The morphology of the Mauthner’s neuron and its afferent synaptic endings are comparatively investigated in Cyclostomata, Pisces and Amphibians with special reference to the axon cap. Two evolutive lines emerged: a Batracomorphic line (B line) and a Teleosteomorphic line (T line). Steps for the B line are: Acipenseriformes, Sarcopterigyi, Urodela and larval Anura; for the T line: Brachiopterigyi, Elopomorpha, Notopteridae, Clupeomorpha, Mormiridae, Ostariophysi, Acanthopterigyi. The main morphological...
Experimental data of Marsland and Pease on the inhibitory effects of hydrostatic pressure (about 300-400 atm.) on cell division, as observed in segmenting eggs of a number of animal species, prompted me to investigate the process of embryonic morphogenesis in which cell division is brought about along with cell degeneration and movements, by means of this technique. To this aim I devised three pressurized chambers: two of them allow for direct observation of specimens, one being suitable for pressure...
The effect of high hydrostatic pressure on sea urchin embryonic development was investigated in Paracentrotus lividus with the aim of analyzing cell division and morphogenetic movements. At all stages the morphogenesis of the embryos developing in pressurized chambers (at 250—300 atm.) appeared to be more or less hindered. The least affected morphogenetic process was gastrulation, which could be accomplished although the size of archenteric cavity appeared to be reduced; the most severe disturbances...
Well differentiated neurons and glial cells are visible within globular structures of about diameter, obtained from a aggregation of disaggregated olfactory bulbs of chicken embryos, 10 days' incubation old, and cultivated in the “rotating shaker” for 20 days. Particularly recognizable are mitral cells and granule cells (amacrine). Electron microscopy reveals different kinds of synaptic profiles: axo-dendritic, axo-somatic and dendro-dendritic. Of particular interest is the finding in the cultivated...
Studies were performed on spherules of approximately in diameter obtained from the reaggregation of dissociated bulbar acoustic regions of 11-days incubation chick embryos. These spherules were cultured for 15 days and then prepared for electron microscope observations. We did ascertain that cellules of the nucleus magnocellularis are able to differentiate also in these in vitro conditions of anatomical and functional isolation and without any possibility of a root coclear fibers connection. Moreover,...
Preliminary observations reported hereafter on the morphogenesis of Amphibian embryos (Anura) show that hydrostatic pressure of an order of magnitude of 200-300 atm. brings about partial inhibition of gastrulation (i.e. morphogenesis does not proceed beyond initial dorsal lip formation), whereas in embryos to which pressure was applied at the neurula stage (just elevated neural folds) neural tube fusion is accomplished along a pattern superimposable to that of the control embryos, grown at normal...
Embryonic rudiments of the cerebellum of 11 days old chick embryos were dissociated with trypsin; numerous spherules or globets of 100-300 µ diameter were re-aggregated after some hours; these were cultivated in vitro in a giratory shaker for a maximum of 21 days. Ultra thin sections for electron microscopy observation were made. Purkinje cells, granule cells and Golgi cells are recognizable. Various parts of these globets were found rich in synaptic knobs and other simple synaptic patterns as well...
The cells of the retina of chick embryo at the 4th day of incubation were isolated by the trypsin disgregation tecnique. These cells were let reaggregate into spherules (about 200 diam.) and then cultivated in vitro for up to 25 days. By means of the electron-microscope the synapses were studied. The result is that the synaptic ribbons of photoreceptors and of the bipolar cells are specific structures, intrinsically determined in the early embryo, related to the modality of release of the chemical...
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