Developmental Features (developmental + feature)

Distribution by Scientific Domains

Selected Abstracts

Spontaneous mutation in mice provides new insight into the genetic mechanisms that pattern the seminal vesicles and prostate gland

Paul C. Marker
Abstract The seminal vesicles and prostate gland are anatomically adjacent male sex-accessory glands. Although they arise from different embryonic precursor structures and express distinct sets of secretory proteins, these organs share common features in their developmental biology. A key shared developmental feature is the elaboration of complex secretory epithelia with tremendous surface area from simple precursor structures with juxtaposed epithelial and mesenchymal cells. In this study, new insight into the nature of the biological processes that underlie glandular morphogenesis is achieved by analyzing the phenotypes present in mice that harbor a spontaneous mutation, seminal vesicle shape (svs), previously identified for causing altered seminal vesicle morphology in adults. An examination of seminal vesicle development in svs mice provides the first evidence that the concurrent processes of epithelial branching and epithelial infolding are distinct processes under separate genetic control. It also provides the first direct evidence that the thickness and topology of the smooth muscle layer in the seminal vesicles are determined by interaction with the glandular epithelium during the branching process. In addition, the seminal vesicle phenotype in svs mice is shown to phenocopy the morphologic form present in certain other mammals such as the guinea pig, raising the possibility that the svs mutation is the sort of variant that arises during evolution. By also including an investigation of the prostate gland, this study also identifies previously unrecognized phenotypes in svs prostates, including increased gland size and dramatically reduced levels of branching morphogenesis. Finally, this study advances the goal of identifying the svs gene by mapping the svs mutation relative to known molecular markers and testing Fgfr2 as a candidate gene. The finding that the svs mutation maps to a genomic region syntenic to a region frequently deleted in human prostate tumors, together with the prostatic phenotype present in svs mice, further raises the interesting possibility that the svs mutation will identify a candidate prostate tumor suppressor gene. Developmental Dynamics 226:643,653, 2003. © 2003 Wiley-Liss, Inc. [source]

Brachiola algerae Spore Membrane Systems, their Activity During Extrusion, and a New Structural Entity, the Multilayered Interlaced Network, Associated with the Polar Tube and the Sporoplasm

ABSTRACT. The microsporidial genus, Brachiola, contains three species: the type species Brachiola vesicularum (identified from an AIDS patient) and two species transferred from the genus Nosema, becoming Brachiola connori and Brachiola algerae. A developmental feature of the genus Brachiola is the "thickened" plasmalemma from sporoplasm through sporoblast stage. The sporoplasm has been reported to have a thick plasmalemma at 1-h postextrusion. The purpose of this investigation was to observe B. algerae spores before, during and after germination to determine if the plasmalemma is thick at the point of extrusion and if not, when and how it forms. New understandings regarding the polar filament position inside the spore, places it outside the sporoplasm proper with the sporoplasm limiting membrane imaginations surrounding it. These invaginations, present a possible location for aquaporins. The multilayered interlaced network (MIN), a new organelle (possibly of Golgi origin from the sporoblast), was observed inside the spore and sporoplasm; it formed an attachment to the end of the extruded polar tube and contributed to the thickening of the sporoplasm plasmalemma. A thin "unit limiting membrane", present on the sporoplasm at the time of extrusion, is connected to the MIN by many cross-connections forming the "thick blistered" surface by 30 min-postextrusion. [source]

Epileptiform Activity Induced by Pharmacologic Reduction of M-Current in the Developing Hippocampus in Vitro

EPILEPSIA, Issue 1 2006
Fernando Peña
Summary:,Purpose: Benign familial neonatal convulsions (BFNCs), an inheritable epilepsy that occurs in neonates but not in adults, is caused by hypofunctional mutations in genes codifying for the M-type K+ current. In an attempt to develop an in vitro model of this disease, we tested whether blocking M-current with linopirdine induces epileptiform activity in brain slices from animals of different ages. Methods: Horizontal hippocampus,entorhinal cortex slices were obtained from neonatal (1,2 weeks after birth) and adult (8,9 weeks after birth) rats. Extracellular field recordings of the CA1 region were performed. After recording control conditions, linopirdine was added to the bath, and field activity was recorded continuously for 3 h. 4-Aminopyridine, a drug commonly used to induce epileptiform activity in vitro, was used as a control for our experimental conditions. Results: Bath perfusion of linopirdine induced epileptiform activity only in slices from neonatal rats. Epileptiform activity consisted of interictal-like and ictal-like activity. In slices from adult rats, linopirdine induced erratic interictal-like activity. In contrast, 4-aminopyridine was able to induce epileptiform activity in slices from both neonatal and adult rats. Conclusions: We demonstrated that blockade of M-current in vitro produces epileptiform activity with a developmental pattern similar to that observed in BNFCs. This could be an in vitro model that can be used to study the cellular mechanisms of epileptogenesis and the developmental features of BFNCs, as well as to develop some therapeutic strategies. [source]

Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause III

Article first published online: 22 JAN 200
Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause III. The embryo, surrounded by a transparent vitelline envelope, is in the pre-hatching stage. A prominent eye and part of the pigmented body and tail are apparent. Why annual fishes? Annual fishes (Order Cyprinodontiformes) are a special kind of teleost, found in Africa and South America, with developmental strategies closely related to their life cycle. These fishes inhabit temporary pools that undergo drying during summer, when all adults die. The embryos remain buried in the bottom mud and are resistant to desiccation. In the subsequent rainy season they hatch a few hours after the pool is flooded and a new reproductive cycle begins. This developmental pattern is characterized by the presence of a unique stage between cleavage and embryogenesis, dispersion-aggregation of blastomeres and because the embryos show reversible developmental arrests (diapauses) at different stages. Annual fish embryos are transparent, large, hardy and easy to maintain in the laboratory. Adults show continuous production of eggs and juveniles reach sexual maturity a few weeks after hatching (an unusual condition in fishes). Their particular developmental features confer unique opportunities for research on cell behavior during early development, the effect of environmental factors on development, the regulation of diapauses and the mechanisms involved in sex determination, among others topics. Image provided by Nibia Berois, Universidad de la República, Montevideo, Uruguay. [source]

Transformation of the pectoral girdle in the evolutionary origin of frogs: insights from the primitive anuran Discoglossus

Pavla Havelková
Abstract Using cleared-and-stained whole mounts and computer-aided three-dimensional reconstructions made from serial histological sections, we studied the development of the pectoral girdle in Discoglossus pictus, an extant member of an ancient frog lineage, represented for example by Eodiscoglossus from the Middle Jurassic to Early Cretaceous periods in Europe. Basic developmental features were compared with those of extinct Temnospondyli, considered to be the most probable anuran ancestors, and with Triadobatrachus, an early Triassic proanuran. In the endochondral girdle, the separate scapula and coracoid of Discoglossus and other anurans (completed by suprascapular and procoracoid cartilages) evolved from the compact scapulocoracoid of temnospondyls by paedomorphosis. In parallel, the dermal ossifications of the girdle were reduced to a small clavicle and cleithrum. The overall reduction in ossification of the anuran pectoral girdle supports the hypothesis of a paedomorphic origin for Anura. The almost simultaneous appearance of dermal and endochondral ossifications may be explained by the accumulation of developmental events during a short, distinct metamorphosis (which did not occur in neotenic temnospondyls living permanently in water). The sternal elements seem to be neomorphs for the most part, which help to cushion the shock of landing in jumping anurans but which also evolved as functional substitutes (insertion area for the pectoralis muscles) of the temnospondyl interclavicle. [source]

Patterns of carpal development among anuran amphibians

Marissa Fabrezi
Abstract The unity and diversity of developmental processes in the vertebrate limb have singular importance in the interpretation of evolutionary hypotheses of tetrapod diversification. In anurans, the intraordinal diversity of forelimbs seems to be related to the fusion of distal carpals, whereas proximal carpals are invariable. However, there are different ontogenetic pathways involved in the differentiation of proximal carpals. This study presents a comparative analysis of early developmental features in one archeobatrachian and 23 neobatrachian species representing five families and explores the variability in the differentiation of carpal cartilages. We found new evidence supporting the presence of an embryonic intermedium that incorporates with the ulnare. Difference between the pipid Xenopus and the neobatrachians is interpreted as a change in the rate of differentiation of Distal Carpal 5 that does not affect the developmental pattern of digits. The developmental variability exhibited by the intermedium, radiale, and Element Y is combined in patterns that converge on the same adult carpal morphology among neobatrachians; these patterns appear to contain potentially useful phylogenetic information. J. Morphol. 249:210,220, 2001. © 2001 Wiley-Liss, Inc. [source]

Immunohistochemical and hodological characterization of calbindin-D28k-containing neurons in the spinal cord of the turtle, Pseudemys scripta elegans

Ruth Morona
Abstract Neurons and fibers containing the calcium-binding protein calbindin-D28k (CB) were studied by immunohistochemical techniques in the spinal cord of adult and juvenile turtles, Pseudemys scripta elegans. Abundant cell bodies and fibers immunoreactive for CB were widely and distinctly distributed throughout the spinal cord. Most neurons and fibers were labeled in the superficial dorsal horn, but numerous cells were also located in the intermediate gray and ventral horn. In the dorsal horn, most CB-containing cells were located in close relation to the synaptic fields formed by primary afferents, which were not labeled for CB. Double immunohistofluorescence demonstrated distinct cell populations in the dorsal horn labeled only for CB or nitric oxide synthase, whereas in the dorsal part of the ventral horn colocalization of nitric oxide synthase was found in about 6% of the CB-immunoreactive cells in this region. Choline acetyltransferase immunohistochemistry revealed that only about 2% of the neurons in the dorsal part of the ventral horn colocalized CB, whereas motoneurons were not CB-immunoreactive. The involvement of CB-containing neurons in ascending spinal projections to the thalamus, tegmentum, and reticular formation was demonstrated combining the retrograde transport of dextran amines and immunohistochemistry. Similar experiments demonstrated supraspinal projections from CB-containing cells mainly located in the reticular formation but also in the thalamus and the vestibular nucleus. The revealed organization of the neurons and fibers containing CB in the spinal cord of the turtle shares distribution and developmental features, colocalization with other neuronal markers, and connectivity with other tetrapods and, in particular with mammals. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source]