Biomaterial Database

[Ultrastructure of the mesencephalic visual center of the steppe turtle]. 1977

T V Davydova

A layer-by-layer study of ultrastructural synaptic organization of mesencephalic optic centre (tectum opticum) of T. horsfieldi Gray was made. The predominating type of synaptic contacts is axo-dendritic, however, there are some axo-axonic synapses which are met most frequently in the regions where polysynaptic complexes and glomeneruli (sublayer Ib, sublayer IIa and the upper zone of layer III) are disposed. Axo-somatic contacts are localized virtually in all the neuronic types. In the external layers of the tectum opticum where the terminals of optic afferents are disposed, a considerable morphological variety of nerve terminals is revealed which are distinguished not only by their ultrastructural parameters but also by the character of organization in synaptic complexes at different levels of the cortical plates of the investigated centre.

UI	MeSH Term	Description	Entries
D003336	Tectum Mesencephali	The dorsal portion or roof of the midbrain which is composed of two pairs of bumps, the INFERIOR COLLICULI and the SUPERIOR COLLICULI. These four colliculi are also called the quadrigeminal bodies (TECTUM MESENCEPHALI). They are centers for sensorimotor integration.	Corpora Quadrigemina,Lamina Quadrigemina,Quadrigeminal Plate,Tectal Plate,Commissure of Inferior Colliculus,Commissure of Superior Colliculus,Colliculus Commissure, Inferior,Colliculus Commissure, Superior,Inferior Colliculus Commissure,Inferior Colliculus Commissures,Mesencephalus, Tectum,Plate, Quadrigeminal,Plate, Tectal,Quadrigeminal Plates,Superior Colliculus Commissure,Superior Colliculus Commissures,Tectal Plates,Tectum Mesencephalus
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D013572	Synaptic Vesicles	Membrane-bound compartments which contain transmitter molecules. Synaptic vesicles are concentrated at presynaptic terminals. They actively sequester transmitter molecules from the cytoplasm. In at least some synapses, transmitter release occurs by fusion of these vesicles with the presynaptic membrane, followed by exocytosis of their contents.	Synaptic Vesicle,Vesicle, Synaptic,Vesicles, Synaptic
D014426	Turtles	Any reptile including tortoises, fresh water, and marine species of the order Testudines with a body encased in a bony or cartilaginous shell consisting of a top (carapace) and a bottom (plastron) derived from the ribs.	Sea Turtles,Terrapins,Tortoises,Sea Turtle,Terrapin,Tortoise,Turtle,Turtle, Sea,Turtles, Sea
D014795	Visual Pathways	Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.	Pathway, Visual,Pathways, Visual,Visual Pathway