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Developmental Anatomy (developmental + anatomy)
Selected AbstractsDevelopmental Anatomy and Morphology of the Ovule and Seed of Heliconia (Heliconiaceae, Zingiberales)PLANT BIOLOGY, Issue 1 2006D. G. Simão Abstract: The developmental anatomy and morphology of the ovule and seed in several species of Heliconia were investigated as part of an embryological study of the Heliconiaceae and to provide a better understanding of their relationships with the other families of the Zingiberales. Heliconia species have an ovule primordium with an outer integument of both dermal and subdermal origin. The archesporial cell is divided into a megasporocyte and a single parietal cell, which in turn are divided only anticlinally to form a single parietal layer, disintegrating later during gametogenesis. The embryo sac was fully developed prior to anthesis. In the developing seed, the endosperm was nuclear, with wall formation in the globular stage; a nucellar pad was observed during embryo development, but later became compressed. The ripe fruit contained seeds enveloped by a lignified endocarp that formed the pyrenes, with each pyrene having an operculum at the basal end; the embryo was considered to be differentiated. Most of these characteristics are shared with other Zingiberales, although the derivation of the operculum from the funicle and the formation of the main mechanical layer by the endocarp are unique to the Heliconiaceae. [source] Developmental anatomy of reeler mutant mouseDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2009Yu Katsuyama The reeler mouse is one of the most famous spontaneously occurring mutants in the research field of neuroscience, and this mutant has been used as a model animal to understand mammalian brain development. The classical observations emphasized that laminar structures of the reeler brain are highly disrupted. Molecular cloning of Reelin, the gene responsible for reeler mutant provided insights into biochemistry of Reelin signal, and some models had been proposed to explain the function of Reelin signal in brain development. However, recent reports of reeler found that non-laminated structures in the central nervous system are also affected by the mutation, making function of Reelin signal more controversial. In this review, we summarized reported morphological and histological abnormalities throughout the central nervous system of the reeler comparing to those of the normal mouse. Based on this overview of the reeler abnormalities, we discuss possible function of Reelin signal in the neuronal migration and other morphological events in mouse development. [source] Developmental anatomy of seedlings of Indodalzellia gracilis (Podostemaceae)PLANT BIOLOGY, Issue 5 2010S. Koi Abstract In Tristichoideae, aquatic angiosperms in the family Podostemaceae, Terniopsis, Tristicha, Indotristicha and Cussetia have creeping roots with flanking (sub)cylindrical shoots, while Dalzellia is rootless and has crustose shoots. Indodalzellia gracilis, sister to a clade of Dalzellia zeylanica and Indotristicha ramosissima, has subcrustose shoots on the side of creeping roots, suggesting that I. gracilis may be a key species to reveal how saltational evolution of the body plan occurred in these three species. We investigated developmental morphology of I. gracilis seedlings grown in culture, using scanning electron microscopy and semi-thin serial sections. As in D. zeylanica, the plumular apical meristem in the seedling gives rise to two shoot apical meristems, which develop into horizontal subcrustose shoots with dorsal and marginal leaves. Neither radicle nor adventitious root is produced from the hypocotyl, but an adventitious root arises endogenously from the juvenile shoot and from some shoots of adult plants. These results, together with the phylogenetic relationships, suggest that the Indodalzellia seedling evolved by loss of the adventitious root derived from the hypocotyl, appearance of shoots in the axil of cotyledons, and appearance of adventitious roots from adventitious shoots. The difference in place of origin of the root between Indodalzellia and I. ramosissima suggests differing evolutionary origin of the root in Tristichoideae. [source] Developmental anatomy of lampreysBIOLOGICAL REVIEWS, Issue 1 2010Michael K. Richardson Lampreys are a group of aquatic chordates whose relationships to hagfishes and jawed vertebrates are still debated. Lamprey embryology is of interest to evolutionary biologists because it may shed light on vertebrate origins. For this and other reasons, lamprey embryology has been extensively researched by biologists from a range of disciplines. However, many of the key studies of lamprey comparative embryology are relatively inaccessible to the modern scientist. Therefore, in view of the current resurgence of interest in lamprey evolution and development, we present here a review of lamprey developmental anatomy. We identify several features of early organogenesis, including the origin of the nephric duct, that need to be re-examined with modern techniques. The homologies of several structures are also unclear, including the intriguing subendothelial pads in the heart. We hope that this review will form the basis for future studies into the phylogenetic embryology of this interesting group of animals. [source] Cell fate and timing in the evolution of neural crest and mesoderm development in the head region of amphibians and lungfishesACTA ZOOLOGICA, Issue 2009Rolf Ericsson Abstract Our research on the evolution of head development focuses on understanding the developmental origins of morphological innovations and involves asking questions like: How flexible (or conserved) are cell fates, patterns of cell migration or the timing of developmental events (heterochrony)? How do timing changes, or changes in life history affect head development and growth? Our ,model system' is a comparison between lungfishes and representatives from all three extant groups of amphibians. Within anuran amphibians, major changes in life history such as the repeated evolution of larval specializations (e.g. carnivory), or indeed the loss of a free-swimming larva, allows us to test for developmental constraints. Cell migration and cell fate are conserved in cranial neural crest cells in all vertebrates studied so far. Patterning and developmental anatomy of cranial neural crest and head mesoderm cells are conserved within amphibians and even between birds, mammals and amphibians. However, the specific formation of hypobranchial muscles from ventral somitic processes shows variation within tetrapods. The evolution of carnivorous larvae in terminal taxa is correlated with changes in both pattern and timing of head skeletal and muscle development. Sequence-heterochronic changes are correlated with feeding mode in terminal taxa and with phylogenetic relatedness in basal branches of the phylogeny. Eye muscles seem to form a developmental module that can evolve relatively independently from other head muscles, at least in terms of timing of muscle differentiation. [source] An ontology of human developmental anatomyJOURNAL OF ANATOMY, Issue 4 2003Amy Hunter Human developmental anatomy has been organized as structured lists of the major constituent tissues present during each of Carnegie stages 1,20 (E1,E50, ,8500 anatomically defined tissue items). For each of these stages, the tissues have been organized as a hierarchy in which an individual tissue is catalogued as part of a larger tissue. Such a formal representation of knowledge is known as an ontology and this anatomical ontology can be used in databases to store, organize and search for data associated with the tissues present at each developmental stage. The anatomical data for compiling these hierarchies comes from the literature, from observations on embryos in the Patten Collection (Ann Arbor, MI, USA) and from comparisons with mouse tissues at similar stages of development. The ontology is available in three versions. The first gives hierarchies of the named tissues present at each Carnegie stage (http://www.ana.ed.ac.uk/anatomy/database/humat/) and is intended to help analyse both normal and abnormal human embryos; it carries hyperlinked notes on some ambiguities in the literature that have been clarified through analysing sectioned material. The second contains many additional subsidiary tissue domains and is intended for handling tissue-associated data (e.g. gene-expression) in a database. This version is available at the humat site and at http://genex.hgu.mrc.ac.uk/Resources/intro.html/), and has been designed to be interoperable with the ontology for mouse developmental anatomy, also available at the genex site. The third gives the second version in GO ontology syntax (with standard IDs for each tissue) and can be downloaded from both the genex and the Open Biological Ontology sites (http://obo.sourceforge.net/) [source] Prenatal Development of the Human Epicardiac GangliaANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2009I. Saburkina Summary The aim of this study was to determine the developmental anatomy of intrinsic cardiac ganglia with respect to epicardiac ganglionated nerve plexus in the human fetuses at different gestation stages. Twenty fetal hearts were investigated applying a technique of histochemistry for acetylcholinesterase to visualize the epicardiac neural ganglionated plexus with its subsequent examinations on total (non-sectioned) hearts. Most epicardiac ganglia embodied multilayered neurons and were oval in shape, but some ganglia involved neurons lying in one layer or had the irregular appearance because of their extensions along inter-ganglionic nerves. The mean ganglion area of fetuses at gestation stages of 15,40 weeks was 0.03 ± 0.008 mm2. The largest epicardiac ganglia, reaching in area 0.4 mm2, were concentrated on the dorsal surface of both atria. The particular fused or "dual" ganglia were identified at the gestation stages of 23,40 weeks, but they composed only 2.3 ± 0.7% of all found epicardiac ganglia. A direct positive correlation was determined between the fetal age and the ganglion area (mm2) as well as between the fetal age and the number of inter-ganglionic nerves. The revealed appearance of epicardiac ganglia in the human fetuses at 15,40 weeks of gestation confirms their prenatal development and presumable intrinsic remodelling. [source] Developmental anatomy of lampreysBIOLOGICAL REVIEWS, Issue 1 2010Michael K. Richardson Lampreys are a group of aquatic chordates whose relationships to hagfishes and jawed vertebrates are still debated. Lamprey embryology is of interest to evolutionary biologists because it may shed light on vertebrate origins. For this and other reasons, lamprey embryology has been extensively researched by biologists from a range of disciplines. However, many of the key studies of lamprey comparative embryology are relatively inaccessible to the modern scientist. Therefore, in view of the current resurgence of interest in lamprey evolution and development, we present here a review of lamprey developmental anatomy. We identify several features of early organogenesis, including the origin of the nephric duct, that need to be re-examined with modern techniques. The homologies of several structures are also unclear, including the intriguing subendothelial pads in the heart. We hope that this review will form the basis for future studies into the phylogenetic embryology of this interesting group of animals. [source] Communications between the palmar digital branches of the median and ulnar nerves: A study in human fetuses and a review of the literature,CLINICAL ANATOMY, Issue 2 2010Nadire Unver Dogan Abstract In this study, median nerves (MNs) and ulnar nerves (UNs) were dissected in 200 palmar sides of hands (left and right) of 100 (50 male, 50 female) spontaneously aborted fetuses with no detectable malformations. The fetuses, whose gestational ages ranged from 13 to 40 weeks, were dissected under an operating microscope. The MN divided first into a lateral ramus and a medial ramus and then formed a common digital nerve. The first common digital nerve trifurcated in all of the studied cases. The branching patterns were classified into two types (Type 1 and Type 2) based on the relationship with the flexor retinaculum (behind/distal of it). A communication branch between the UNs and MNs in the palmar surface of the hand was found in 59 hands (29.5%). The proper palmar digital nerves were numbered from p1 to p10, starting from the radial half of the thumb to the ulnar half of the little finger, and these nerves exhibited six types of variations. The present data obtained from human fetuses will aid in elucidating the developmental anatomy of the nervous system and provide hand surgeons with a more complete anatomical picture to help them to avoid iatrogenic injuries. Clin. Anat. 23:234,241, 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||