Raimundo Villegas

Learn More
There are several methods by which the structure of a cell may be studied. The electron microscope makes it possible to visualize details of the ultrastructure, and to resolve these details with a resolution of 10 ~. Membranes may also be characterized in terms of the molecules which diffuse across them, leading to a resolution which may be an order of(More)
The present work deals with the search and identification of the molecule or combination of molecules, present in a medium conditioned by cultured rat-sciatic nerves (CM), able to cause neuronal differentiation of PC12 cells. The molecular mass range of the active fraction, as well as the thermostability and heparin affinity of the active component found in(More)
The receptor-site for the sea anemone toxin II from Anemonia sulcata (ATX) and its functional relationship with the Na+ channel were studied in plasma membrane preparations from lobster walking leg nerves. The modification of the 22Na influx by ATX was determined in membrane vesicles and in proteoliposomes prepared by reconstitution of detergent-extracted,(More)
The present work deals with the finding and characterization of a neurotrophic factor present in serum-free Dulbecco's modified Eagle's medium in which rat sciatic nerves previously cultured for 9 days were maintained for 24 h. This sciatic nerve conditioned medium (SNCM) produced neuronal differentiation and neurite outgrowth on PC12 cells, as well as(More)
In fifty-seven resting nerve fibers of the squid Sepioteuthis sepioidea impaled from outside to inside, three potential difference (PD) levels were recorded. In twelve nerve fibers the position of the tip of the micropipette, when it was recording one of the I'D levels, was labeled with carmine, and the minute spot of dye was localized histologically. The(More)
The work of Young (1) on the anatomy of the squid nervous system revealed the existence of giant nerve fibers suitable for exploring the fundamental mechanisms of nerve function. Geren and Schmitt (2) made the first electron microscopic observations of these fibers. Our work has been concerned with the study of the functional organization of these giant(More)