The middle ear cavities of crocodilians have complex connections with the pharyngeal lumen, including lateral and median components which both open into a single chamber located on the dorsal midline of the pharynx. This chamber and the surrounding soft-tissue is herein termed the median pharyngeal valve. In the American alligator (Alligator mississippiensis) this valve opens, for a duration of 0.
View Article and Find Full Text PDFLizard ears are coupled across the pharynx, and are very directional. In consequence all auditory responses should be directional, without a requirement for computation of sound source location. Crocodilian ears are connected through sinuses, and thus less tightly coupled.
View Article and Find Full Text PDFIn early tetrapods, it is assumed that the tympana were acoustically coupled through the pharynx and therefore inherently directional, acting as pressure difference receivers. The later closure of the middle ear cavity in turtles, archosaurs, and mammals is a derived condition, and would have changed the ear by decoupling the tympana. Isolation of the middle ears would then have led to selection for structural and neural strategies to compute sound source localization in both archosaurs and mammalian ancestors.
View Article and Find Full Text PDFPhysiological and anatomical studies have suggested that alligators have unique adaptations for spatial hearing. Sound localization cues are primarily generated by the filtering of sound waves by the head. Different vertebrate lineages have evolved external and/or internal anatomical adaptations to enhance these cues, such as pinnae and interaural canals.
View Article and Find Full Text PDFMany fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above.
View Article and Find Full Text PDFThe stomach of the American lobster (Homarus americanus) is located in the cephalothorax, between the rostrum and the cervical groove. The anterior end of the stomach is defined by the mouth opening and the posterior end by the bottom of the pylorus. Along the dorsal side of the stomach lies the stomatogastric nervous system (STNS).
View Article and Find Full Text PDFStudies of vertebrate brain evolution have focused primarily on patterns of gene expression or changes in size and organization of major brain regions. The Mauthner cell, an important reticulospinal neuron that functions in the startle response of many species, provides an opportunity for evolutionary comparisons at the cellular level. Despite broad interspecific similarities in Mauthner cell morphology, the motor patterns and startle behaviors it initiates vary markedly.
View Article and Find Full Text PDFWith the goal of understanding how nervous systems produce activity and respond to the environment, neuroscientists turn to model systems that exhibit the activity of interest and are accessible and amenable to experimental methods. The stomatogastric nervous system (STNS) of the American lobster (Homarus americanus; also know was the Atlantic or Maine lobster) has been established as a model system for studying rhythm generating networks and neuromodulation of networks. The STNS consists of 3 anterior ganglia (2 commissural ganglia and an oesophageal ganglion), containing modulatory neurons that project centrally to the stomatogastric ganglion (STG).
View Article and Find Full Text PDFWhile most actinopterygian fishes perform C-start or S-start behaviors as their primary startle responses, many elongate species instead use a withdrawal movement. Studies of withdrawal have focused on the response to head-directed or nonspecific stimuli. During withdrawal, the animal moves its head back from the stimulus, often resulting in several tight bends in the body.
View Article and Find Full Text PDFBackground: We report the use of two novel nuclide agents, Technetium-99m (99Tc)sestamibi (MIBI) and indium-111 (In-111) octreotide, in comparison with conventional computed tomography (CT) imaging in a patient with metastatic Ewing's sarcoma (ES) before and after high dose chemotherapy with autologous peripheral stem cell transplantation (PSCT). MIBI is taken up actively by metabolically active tumor cells. Octreotide, a somatostatin analog, binds specifically to somatostatin receptors.
View Article and Find Full Text PDFUnlabelled: We performed this study in an attempt to reconcile the differences with respect to 67Ga uptake as a function of tumor grade and type in the literature, as well as to determine the sensitivity of 201Tl uptake in both Hodgkin's and non-Hodgkin's lymphoma.
Methods: Thirty-six (9 with low-grade lymphoma, 11 with intermediate-grade lymphoma, 4 with high-grade lymphoma and 12 with Hodgkin's lymphoma) patients underwent both 67Ga and 201Tl scintigraphy. Biopsies were done on all patients.
Fingerprints from 200 women with histologically proven breast cancer (case group) were compared to fingerprints from 138 women with no history of any malignant disease (control group). Of the patterns analyzed, four were significantly associated with breast cancer: accidentals, transitionals, angled ulnar loops, and horizontal ulnar loops. A fifth print, the angled radial loop, was found to be of borderline importance as an independent predictor of breast cancer.
View Article and Find Full Text PDFLactoferrin has been reported to inhibit the production of colony-stimulating factor (CSF); thus we sought to study its possible effects on myelopoiesis in vivo. The characteristics of rebound myelopoiesis in C57BL mice injected with a sublethal dose of cyclophosphamide (CY) were used to test lactoferrin for any granulopoietic activity. An experimental group received daily injections of 50 micrograms of human lactoferrin beginning 24 hr after CY injections.
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