bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulative ability of the prospective cardiogenic and vasculogenic areas of the primitive streak during avian gastrulation
Authors: Inagaki Takayuki , Garcia‐Martinez Virginio , Schoenwolf Gary C. 
Published: February 2005

AbstractFour types of microsurgical experiments were conducted to analyze heart and blood vessel development during gastrula stages of avian embryos, stages during which prospective cardiogenic and vasculogenic cells reside within the primitive streak. Experiments addressed whether cells not normally destined to form heart could form heart when given the opportunity to do so and vice versa; cells destined to form rostral levels of the heart (or, alternatively, head blood vessels) could form caudal levels of the heart (or, alternatively, trunk blood vessels) and vice versa; the early endoderm imparts rostrocaudal organization to the heart and associated blood vessels; and ingression of cells from the primitive streak and their subsequent migration into the mesodermal mantle is a cell‐autonomous event for migrating cells. Our results demonstrate the lability of prospective cardiogenic and vasculogenic cells of the primitive streak, both in terms of the type of mesodermal structures they are capable of forming (or of being formed from) and in terms of the rostrocaudal patterning of the cardiovascular system. In addition, our results show that cell ingression and migration is directed by environmental cues and is not a cell‐autonomous process for migrating cells. Finally, our results suggest that patterning of the cardiovascular system occurs after cells enter the mesodermal mantle, presumably through cell‐cell inductive interactions. However, the early endoderm is not the primary source of the patterning influence. What is the source remains to be established. © 1993 Wiley‐Liss, Inc.
Evidence of early topographic organization in the embryonic olivocerebellar projection: A model system for the study of pattern formation processes in the central nervous system
Authors: Paradies Michele A. , Eisenman Leonard M. 
Published: February 2005

AbstractMany projection systems within the peripheral and central nervous system are topographically organized, and it has become increasinging clear that interactions which occur during development determine the projection patterns these systems exhibit in the adult. The olivocerebellar system was chosen as a model system for this study of afferent pattern formation because it has several characteristics which lend themselves to a study of this type. Applications of horseradish peroxidase were made to both the cerebellar primordium and to the inferior olive of embryonic and neonatal mice using an in vitro perfusion system to support the tissue during the transport period. Fibers labeled after restricted olivary applications are limited to particular mediolateral regions of the cerebellum. Similarly, olivary cells retrogradely labeled after discrete cerebellar applications are restricted to particular olivary subdivisions. The results indicate that the olivocerebellar projection displays elements of topographic organization as early as E15 and that the pattern displayed is roughly comparable to that of the adult mammal. The observed trajectories of olivocerebellar fibers and their concomitant association with both Purkinje and cerebellar nuclear cells during embryonic development suggests a role for either or both cell types in the pattern formation process. © 1993 Wiley‐Liss, Inc.
Cell‐cell communication correlates with pattern formation in molting Manduca midgut epithelium
Authors: Baldwin Kate M. , Hakim Raziel S. , Stanton Gregory B. 
Published: February 2005

AbstractThe midgut epithelium of larval Manduca sexta is constructed of single goblet cells surrounded by a one‐cell‐thick reticulum of columnar cells. This pattern is expanded at each molt by the addition of new cells. Between molts, these epithelial cells are not dye coupled, even though gap junctions are present. Proliferating stem cells are dye coupled in small groups early in the molt. Then, at mid‐molt, the whole epithelium temporarily becomes dye coupled. This is when the new (expanded) pattern is being established. Later, at the end of the molt, the epithelium returns to the non‐coupled state. These results suggest that cell communication via gap junctions may play a role in cell patterning. © 1993 Wiley‐Liss, Inc.
Role of the brachial somites in the development of the appendicular musculature in rat embryos
Authors: Lee Kenneth K. H. , Sze Lung‐Yam 
Published: February 2005

AbstractDiI, a fluorescent lipophilic dye, was micro‐injected into the brachial somites of 10.5 day rat embryos to determine whether these somites can contribute cells to the development of the fore‐limb bud. The injected embryos were cultured and harvested at the 20–25‐somite stage. The dye did not interfere with somitogenesis because, at the injection site, the DiI‐labelled somites were able to differentiate into dermomyotome and sclerotome. We have analyzed cryo‐sections of 20–21‐somite stage embryos and were unable detect the presence of DiI‐labelled cells in the fore‐limb buds. However, at the 22‐somite stage, a few DiI‐positive cells were found in the proximal region of the limb bud. These labelled cells had migrated into the limb from the lateral border of the dermomyotome. From the 23‐somite stage onwards, there were even more DiI‐positive cells inside the limb. We have performed an additional set of experiments to confirm that the somitic cells do have the ability to invade and colonize the limb bud. This was achieved by first labelling newly formed somites isolated from the caudal region of 10.5 day embryos with DiI and then grafting them into corresponding regions in 8–11‐somite stage hosts. The donor somites were not orientated when they were implanted into the host. However, this did not disrupt their ability to undergo normal somitogenesis. We have detected the presence of DiI‐positive cells in the limb buds of approximately 71% of the 19–30‐somite stage embryos that have been examined. This is similar to what we obtained for the injected embryos. Nevertheless, there is one slight difference and that is the stage the somitic cells begin their invasion of the limb. For the injected embryos, migration began at the 22‐somite stage but in the transplanted embryos, it commenced as early as the 18‐somite stage. We have also investigated the myogenic potential of the fore‐limb bud at various stages of development to ascertain whether there is a correlation between the stage the somitic cells first appear in the limb bud and the stage the bud acquires the capacity to form skeletal muscles. This was realized by culturing fore‐limb buds excised from 18–30‐somite stage embryos conventionally and in the kidney capsules of adult rats. In both methods, bone and cartilage were present in all of the cultures whereas skeletal muscles were only present in cultured explants older than the 21–22‐somite stage. The appearances of skeletal muscles in the cultures correlated exactly with the stage somitic cells began their invasion of limb (as seen in the DiI injected embryos). Based upon the indirect evidence that has been obtained, we tentatively propose that the brachial musculature of the rat embryo is derived from the somites while bone and cartilage are formed by the somatopleure of the limb. © 1993 Wiley‐Liss, Inc.
Backtransplantation of chick cardiac neural crest cells cultured in LIF rescues heart development
Authors: Kirby Margaret L. , Kumiski Donna H. , Myers Tammy , Cerjan Chris , Mishima Noboru 
Published: February 2005

AbstractThe cardiac neural crest is essential for normal development of the cardiovascular system. Cardiac neural crest cells are derived from the neural folds located between the mid‐otic placodes and the caudal limit of somite 3. These crest cells can differentiate into a variety of mesenchymal cell types that support cardiovascular development, in addition to neurogenic cells. When cultured, many expressα‐smooth muscle actin or neurofilaments and lose their undifferentiated neural crest phonotype as shown by a decrease in HNK‐1 reactivity. We wanted to determine whether cultured cardiac neural crest cells maintained the potency to support normal heart development when backtransplanted into embryos lacking their native cardiac neural crest. Under usual circumstances removal of the cardiac neural crest results in 80–100% incidence of persistent truncus arteriosus. The present study report a system in which cardiac neural folds are cultured for 3 days and the cells backtransplanted into chick embryos after laser‐induced ablation of the intrinsic cardiac neural folds. Rescue of heart development was improved 50% when cultured cells were backtransplanted and almost 200% when the backtransplanted cells had been cultured in leukemia inhibitory factor (LIF). To determine whether the cultured cells are capable of following normal migratory routes, cultured homospecific cardiac neural crest cells were tagged with DiI. Initially, fluorescent cells were found concentrated around the neural tube. By the second day following backtransplantation, the cells had migrated to the circumpharyngeal crest, populated the pharyngeal arches and aortic arch arteries, and were in the region of the cardiac outflow tract. By the third day, the labeled cells had dispersed, but could be found around the neural tube, esophagus, cardiac outflow tract, and within the dorsal root ganglia. Interestingly, a cranial migration to the periphery of the eyes was also noted. With the exception of the cranial migration to the eyes, cultured and backtransplanted cardiac neural crest cells followed normal migratory pathways to the cardiac outflow tract. LIF is used for the in vitro maintenance of the pluripotential phenotype of embryonic stem cells. In an effort to understand why LIF improves the ability of cultured neural crest cells to support normal heart development, we have examined the relationship of neural crest expression of HNK‐1 antigen,α‐smooth muscle actin, and neurofilament protein in neural crest cells cultured in LIF. LIF treatment resulted in an expanded period of expression of HNK‐1 antigen, associated with a decrease in expression ofα‐smooth muscle actin. The expanded period of HNK‐1 expression is associated with proliferation of the HNK‐1 positive cell population. Expression of the neurofilament was the same in cells cultured with or without LIF. © 1993 Wiley‐Liss, Inc.
Embryonic expression patterns of the drosophila decapentaplegic gene: Separate regulatory elements control blastoderm expression and lateral ectodermal expression
Authors: Jackson P. David , Hoffmann F. Michael 
Published: February 2005

AbstractPatterns of decapentaplegic (dpp) transcripts derived from the intact gene were compared to the patterns of transcripts generated by partial dpp transgenes in Drosophila embryos. Sequences closest to the dpp coding regions, the dpp hin region, were sufficient to express lacZ‐tagged mRNA in patterns indistinguishable from the patterns of endogenous dpp expression in the dorsal and terminal cells at the blastoderm stage, in the dorsal ectoderm during germ band elongation, and in narrow stripes of ectodermal cells along the dorsal edge of the ectoderm and at the boundary between the lateral and ventral neurogenic regions during germ band shortening. The latter pattern of expression responded to the segment polarity genes naked and wingless. However, these dpp sequences were not sufficient to drive lacZ‐tagged mRNA expression in other cells normally expressing dpp, including cells in the gnathal segments, the clypeolabrum, the foregut, the midgut visceral mesoderm, and the hindgut. Two separate regulatory regions were found in the dpp hin region. A 479 bp region upstream of the promoter was necessary for the segmented pattern of expression in the lateral ectoderm and for expression in the midgut endoderm. Cis‐acting elements in the 2 kbp second intron directed expression in the dorsal and terminal regions of the blastoderm, acted on a heterologous promoter, the P‐element promoter, and responded to pattern information derived from the maternal effect dorsal/ventral patterning genes. © 1994 Wiley‐Liss, Inc.
Apoptosis in human skin development: Morphogenesis, periderm, and stem cells
Authors: Polakowska Renata R. , Piacentini Mauro , Bartlett Russell , Goldsmith Lowell A. , Haake Anne R. 
Published: February 2005

AbstractDuring human skin development, embryonic‐ and fetal‐specific periderm cells and incompletely keratinized cells are replaced by keratinocytes that differentiate while stratifying to form the fully functional epidermis. Proliferating basal cells of fetal skin also develop into epidermal appendages such as hair follicles and glands. We demonstrate that programmed cell death, not emphasized in conventional epidermal biology, has an important function in establishing the final architecture of the human epidermis and its appendages. Immunohistochemical localization of transglutaminases in fetal periderm, intermediate epidermal cells, and within appendages coincides with DNA fragmentation indicating that apoptosis is involved in deletion of these stage‐specific cells and remodeling of appendages. The data also suggest that terminal differentiation of epidermal cells might be a specialized form of apoptosis. The pattern of expression of bcl‐2, a gene associated with survival of some cells, is exclusive of the distribution patterns of markers of the cell death pathway. Bcl‐2 protein is correlated with specific morphogenetic events in hair follicles and eccrine sweat glands, and its presence in single cells of the hair follicle bulge suggests that Bcl‐2 may be a stem cell marker. © 1994 Wiley‐Liss, Inc.
Computations of post‐inductive dynamics in axolotl heart formation
Authors: Holloway David M. , Harrison Lionel G. , Armstrong John B. 
Published: February 2005

AbstractThis paper reports modelling of heart localization in the axolotl (Ambystoma mexicanum). The region of heart specification in the mesoderm defined by classical induction from the endoderm is larger than the area of final myocardial differentiation. For localizing the area of differentiation within the area of specification, we postulate a mesoderm in response to induction from the endoderm. This mechanism generates a spatial pattern for two chemicals, an activator and an inhibitor, corresponding to the area of myocardial differentiation. We postulate a diffusible chemical rescuer, which is absent in the cardiac lethal mutant, and which is a precursor to the reaction‐diffusion mechanism. The activator, inhibitor, rescuer, and product of endodermal induction are presented in an enzyme mechanism with rate equations similar to the Gierer‐Meinhardt equations. These equations were solved numerically in both one and two spatial dimensions. We have attained quantitative agreement with the experimental data for sizes of tissue regions and for times to heartbeat. Experiments modelled include wild‐type heart localization as well as both in vitro and in vivo rescue of cardiac lethal mesoderm with wild‐type mesoderm. Based upon the parameters necessary to model heart localization, we make a series of predictions. We predict: a specific profile for the endodermal inducer gradient; the possibility of producing multiple hearts in vivo; and a greater contribution to the heart from the wild‐type mesoderm for in vivo transplants with cardiac lethal mesoderm. We make some suggestions as to the possible chemical nature of the substances in the model. We indicate that the inhibitory field and mechanochemical theories are probably not as promising as reaction‐diffusion for the mechanism of heart localization. © 1994 Wiley‐Liss, Inc.
Histochemical observations on the oxidative enzyme activity and hemoglobin synthesis in the developing erythrocytic cells of the embryonic liver,
Authors: Ackerman G. Adolph 
Published: February 2005

AbstractA histochemical study of the variations in oxidative enzymes, protein‐bound amino acids (histidine, tyrosine, tryptophane, cysteine and cystine), ribonucleo‐protein and hemoglobin was made on the erythrocytic cells during the process of erythropoiesis in the embryonic liver of the rabbit.Increases in the cytoplasmic content of protein‐bound sulfhydryls and histidine were noted prior to the appearance of histochemically detectable hemoglobin and were nearly inversely related to the staining reaction for ribonucleoprotein. Changes in the oxidative enzyme activity of the developing erythrocytic elements appeared to reflect changes in the number of mitochondria present within these cells at various stages in the process of maturation. No visible changes were observed in the intensity or localization of the histochemical reactions for oxidative enzymes in the mitochondria of the erythrocytic elements except for an apparent slight increase in activity during mitosis. Two forms of hemoglobin were identified, one acid‐soluble localized to the orthochromatic normoblasts and erythrocytes of the primary erythrocytic linage and the other acid‐resistant present in the erythrocytes and late stages of the developing erythrocytic cells of the secondary erythroid series. Histochemical variations occurring during erythpoiesis were discussed in relation to biochemical data concerning hemoglobin synthesis.
A new system of melanocytes in the skin of the potto (Perodicticus potto)
Authors: Quevedo Walter C. , Montagna William 
Published: February 2005

AbstractDendritic cells which contain alkaline phosphatase and which are darkened by osmium iodide are found both in the nonpigmented and in the pigmented epidermis of the potto (Perodicticus potto). Similar cells are numerous in the pilary canals of the hair follicles. These cells, which are DOPA‐negative, are found throughout the epidermis, from the dermoepidermal junction to the stratum granulosum. In distribution and in appearance, these dendritic cells are identical to the “Langerhans” cells or to “high‐level” branched cells. Even though we have not been able to ascertain whether or not the melanotic melanocytes contain demonstrable alkaline phosphatase, we conclude, tentatively, that in the potto the dendritic cells in the basal layer, whether melanotic or amelanotic, and “high‐level” branched cells belong to the same cell line.
Arterial supply of the suprarenal gland
Authors: Merklin Robert J. 
Published: February 2005

AbstractThe arterial supply of the suprarenal gland was studied in 25 fetal or neonatal specimens consisting of both suprarenal glands, kidneys, diaphragm and associated vessels and 50 selected, adult postmortem specimens. The suprarenal arteries are derived from the aorta but the superior and inferior artery invariably become the chief supply of the diaphragm and kidney, respectively.The arteries supplying the gland are end arteries which branch profusely on the surface of the suprarenal capsule. These in turn give rise to smaller vessels in and under the capsule. At this level a unique capillary system forms vascular caps on glomerular clusters of cells. The vascular channels through the cortex are either cleft‐like sinusoids passing through or between glomerular cell groups or arteriae medullae. The former supply the cortical cells and the latter supply the medulla. The sinusoids of the inner cortex are wide, filled with red blood cells and constitute the first order of venous drainage.The inner, provisional cortex of the fetal suprarenal gland is described and contrasted with the X zone of the mouse which is completely different in histological structure and manner of appearance and disappearance.
The development and hormonal response of the autotransplanted interpubic joint in mice
Authors: Crelin E. S. 
Published: February 2005

AbstractThe ventral portion of the immature pelvis of 12‐day‐old female mice, consisting of the interpubic cartilage and the angles of the pubic bones, was excised and either autoimplanted into its original pelvic site or autotransplanted to the thoracic region. Half the number of mice with pelvic implants and half with thoracic transplants received subcutaneous injections of estrogen and relaxin prior to necropsy. All were sacrificed at 63 days of age.All the pelvic implants and the majority of thoracic transplants were present at necropsy. The grafts from the untreated mice were similar to the intact pubic symphysis ofa 63‐day‐old mature mouse both in size and morphology. The grafts from the hormone‐treated mice had undergone a pregnancy‐type response of cartilage transformation to ligamentous tissue and resorption of the medial ends of the pubic bones. The possible significance of the cells of the interpubic joint in its response to hormones is discussed.
Effects of transitory pteroylglutamic acid (PGA) deficiency on embryonic and placental development in the rat
Authors: Johnson E. Marshall , Nelson M. M. , Monie I. W. 
Published: February 2005

AbstractFemale Long‐Evans rats, were given a purified PGA‐deficient diet containing 10 mg% of the antimetabolite, 9‐methyl‐PGA, from days 8 to 10 of gestation, followed by a PGA‐supplemented diet from day 10 to autopsy. Thisregimen resulted in 18% embryonic death by day 11, 65% by day 12, and 100% by day 13 of pregnancy.No morphological differences between PGA‐deficient and control embryos were observed at nine or nine and one‐half days but ten‐day embryos showed retardation of growth and development and decreased mitosis, especially in the neural epithelium. In 11‐day PGA‐deficient embryos the cranial portion of the neural tube was markedly retarded or anomalous. PGA‐deficient embryos still living on day 12 exhibited severely retarded or abnormal development of the cranial region with moderate retardation in other areas. The placentas of PGA‐deficient embryos were normal until the twelfth or thirteenth day when vacuolization and pyknosis of giant cells in the junctional zone occurred. These changes as well as placental involution through day 16 appeared morphologically identical with those observed in placentas of embryosdestroyed surgically on day 12. PGA‐deficiency appeared primarily to affect embryonic rather than placental tissues.
Retardation of the newt limb regeneration with semicarbazide, an inhibitor of histamine formation
Authors: Deck J. David , Shapiro Samuel L. 
Published: February 2005

AbstractIt is widely known that the substance histamine is a noxious agent released from cells when they are injured. At the outset these experiments were intended to show whetherhistamine, persumably released by newt limb amputation, might also promote beginning steps in regeneration. In addition, according to a new view of the physiology of histamine, its formation metabolically by the decarboxylation of histidine is an attribute of the rapid growth of many tissues. These experiments were mainly designed to interfere with histamine production and thereby disrupt the rapid growth of the limb regenerate.Semicarbazide has been used successfully in mammals to inhibit histidine decarboxylase and decrease the rate of histamine formation. In these experiments, semicarbazide was administered to stumps of amputated newt limbs by microinfusion for many hours at a time in efforts to decrease histamine formation and retard growth.When semicarbazide was infused into the limb only in preblastemal stages of regeneration, it seemed to have no effect on the course of regeneration. When it was infused directly into the early mesenchymatous blastema, however, it retarded the expansion and differentiation of the blastema. From present evidence, it appears that histamine production may not be concerned in the initiation of limb regeneration but is probably concerned in the phase of rapid blastemal enlargement, whose primary histological attribute is cellular mitosis.