembedding the tissue and staining with an immunoperoxidase technique. The results were compared with those obtained in gut‐associated lymphoid tissue (GALT) reported previously. Monoclonal mouse‐anti‐rat T cell, IgG, IgM, IgA, and Ia antisera were used. Plasma cells that were reactive to anti‐IgG, anti‐IgM, and anti‐IgA were detected as cells in which the 3′, 3′ ‐diaminobenzidine tetrahydroxychloride reaction product was localized in rough endoplasmic reticulum and perinuclear spaces but not on plasma membranes. These plasma cells did not occur in either lymphatic capillaries or HEV in BALT as they did in GALT. Cells with surface Ig (sIg cells), T‐cell antigen (T cells), and Ia antigen (Ia cells) were present in BALT. T cells were located predominantly in the follicular area opposite the bronchial epithelium; IgM‐ and IgG‐reactive cells were found in the follicular area adjacent to the bronchial epithelium; and IgA‐positive cells were found in the lateral part of the area where the T cells were localized (T‐cell area). Ia cells were abundant throughout BALT and in moderate numbers in the epithelium. A striking observation was the presence of “nurse‐cell”‐like structures in the periphery of BALT. The percentages of T, sIgG, sIgM, and sIgA cells in the HEV were 54.7%, 2.4%, 28.9%, and 27.3%, respectively, and in the lymphatic capillaries, 41.2%, 3.8%, 38.2%, and 21.2%, respectively. Non‐lymphoid cells with Ia antigen, presumably interdigitating cells (IDC), were often seen in the two types of vessels. The percentage was 4. 3% in the HEV and 5.6% in the lymphatic capillaries. The results indicate that the largest common lymphocyte subpopulation in the two types of vessels surrounding follicles in BALT is T cells, followed by sIgM or sIgA cells as seen in GALT; IDC may be one of the main migrating cells within BALT.
Morphogenesis of endoplasmic reticulum in Xenopus oocytes after microinjection of rat liver smooth microsomes
Authors: Paiement Jacques , Dominguez J. M. , McLeese J. , Bernier J. , Roy L. , Bergeron M.
Published: February 2005

We have determined the kinetics of endoplasmic reticulum (ER) reconstitution following insertion of rat‐liver smooth microsomes (SM) into Xenopus oocyte cytoplasm using electron microscopy as well as cytochemistry and thick‐section 3‐dimensional reconstruction. Oocytes were fixed 0, 10, 20, 40, 80, and 120 min after microinjection with SM and processed for thin‐ and thick‐section electron microscopy. At 0 min postinjection, rat liver SM were observed as small vesicles and were loosely dispersed amongst oocyte organelles. At 10 min, tubules were discerned among many elongate vesicles; and these structures comprised large cytoplasmic regions delimited by mitochondria and yolk platelets. By 20 min, segregation of transplanted organelles yielded yolk‐platelet‐free regions composed of few vesicles but increasingly numerous, long and anastomosing tubules. By 40 min, a network with numerous tubular branches and fenestrations was observed among the few remaining vesicles. By 80 min, transformation of rat liver SM into a complex network of branching and anastomosing tubules was complete. Three‐dimensional reconstruction revealed the network to be composed of interconnecting elements consisting of anastomosing tubules. The reconstituted network of anastomosing tubules in Xenopus oocytes was compared to the network of anastomosing tubules in rat liver hepatocytes and was found to be essentially identical. Network formation occurred in oocytes pretreated with either vinblastine (40 μM) or nocodazole (0.166 μM), and network organization was maintained in oocytes treated with the same drugs after microinjection and reconstitution. We conclude that SM retain sufficient molecular information for rapid self‐assembly into structures resembling those in the cells from which they were derived. Both the assembly and maintenance of ER structure in oocyte cytoplasm are microtubule‐independent. The formation of such structures following microinjection of SM into living cells provides a unique assay for this type of membrane subfraction.
Ultrastructural and cytoarchitectural features of lymphoreticular organs in the colon and rectum of adult BALB/c mice
Authors: Owen Robert L. , Piazza Anthony J. , Ermak Thomas H.
Published: February 2005

The structure and function of colonic mucosal lymphoid organs remain largely unexplored, especially in the rectum hidden within the pelvic vault. Two‐month‐old female BALB/c mice were anesthetized, and the entire colon was removed from cecum to anus. Distal colonic patches were then prepared for electron microscopy or were quick‐frozen and sectioned for immunoperoxidase localization of B cells and T cell subsets. Aggregated lymphoid follicles were distributed irregularly along the entire colon with an average of 1.4 patches per centimeter of colon length. There were large collections of follicles opposite the ileocecal valve (cecal patches), variable numbers of patches throughout the colon, and at least one patch within 10 mm of the anus (rectal patch). Follicles were adjacent to branching crypts lined by epithelium infiltrated by lymphoid cells and containing few goblet cells. In electron micrographs, M cells were identified by their short, irregular microvilli; intraepithelial lymphoid cells; reduced lysosomal dense bodies; and an expanded tubulovesicular network. Small germinal centers were seen. Cytoarchitectural components of colonic lymphoid follicles and Peyer's patch follicles were remarkably similar, despite differences in surrounding mucosa and luminal microbial exposure. The presence of organized lymphoid tissue with M cells and germinal centers suggests that transepithelial particle transport and antigen recognition can take place in the rectum. Whether such tissue has the capacity for uptake of luminal microorganisms is of particular interest, not only because colonic follicles may be sites for local initiation of immune responses but also because they may be important entry points for systemic infection.
Subcellular distribution of [3H]‐dexamethasone mesylate binding sites in leydig cells using electron microscope radioautography
Authors: Stalker Alison , Hermo Louis , Antakly Tony
Published: February 2005

The present view is that glucocorticoid hormones bind to their cytoplasmic receptors before reaching their nuclear target sites, which include specific DNA sequences. Although it is believed that cytoplasmic sequestration of steroid receptors and other transcription factors (such as NFKB) may regulate the overall activity of these factors, there is little information on the exact subcellular sites of steroid receptors or even of any other transcription factors. Tritiated (3H)‐dexamethasone 21‐mesylate (DM) is an affinity label that binds covalently to the glucocorticoid receptor (GR), thereby allowing morphological localization of the receptor at the light and electron microscope levels as well as for quantitative radioautographic (RAG) analysis. After injection of 3H‐DM into the testis, a specific radioautographic signal was observed in Leydig cells, which correlated with a high level of immunocytochemically demonstrable GR in these cells at the light‐microscope level. To localize the 3H‐DM binding sites at the electron microscope (EM) level, the testes of 5 experimental and 3 control adrenalectomized rats were injected directly with 20 μCi 3H‐DM; control rats received simultaneously a 25‐fold excess of unlabeled dexamethasone; 15 min later, rats were fixed with glutaraldehyde and the tissue was processed for EM RAG analysis combined with quantitative morphometry. The radioautographs showed that the cytosol, nucleus, smooth endoplasmic reticulum (sER), and mitochondria were labeled. Since the cytosol was always adjacent to tubules of the sER, the term sER‐rich cytosol was used to represent label over sER networks, which may also represent cytosol labeling due to the limited resolution of the radioautographic technique. Labeling was highest in sER‐rich cytosol and mitochondria, at 53% and 31% of the total, respectively. Cytosol (exclusively of all organelles) and nucleus showed comparatively weak labeling, at 9% and 7%, respectively. This study thus clearly establishes with the electron microscope, the localization of glucocorticoid binding sites using DM. It remains to be determined whether or not these DM binding sites represent bona fide glucocorticoid receptors or nonreceptor proteins that bind DM. Whereas the functional significance of the subcellular distribution of DM is not known, the labeling of the cytosol may represent localization of the steroid and GR in their traditional compartment. The steroid antagonistic properties of DM may have prevented the DM‐GR complexes from translocating to the nucleus. However, the significant labeling of the sER‐rich cytosol and mitochondria was unexpected and raises intriguing questions that are being addressed in current studies.
Calcitonin gene‐related peptide‐immunoreactive nerves in the rat kidney
Authors: Knight D. S. , Cicero S. , Beal J. A.
Published: February 2005

Cryostat‐ and vibratome‐cut rat kidney secretions were singly or doubly labeled to visualize immunoreactive calcitonin‐gene‐related peptide (CGRPI) and substance P (SPI). Rats were perfused with 2–4% paraformaldehyde + 0.15% picric acid then rinsed with buffer. Horseradish peroxidase (HRP) was used to visualize CGRP in vibratome sections, and combined HRP and fluorophore were used to visualize the two peptides simultaneously in cryostat sections. There is a complex, multilayered plexus of CGRP nerves on the renal pelvis and a less dense, single‐layered plexus on the major branches of the renal artery and on interlobar arteries and veins. A few axons innervate finer branches of the arterial tree and other intrarenal structures. Results of double immunolabeling suggest that SPI axons comprise a subpopulation of the CGRP axon population in the rat kidney. There was no evidence for a separate population of SPI axons.
Parent‐specific expression of a human keratin 18/β‐galactosidase fusion gene in transgenic mice
Authors: Thorey Irmgard S. , Pedersen Roger A. , Linney Elwood , Oshima Robert G.
Published: February 2005

Insertion of a human keratin 18 (K18)‐bacterial β‐galactosidase (LacZ) fusion gene into mice has led to a unique transgenic line in which expression of the transgene is subject to unusual germ line‐specific, genomic imprinting effects. Fetal expression of the LacZ reporter gene depends on the gender of the transmitting parent, with appropriate expression in liver after maternal inheritance, and ectopic expression in retina and mesodermal tissues after paternal inheritance. This tissue‐specific imprinting pattern is superimposed upon a basic expression pattern which is unaffected by parental inheritance. Insertion of the transgene has led to a recessive‐lethal phenotype, with no parent‐of‐origin effects on viability, suggesting that the transgene has not inserted into an imprinted region of the genome. HpaII and HhaI methylation sensitive restriction sites within the bacterial LacZ reporter gene are completely methylated when activity of the maternally inherited transgene is detected in the fetal liver, and not methylated when the paternally inherited transgene is silent. Thus DNA methylation of LacZ is correlated with maternal inheritance and may be implicated in the genomic imprinting mechanism as others have suggested. However, in contrast to the commonly found correlation of expression and low DNA methylation, the LacZ gene was expressed in fetal liver when fully methylated. This result may imply the existence of negative regulatory activities that recognize the unmethylated LacZ gene. © 1992 Wiley‐Liss, Inc.
Connexin expression and gap junction communication compartments in the developing mouse limb
Authors: Laird Dale W. , Yancey S. Barbara , Bugga Lakshmi , Revel Jean‐Paul
Published: February 2005

Fundamental to the understanding of mouse limb morphogenesis and pattern formation is the need to elucidate the spatial and temporal distribution of gap junction proteins (connexins, Cx) and cell‐cell communication compartments. To this end, we used immunofluorescence and confocal microscopy together with 3‐dimensional reconstruction software to map the distribution of Cx43 and Cx32 in 11–14.5 days postcoitum (dpc) mouse limbs. Cx43 was strictly localized to the apical ectodermal ridge (AER) and non‐ridge ectoderm throughout all stages of mouse limb development studied. Cx32, on the other hand, was abundant in the mesenchyme with only low levels of expression in the 11–13.5 dpc ectoderm. However, at 14–14.5 dpc there was a clear increase in Cx32 expression in the ectoderm. Double labeling for connexins and confocal microscopy revealed Cx43 and Cx32 in the same optical section of the basal cells of the ectoderm but in separate plaques. Lucifer yellow dye injections showed that the cells of the AER were in direct communication with the nonridge ectoderm but dye was never observed to spread to the mesenchyme. Cells of the mesenchyme were coupled to each other but to a much lesser extent than cells of the ectoderm. Finally, although there was an increase in Cx32 expression in the ectoderm at 14–14.5 dpc, this was not correlated with any detectable change in communication compartments. Thus, the lack of dye transfer between the ectoderm and underlying mesenchyme from the peak of AER height through its decline suggests that bulk transfer of morphogens between these two layers is not necessary for mouse limb development. © 1993 Wiley‐Liss, Inc.
Xenopus gastrulation without a blastocoel roof
Authors: Keller Ray , Jansa Sharon
Published: February 2005

The objective of this paper is to determine the function in gastrulation of several of the five major regional morphogenetic processes in the African clawed frog, Xenopus laevis. These regional processes are (1) epiboly of the animal cap (AC); (2) migration of the mesoderm on the roof of the blastocoel; (3) convergence and extension of the dorsal, noninvoluting marginal zone (NIMZ); (4) formation of the bottle cells at the site of blastopore formation; and (5) convergence and extension of the involuting marginal zone (IMZ). After the AC and the NIMZ were removed, thus eliminating the first three of these processes, the IMZ involuted, constricted, and closed the blastopore. It also converged and extended to form notochord and somites, although these tissues were often crooked and sank into or were covered over by the vegetal endoderm. When the AC was removed, the dorsal axial mesoderm involuted and stuck to the inner surface of the NIMZ. The IMZ and NIMZ converged and extended together to form a longer, straighter axis than that formed by the IMZ alone. Moreover, presence of the NIMZ also prevented the sinking of the IMZ into the endoderm. Misalignment of the available AC‐NIMZ substratum and the IMZ at the beginning of gastrulation suggested that the IMZ determines the general direction of its own extension. Absence of the AC‐NIMZ accelerated and increased the normal effects of bottle cell formation on the IMZ and vegetal endoderm. In absence of the AC‐NIMZ as a substratum on which to migrate, prechordal mesoderm was pushed anteriorly by the converging and extending mesoderm behind it, but it did not spread normally. We conclude that (1) involution and blastopore closure by the IMZ can occur without pushing by epiboly and convergence and extension of the NIMZ‐AC; (2) involution and blastopore closure can occur without migration of the mesoderm on the blastocoel roof; (3) convergence and extension of the IMZ are sufficient to bring about IMZ involution and blastopore closure; (4) the function of bottle cells in initiating involution is retarded by presence of the NIMZ‐AC; (5) the associated dorsal NIMZ and IMZ together form an axis that extends better and is perhaps stiffer than the IMZ alone; and (6) the dorsal axial and paraxial mesoderm form the “skeleton” around which the mechanics of the other parts of the embryo are organized. These findings are important for the analysis of gastrulation by cellular, genetic, and molecular approaches. © 1993 Wiley‐Liss, Inc.
Neurofibromin, a predominantly neuronal GTPase activating protein in the adult, is ubiquitously expressed during development
Authors: Daston Maryellen Maneri , Ratner Nancy
Published: February 2005

The onset of manifestations of the common, autosomal dominantly inherited disease type 1 neurofibromatosis (NF1) is usually in childhood. To begin to understand the pathogenesis of NF1, we analyzed the developmental pattern of expression of the protein product of the NF1 gene, neurofibromin, by Western blotting and immunohistochemistry using the rat as a model system. Neurofibromin is uniformly distributed throughout embyronic day 10 and 12 rat embryos. By embryonic day 16, neurofibromin immunore‐activity is enriched in neurons of the cortical plate, in peripheral ganglia, and in developing CNS and PNS fiber tracts, but remains detectable outside the nervous system. Expression decreases in nonneural tissues by postnatal day 6, and neurofibromin is greatly decreased (lung, adrenal cortex, skin) or absent (skeletal muscle, cartilage) in adult tissues except for brain, spinal cord, peripheral nerve, and adrenal medulla. Transient expression of neurofibromin during development in many tissues suggests the importance of this GTPase‐activating protein in morphogenesis and organ growth. A separate role is proposed for neurofibromin in growing axons and in the mature nervous system. © 1993 Wiley‐Liss, Inc.
Tissue‐specific expression of type XII collagen during mouse embryonic development
Authors: Oh Suk Paul , May Griffith C. , Hay Elizabeth D. , Olsen Bjorn R.
Published: February 2005

Polyclonal antibodies were raised in rabbits against a fusion peptide representing a portion of the amino‐terminal non‐triplehelical domain of mouse type XII collagen. The antibodies reacted with bands of 220 and 350 kDa on Western blots of mouse tissue extracts. Immunohistochemical analyses of mouse embryos demonstrated that type XII collagen is expressed mainly in dense connective tissues of tendons, ligaments, dermis, cornea, blood vessel walls, meninges, and developing membranous bones. Comparison of skin extracts and medium of cultured mouse skin fibroblasts by Western blotting showed that while tissues contain short 220 kDa type XII collagen polypeptides as well as the long form, cultured cells produce mainly the long form with 350 kDa polypeptides. © 1993 wiley‐Liss, Inc.
Early heart development: Dynamics of endocardial cell sorting suggests a common origin with cardiomyocytes
Authors: Linask Kersti K. , Lash James W.
Published: February 2005

The myocardial and endocardial cell sorting out processes take place primarily between 19 and 29 hr of development in the avian embryo. This occurs in an apparent rostral to caudal wave through the heart forming region. During heart development considerable uncertainty exists regarding the processes that regulate cell commitments, progressive aggregation, and sorting out of the different precardiac cell populations. The question addressed in this report is whether endocardial and myocardial cells have a common origin or do the endocardial cells arise from a distinct population of cells from within the precardiac mesoderm. These cells then migrate to become localized between the developing myocardium above and the endoderm below. The distribution of preendocardial cells and premyocardial cells has been followed immunohistochemically in quail heart‐forming region mesoderm explants from embryos approximately 18 hr in development and incubated for a 24‐hr period. Differentiating myocardiocytes were immunostained with anti‐N‐cadherin and endocardiocytes with QH‐1, a monoclonal antibody that recognizes an antigenic determinant on quail endothelial cells. Sparsely localized QH‐1 labeled endothelial cells are localized in the stage 5 heart‐forming region. These cells are often arranged in a columnar fashion in the mesoderm explants 6 hr after explantation. By 15–22 hr large patches of QH‐1 expressing cells are interspersed with the N‐cadherin expressing myocardiocytes. A subpopulation of cells express both N‐cadherin and QH‐1 antigen suggesting that endocardial and myocardial cells may arise from a common precursor population and that N‐cadherin regulation may be a mechanism underlying specific cell sorting of these two cell populations during heart development. © 1993 wiley‐Liss, Inc.
Perlecan gene expression precedes laminin gene expression during differentiation of F9 embryonal carcinoma cells
Authors: Chakravarti Shukti , Hassell John R. , Phillips Stephen L.
Published: February 2005

F9 embryonal cells can be induced to differentiate and synthesize basement membrane proteins. Perlecan and laminin are two basement membrane constituents that have extensive regions of homology. Expression of perlecan and laminin B1 genes was followed during differentiation of F9 cells by measurements of transcription rate and mRNA abundance using nuclear run on assays and Northern hybridizations, respectively. The rate of precursor protein synthesis was determined by immunoprecipitation from lysates of pulse‐labeled F9 cells. The results showed that perlecan gene expression responds more rapidly after induction than does laminin B1 gene expression but is ultimately expressed at a substantially lower level than laminin. Thus, the perlecan and laminin genes appear to be regulated by different mechanisms and their gene products are not made in stoichiometric amounts. © 1993 Wiley‐Liss, Inc.
Expression of homeobox genes Msx‐1 (Hox‐7) and Msx‐2 (Hox‐8) during cardiac development in the chick
Authors: Chan‐Thomas Penny S. , Thompson Robert P. , Robert Benoît , Yacoub Magdi H. , Barton Paul J. R.
Published: February 2005

The vertebrate homeobox genes Msx‐1 and Msx‐2 are related to the Drosophila mshgene and are expressed in a variety of tissues during embryogenesis. We have examined their expression by in situ hybridisation during critical stages of cardiac development in the chick from stages 15 + to 37. Msx‐1 expression is apparent in a number of non‐myocardial cell populations, including cells undergoing an epithelial to mesenchymal transformation in the atrioventricular and the outflow tract regions that play an integral role in heart septation and valve formation. Msx.2 expression is restricted to a distinct subpopulation of myocardial cells that, in later stages, coincides morphologically with the cardiac conduction system. The timing of Msx‐2 expression suggests that it plays a role in conduction system tissue formation and that it identifies precursor cells of this specialised myocardium. The pattern of Msx‐2 expression is discussed with reference to current models of conduction tissue development. © 1993 Wiley‐Liss, Inc.
Structural abnormalities associated with congenital megacolon in transgenic mice that overexpress the Hoxa‐4 gene
Authors: Tennyson Virginia M. , Gershon Michael D. , Sherman Diane L. , Behringer Richard R. , Raz Regina , Crotty David A. , Wolgemuth Debra J.
Published: February 2005

Congenital megacolon develops in transgenic mice that overexpress the homeobox‐containing gene, Hoxa‐4. The current study was done to identify abnormlities of the terminal colon that might account for the phenotype. The terminal bowel of transgenic mice was compared with that of control and lethal spotted (ls/ls) mice, a strain in which megacolon also develops. The terminal colon of the transgenic mice contained fewer ganglia than that of controls, but was hypoganglionic, rather than aganglionic like that of ls/ls mice. The neurons present in the adult transgenic colon were sifnificantly increased in size and a subset of very large neurons(>40 μm in maximum diameter) were observed. Electron microscopic studies of young adult transgenic mice revealed that the ganglia and nerves of the myenteric plexus had the ultrastructure of extraenteric peripheral nerve rather than that of the enteric nervous system (ENS). The myenteric ganglia in the transgenic animals contained Schwann cells associated with a basal lamina that enveloped axons completely and individually, instead of glia. Although collagen is excluded from the ganglia and thin nerve fibers of the normal ENS, a collagen‐containing endoneurium surrounded each of the axon‐Schwann cell units of the abnormal nerve fibers of the transgenic mice were located in these nerve bundles rather than in ganglia. There were smooth muscle abnormalities in the terminal bowel of the transgenic mice. Wide gaps were present in the longitudinal muscle of the transgenic mice; these gaps contained ganglia that were in contact with the adventitia. These longitudinal smooth muscle cells were more irregular than those of controls and they contained fewer puncta adherens; moreover, a larger proportion of the volume of the cytoplasm of transgenic smooth muscle cells was occupied by organelles. Finally, an extensive thickening and reduplication of the basal lamina surrounding the smooth muscle cells of the muscularis mucosa was observed in the transgenic colon and resembled that found in ls/ls mice. These data suggest that both smooth muscle and the innervation of the terminal bowel of neonatal Hoxa‐4 transgenic mice are structurally abnormal. Although some of the abnormalities seen in Hoxa‐4 transgenic mice are similar to those which arise in ls/ls mice, the two conditions are not identical. In both animals, the data are consistent with the hypothesis that the defects arise as a result of a defective interaction between the precursors of enteric neurons and smooth muscle. © 1993 Wiley‐Liss, Inc.
Tenascin is associated with articular cartilage development
Authors: Pacifici Maurizio , Iwamoto Masahiro , Golden Eleanor B. , Leatherman Judith L. , Lee Yun‐Shain , Chuong Cheng‐Ming
Published: February 2005

The roles of tenascin in cartilage development and function remain unclear. Based on the observation that tenascin is particularly abundant at the epiphyseal extremities of developing cartilaginous models of long bones in chick and mouse embryo, we tested the hypothesis that tenascin is involved in articular cartilage development. Immunofluorescence analysis revealed that tenascin was first localized in the cell condensation region of Day 4 chick embryo limb buds, where the cartilaginous models form. With further development, tenascin gene expression became indeed restricted to the articular cap of the models. Tenascin persisted in the articular cartilage of postnatal chickens but appeared to decrease with age. The protein was also abundant in embryonic and adult tracheal cartilage rings which, like articular cartilage, persist throughout postnatal life. Similar patterns of tenascin expression were seen in mouse. Using monoclonal antibodies to avian tenascin variants, we found that the bulk of articular cartilage contained the shortest tenascin variant (Tn190), whereas the largest variant (Tn230) was present in tissues associated or interacting with articular cartilage (ligaments and meniscus). The protein and its mRNA, however, were undetectable in growth plate cartilage undergoing maturation and endochondral ossification. This inverse correlation between chondrocyte maturation and tenascin production was corroborated by the finding that tenascin gene expression decreased markedly during maturation of a secondary ossification center within the articular cap in vivo. Thus, tenascin is intimately associated with the development of articular cartilage and other permanent cartilages whereas absence or reduced amounts of this matrix protein characterize transisent cartilages which undergo maturation and are replaced by bone. © 1993 Wiley‐Liss, Inc.
Expression patterns of the murine LIM class homeobox gene lim1 in the developing brain and excretory system
Authors: Fujii Tetsuya , Pichel Jose G. , Taira Masanori , Toyama Reiko , Dawid Igor B. , Westphal Heiner
Published: February 2005

We report the cloning, sequence analysis, and developmental expression pattern of lim1, a member of the LIM class homeobox gene family in the mouse. lim1 cDNA encodes a predicted 406 amino acid protein that is 93% identical with the product of the Xenopus LIM class homeobox gene Xlim1. We have characterized lim1 expression from day 8.5 post coitum onward. Northern blot analysis of RNA transcripts indicates that lim1 is expressed both during embryogenesis and in the adult brain. Analysis by whole‐mount and section in situ hybridization shows lim1 expression in the central nervous system from the telencephalon through the spinal cord and in the developing excretory system including pronephric region, mesonephros, nephric duct, and metanephros. In the metanephros, lim1 is strongly expressed in renal vesicles and S‐shaped bodies, and transcripts are also detected in the ureteric branches. © 1994 Wiley‐Liss, Inc.
Alternative splice form of type II procollagen mRNA (IIA) is predominant in skeletal precursors and non‐cartilaginous tissues during early mouse development
Authors: Sandell Linda J. , Nalin Andrew M. , Reife Robert A.
Published: February 2005

Type II collagen, generally considered to be characteristic of cartilage, has been localized in specific non‐cartilaginous structures during embryogenesis and development of the skeleton. Type II procollagen is synthesized in two different forms generated by alternative splicing of exon 2 in the precursor mRNA transcript. One form (type IIA procollagen) contains a large cysteine‐rich domain in the NH2‐terminal propeptide, while the second form (type IIB procollagen) does not. These two forms are spatially expressed during development and chondrogenesis with the type IIB procollagen mRNA primarily expressed by chondrocytes while the IIA form is expressed in chondroprogenitor cells (Sandell et al. [1991] J. Cell Biol. 114:1307–1319). The present study demonstrates that the early non‐cartilage expression, by somites, mesenchymal and epithelial cells, is predominately the alternate splice form, type IIA procollagen mRNA. Later in development, the type IIB mRNA splice form is expressed by chondrocytes. During the development of intramembranous bones, such as the mandible, type IIA procollagen mRNA is also expressed. In this tissue, the splice form does not switch to type IIB mRNA and no cartilage is formed. These results show that expression of type IIA mRNA, whether by epithelial or mesenchymal cells, precedes formation of overt skeletal structures. © 1994 Wiley‐Liss, Inc.
Expression patterns of mRNAs for the gap junction proteins connexin43 and connexin42 suggest their involvement in chick limb morphogenesis and specification of the arterial vasculature
Authors: Dealy Caroline N. , Beyer Eric C. , Kosher Robert A.
Published: February 2005

Gap junctions which comprise a family of proteins called connexins have been implicated in the morphogenesis of the chick limb bud. We have examined the expression patterns of two members of the connexin family, connexin43 (Cx43) and connexin42 (Cx42), during the early development of the chick limb bud and embryo by in situ hybridization. Cx43 mRNA is expressed in high amounts in the apical ectodermal ridge (AER), which promotes the outgrowth of the mesodermal cells of the limb bud, and in the ectopic AER of the limb buds of polydactylous diplopodia‐5 mutant embryos. In contrast, little Cx43 expression is detectable in nonridge limb ectoderm at early stages of limb development. These results suggest that Cx43 gap junctions may integrate the activity of the cells comprising the AER and compartmentalize them into a functionally distinct entity capable of directing limb outgrowth. In addition, Cx43 exhibits high expression in the posterior subridge mesoderm of the early limb bud that is growing out in response to the AER, but little expression in the anterior mesoderm. This graded distribution of Cx43 transcripts correlates with a functional gradient of gap junctional communication along the anteroposterior (AP) axis, and suggests that Cx43 gap junctions may be involved in pattern formation across the AP axis. At later stages of development, Cx43 is transiently expressed in high amounts in the precartilage condensations of the carpals and metacarpals, at a time when critical cell‐cell interactions are occurring that trigger cartilage differentiation. In contrast, in the developing limb, Cx42 is expressed exclusively by the central artery. In the remainder of the chick embryo, Cx42 is expressed in high amounts by the vessels comprising the arterial vasculature, but is not expressed by the venous vasculature. Thus, Cx42 gap junctions may be involved in specification of the arterial vasculature of the limb and embryo. Cx42, but not Cx43, is expressed in the ventricle of the heart, and by cells along the intrasclerotomal fissure that separates the rostral and caudal halves of the sclerotome of somites into distinct communication compartments. © 1994 Wiley‐Liss, Inc.
Regulation of amelogenin gene expression during tooth development
Authors: Chen Enhong , Piddington Ronald , Decker Sylvia , Park Jonathan , Yuan Zhi‐An , Abrams William R. , Rosenbloom Joel , Feldman George , Gibson Carolyn W.
Published: February 2005

The amelogenins are the predominant matrix proteins in developing enamel and are crucial for proper enamel mineralization. Transgenic mice were constructed in order to identify the segment of the amelogenin gene required for specific expression in enamel organ cells. A 3.5 kb fragment of the bovine X‐chromosomal amelogenin gene that includes a TATA box, the transcription initiation site, and 32 bp of exon 1 was linked to the βgalactosidase gene and injected into fertilized mouse eggs. Newborn transgene positive mice expressed βgalactosidase activity in developing teeth treated with the chromogenic substrate Xgal. Foci of ameloblasts were positive in newborn mice; stain intensity and number of positive ameloblasts increased in 1‐day and 2‐day postnatal mice. Some of the adjacent stratum intermedium cells also were positive in the later stages. Targeting of the transgene to the enamel organ was specific; the only other cells observed to be positive were macrophages, which have endogenous βgalactosidase activity. © 1994 Wiley‐Liss, Inc.
Heteroaggregate von Aryl‐ und Alkyllithiumreagentien: Faszinierende Strukturen mit grundlegender Bedeutung
Authors: Gossage Robert A. , Jastrzebski Johann T. B. H. , van Koten Gerard
Published: February 2005

Organolithiumverbindungen werden oft als einkernige Spezies dargestellt. Tatsächlich lagern sich diese Verbindungen aber zusammen, wobei Heteroaggregate mit verschiedenen organischen Gruppen, auch solchen mit Heteroatomen, entstehen können. Bei Reaktionen mit Organolithiumreagentien wird oft nicht beachtet, dass sich das “reine” lithiumorganische Homoaggregat in ein Heteroaggregat mit abweichender Struktur und Reaktivität umwandeln kann. Wenn das Organolithiumreagens oder das Substrat chirale Zentren enthält, kann auch diastereoselektive Selbstorganisation auftreten (die bevorzugte Bildung eines bestimmten Aggregat‐Diastereomers). Die Auswirkungen dieses Verhaltens auf Struktur und Reaktivitätsmuster von Organolithiumreagentien ist das Thema diese Kurzaufsatzes.
Cover Picture: Knotting and Threading of Molecules: Chemistry and Chirality of Molecular Knots and Their Assemblies (Angew. Chem. Int. Ed. 10/2005)
Authors: Lukin Oleg , Vögtle Fritz
Published: February 2005

Fantasy structures such as the heptafoil knot interlocked with seven trefoil knots shown in the cover picture represents a distant goal for template synthesis. Established template strategies for the synthesis of molecular knots (knotanes) and higher assemblies with twisted architectures can lead to such structures. More on the synthesis, functionalization, and properties of knots can be found in the Review by F. Vögtle and O. Lukin on page 1456 ff.
Cardiovascular lesions in Swiss mice fed a high fat — Low protein diet with and without betaine supplementation
Authors: Ball Carroll R. , Williams W. Lane , Collum Julius M.
Published: February 2005

Young adult mice of an albino stock (Taconic Swiss) were fed a hypolipotropic diet with a fat content (lard) of 28% and 8% protein (casien). The same diet containing betaine hydrochloride (2%) as a lipotropic supplement was fed to one‐half the mice.

After seven weeks of restriction to these diets (with and without betaine supplementation) pronounced lesions had developed in the hearts. These lesions consisted of myocardial necrosis and thrombi within atrial lumina. The thrombi increased progressively in size, reaching critical and lethal dimensions for 75% of the animals by 13 weeks. Atrial dilatation, as a compensating mechanism, was a typical response. Small foci of myocardial necrosis with calcification and fibrosis were common in the ventricles. All mice surviving for longer than 13 weeks showed the myocardial changes ventricles. All mice surviving for longer than 13 weeks showed the myocardial changes and the thrombosis described above. Mural necrosis was observed in the intramyocardial branches of coronary arteries but thrombosis was infreqent within these vessels. There was extreme weight loss which paralleled the onset and increasing severity of the cardiac lesions. Betaine, as a dietary lipotrope, did not prevent or alter the cardiovascular lesions.
Incidence of the ponticulus posticus of the first cervical vertebra between ages six to seventeen
Authors: Kendrick George S. , Biggs Norman L.
Published: February 2005

Lateral cephalometric radiographs of 353 young caucasoid orthodontic patients from 6 years to 17 years were examined for the presence of ponticulus posticus of the first cervical vertebra. Visualization of the posterior fossa was not obstructed and in each case the squamous occipital and posterior arch of the atlas could be clearly defined. Of the 353 subjects, 56 (15.8%) showed some degree of a ponticulus posticus. Of these, 24 (14.6%) of 164 were males and 32 (16.9%) of 189 were females, with no apparent sex differences in the occurrence of this anomaly. Those showing a ponticulus were divided on the basis of bilateral complete or incomplete and unilateral complete or incomplete. There were numerous variations in the size and location of the ossification centers in the atlanto‐occipital membrane. The youngest female with a ponticulus was six years seven months and the oldest 16 years 11 months, while the youngest male was six years four months and the oldest 16 years five months. Two females with a unilateral partial ponticulus were observed over a one to two year period. During this time a complete unilateral radiopaque ponticulus had developed.
Autoradiographic investigation of cell proliferation in the brains of rats and cats
Authors: Altman Joseph
Published: February 2005

Cell proliferation in the brains of rats and cats was investigated autoradiographically. Two young adult rats were injected intraperitoneally with 2 mc of thymidine‐H3 and killed after a two weeks' exchange period. Two adult cats were injected intraventricularly with 0.5 mc of thymidine‐H3 and killed one week later. Labeling of cell nuclei in the brain, presumed to reflect DNA turnover and cellular proliferation, was investigated. In the rats, some neuroglia cells were found labeled in all parts of the brain, suggesting a low rate of glial proliferation. In addition, circumscribed small regions with numerous labeled neuroglia and microglia cells were seen in several brain regions, suggesting the occurrence of local glial proliferative reactions in these presumably normal brains. A few apparently labeled neurons were seen in the neocortex, and a proliferative region of granule cells was identified in the dentate gyrus of the hippocampus. In the cats labeling of glia cells was highest in the midline region, near the point of injection of the radiochemical, with a gradient of decreasing number of labeled cells both laterally and in the anteroposterior direction of the neuraxis. Neurons with apparently labeled nuclei were observed in the midline cortex bilaterally in both animals. These results indicate that glia cells can multiply in the brains of young adult rats and adult cats and they support the possibility that new neurons may be formed in forebrain structures, both in rodents and carnivores.
Light and electron microscopy of the islets of langerhans of the saimiri monkey pancreas
Authors: Winborn William B.
Published: February 2005

The distribution of alpha, beta, and other islet cells in the tail of the pancreas of the Central American monkey (Saimiri sciurea) revealed by the light and electron microscopes, is similar to that occurring in man. Differentiation of acinar, islet and duct cells is based on the presence or absence of specific granules and the special morphology of the cytoplasm and its membrane systems. Conspicuous lipid droplets appear in the islets, largely confined to beta and delta cells. An “intergrade” cell is present, possessing features of both alpha and beta cells, as well as a nongranular variety of delta cells.

Nerve processes which display synaptic vesicles and clusters of mitochondria are present within the islets. Islet and acinar cells are sometime separated by connective tissue or a reticulum, as observed in light microscopy, but there may be simple apposition of their respective plasma membranes. The fine structure of this reticulum presents several levels of organization. Duct cells possess lipid masses similar to those in islet cells. These duct cells, unlike islet cells, are agranular and possess microvilli and cytoplasmic blebs, both of which show internal structures.
Fine structure of the rectal (salt‐secreting) gland of the spiny dogfish, Squalus acanthias
Authors: Bulger Ruth E.
Published: February 2005

The rectal gland of the spiny dogfish, Squalus acanthias has been described by light and electron microscopy. The cell outline shows remarkable complexity in electron micrographs. The basal plasma membrane has numerous complex infoldings and interdigitations separated by groups of mitochondria. The lateral plasma membrane also shows extensive interdigitation. The apical region demonstrates profiles of interleafing cell processes with much membrane interdigitation occurring between them but containing few mitochondria. The apical surface has microvilli which extend into the tubular lumen and are covered with nap‐like filaments. Glands of some fish were catheterized and attempts were made to correlate the fine structure of these glands with the known secretory rates. The cellular morphology of the secretory cells of the rectal gland correlates well with that seen in other ion‐transporting tissues, although some unique specializations were noted.
Fine structure of the guinea pig adrenal cortex
Authors: Sheridan M. N. , Belt W. D.
Published: February 2005

The adrenal cortex of the male guinea pig has been examined with the electron microscope. Many of the cells of the zone glomerulosa possessed bizarreshaped nuclei with frequent cytoplasmic invaginations. The internal structure of the mitochondria was entirely cristaform, the cristae being spaced at reasonably regular intervals. A rough‐surfaced endoplasmic reticulum was present in this zone only. The outer fasciculata showed an abundance of lipid in droplet from. The mitochondrial internal structure of this zone was predominantly cristaform, but the cristae were aggregated in clumps instead of being evenly spaced. Smooth‐surfaced cytoplasmic vacuoles were frequent. The inner fasciculate and the reticularis were generally similar. They differed from the above zones in that little lipid was present in droplet form and by the presence of a profusion of smooth‐surfaced cytoplasmic vacuoles which were interpreted as being homologous with the agranular endoplasmic reticulum. Mitochondria of the inner fasciculata were irregular in shape, while those of the reticularis were larger and more regular. In all zones of the cortex, the vascular channels were lined with an endothelium separated from the parenchymal cell by a space which was frequently seen to contain fibrils as well as fibroblast‐like cells.
Histology of the anterior hypophysis, thyroid and gonads of two types of dwarf mice
Authors: Bartke Andrzej
Published: February 2005

The histology of the anterior hypophysis, thyroid and gonads of dwarf (dw) and Ames dwarf (df) mutants of Mus musculus was compared. Orange G, aldehyde fuchsin and PAS stains were used to differentiate cells of the hypophysis. In both types of dwarf the anterior hypophysis was small, acidophils were lacking and the number of thyrotropic hormone producing cells was reduced. The thyroids were reduced in size, the follicles were small and some tissue was not organized into follicles. Testes were nearly normal. Ovaries were small and large follicles and corpora lutea were lacking.

Growth hormone (STH) and thyrotropic hormone (TSH) were administered to both types of dwarfs. The treatment had no effect on the anterior hypophysis but number and size of follicles in the thyroid was increased The response was greater in df dwarfs; STH and TSH had more effect than STH alone. Testes of treated mice were only slightly changed but most of the df and some dw males became fertile. The ovaries became large and functional. Thyroids of dwarfs treated with thyroxine were not changed.

It is concluded that the primary hormone deficiencies in both types of dwarf are the same, but that there are physiological differences as revealed by responses to STH and TSH treatment.
Topography of the nasal glands in rats and some other mammals
Authors: Bojsen‐Møller Finn
Published: February 2005

The topography of nasal glands in rats, guinea‐pigs, rabbits, cats, and monkeys was studied in osmium tetroxide and PAS‐stained whole mounts and ordinary sections. In rats Bowman's glands in the olfactory region were arranged in rows between the branches of the olfactory nerve. Mucous acini were only found on the rat septum in connection with Jacobson's organ, and serous acini were found on the septum posteriorly in the respiratory region, and on the lateral wall of the nasal cavity around the maxillary sinus ostium. No mixed glands were present. All the serous glands discharged their secretion through long excretory ducts into the ostium internum of the vestibule of the nose. In this area rats had 15–20 duct openings on each side. On the basis of considerations regarding airstream and pressure in the vestibule, the hypothesis is advanced that the openings act as small nozzles humidifying the inspired air by their atomized secretion. Since no serous or mucous glands in the rat open on the surface in the nasal cavity proper, it is concluded that the surface mucous sheet is derived exclusively from the goblet cells and Bowman's glands. In the other mammals the opening of the serous glands showed a similar pattern.
Mucosal reduplications associated with the ampullary portion of the major duodenal papilla in humans
Authors: Brown James Oliver , Echenberg Robert Jay
Published: February 2005

Mucosal reduplications of the ampullary mucosa in the major duodenal papilla have been found to be of two types: (1) columnar‐shaped projections apparently related to the wall of the terminal bile duct in adults only, are structures acquired postnatally; (2) leaf‐like flaps that are generally transversely oriented along the caudal wall of the ampullary space both in adults and in fetuses are congenital structures concerned in guarding the orifice of the main pancreatic duct against the incursion of back‐flowing fluids.