(1) The fertilization reaction of echinoderm eggs (Lytechinus pictus, a sea urchin, and Dendraster excentricus, a sand dollar) was followed with intracellular electrodes.
(2) I describe the anatomy and fine structure of the echinoderm ovary, with emphasis on both the cellular relationships of the germ line cells to the somatic cells of the inner epithelium, and on the neuromuscular systems.
(3) In echinoderms, which stop at interphase, no such a factor has so far been found.
(4) In frogs and mammals, the oocytes are arrested at the second metaphase of meiosis whereas in echinoderms they are blocked later, at the pronucleus stage.
(5) An examination of Antp class homeo box genes in deuterostomes indicates that a chromosomal duplication has taken place in the evolutionary line leading to the vertebrates after the divergence of the echinoderms.
(6) Next, we present some features of the described processes for sugar and amino acid transport in the tubular portion of gastrointestinal tracts of three major invertebrate groups: echinoderms, molluscs, and arthropods.
(7) The emonctory structures, functions and stereotype and their component parts are studied in protists, spongia, coelenterata and coelomata: lower worms, annelids, their hyponeurian descendents (arthropods, molluses) and epineurian descedents echinoderms and protochordates (Stomochordata, Tunicata, Cephalochordata).
(8) The transition from the single creatine kinase locus, characteristic of certain echinoderms, to the two creatine kinase loci which are orthologous to those present in all vertebrates, occurred early in the chordate line.
(9) These features are characteristic of sea urchin (Echinoderm) spines which are composed of ornately formed calcite crystals covered by an epithelium.
(10) The echinoderms Asterias rubens and Solaster papposus (Class Asteroidea) metabolize injected [4(-14)C]cholest-5-en-3beta-ol to produce labelled 5alpha-cholestan-3beta-ol and 5alpha-cholest-7-en-3beta-ol.
(11) Echinoderm oocyte maturation is reviewed and a description of the ultrastructural, biochemical and molecular biological changes thought to occur during this process is presented.
(12) Another round of gene duplication, involving Wnt-3, -5, -7, and -10, occurred after the echinoderm lineage arose, on the ancestral lineage of jawed vertebrates.
(13) Changes in the distribution and organizational state of actin in the cortex of echinoderm eggs are believed to be important events following fertilization.
(14) Small numbers are present in algae, ferns, conifers, sponges, echinoderms, other marine animals, and arthropods.
(15) However, recent work which used colchicine to block microtubule assembly in the eggs of two other echinoderms, S. purpuratus and D. excentricus, has raised serious questions about the generality of this role for spindle microtubules.
(16) It would seem that these epitope regions have been strongly conserved since the epitope region is also present in the phosphoprotein of echinoderm teeth.
(17) Both species differences and species similarities in the agglutination were found in spermatozoa of the echinoderm, the sea urchin and the starfish.
(18) Furthermore, during meiotic maturation in these echinoderm and amphibian oocytes, this is followed by activation of many of the same protein-serine (threonine) kinases that are stimulated when quiescent mammalian somatic cells are prompted with mitogens to traverse from G0 to G1 phase.
(19) One of these fragments contains the active site and is identical at all sequenced residues with the corresponding region from the echinoderm sperm flagellar creatine kinase, and is 96% homologous with both chicken and rat B creatine kinase subunits.
(20) A significant feature of the early development of fertilized echinoderm and amphibian eggs and germinating seed embryos is the utilization of genetic information that has been previously transcribed during oogenesis and seed ripening.
Umbo
Definition:
(n.) The boss of a shield, at or near the middle, and usually projecting, sometimes in a sharp spike.
(n.) A boss, or rounded elevation, or a corresponding depression, in a palate, disk, or membrane; as, the umbo in the integument of the larvae of echinoderms or in the tympanic membrane of the ear.
(n.) One of the lateral prominence just above the hinge of a bivalve shell.
Example Sentences:
(1) The position, displacement and phase angle of the rotation axis of the ossicles was calculated based on the displacement and phase angle of the umbo, malleus head and lenticular process.
(2) The bending will also affect the displacements transmitted to the ossicular load, and introduce significant errors into estimates of such displacements based on measurements of umbo displacement even at frequencies as low as a few kHz.
(3) The umbo region may represent the center of superficially radial dispersion.
(4) The epithelial migration center was found at the region of umbo, manubrium, and the short process of the malleus.
(5) It is demonstrated that the rotation angels can not account for the measured movement of the umbo, which leads to the conclusion that for static high pressure levels the classical hypothesis of rotation around a fixed axis has to be abandoned.
(6) There is a small area we have termed the "slow zone", located anterior and inferior to the umbo, that has comparatively fewer patches and where ink dots can remain static for several weeks.
(7) This attachment is most intimate at the level of the umbo and becomes progressively more tenuous as the short process is approached.
(8) It is shown further that a linear relationship between umbo displacement and volume displacement exists.
(9) The acoustically estimated "drum location" generally lay between the optically determined vertical planes containing the TOD and the umbo.
(10) The displacement of the umbo is compared to other work.
(11) All of the modifications (except the perforation) had a minimal effect on umbo displacement; this seems to imply that the pars flaccida has a minor acoustic role in human beings.
(12) Due to the gliding movement in the malleus-incus joint, this motion changes at the umbo into outward rotation, counteracting the tensor tympani muscle.
(13) When the motion is rotational the position of the axis of rotation shifts with frequency, the shifts are so large that the axis can lie near the umbo so that amplitudes at the processus lateralis are larger than at the umbo.
(14) The umbo moved piston-like at 0.1-0.8 kHz and 2.6-4.5 kHz but in an ellipse at 1.0-2.4 kHz.
(15) The vibration amplitude and phase angle of the umbo, malleus head, lenticular process and stapes head were measured at 19 frequencies between 0.1 kHz and 4.5 kHz.
(16) The malleus head showed elliptical movement with its long axis anteriorly tilted around 45 degrees from the direction of the umbo vibration at 0.1 kHz.
(17) As a result of the bending, the frequency response at the umbo at high frequencies displays much higher amplitudes and larger phase lags than when the manubrium is rigid.
(18) The effects of aditus blockage, decrease of tympanic cavity volume, and resection of the tensor tympani muscle on umbo displacement were studied in human temporal bones using a new non-contacting video measuring system.
(19) The umbo, lenticular process and stapes head vibrated parallel at lower frequencies.
(20) The three-dimensional movements of the umbo, the proc.