apparatuses of the present invention the materials used to form the core and sheath portions of the fibers formed in the present invention are placed into solution before being introduced into the apparatuses that are used for fiber formation the core polymer solution preferably has a viscosity of between 1 and 100 000 centipoise and is preferably pumped through the inner vessel 210 at rates of between 0 01 and 1000 milliliters per hour per centimeter more preferably between 5 and 200 milliliters per hour per centimeter a voltage preferably between 1 and 250 kv more preferably between 20 100 kv is applied the positive electrode of the power supply is preferably connected to one or both of the vessels 210 270 such that a potential exists between one or both of the vessels and a grounded collector that is placed at a distance in alternate embodiments the collector is oppositely charged relative to the polymer solution s in some embodiments the collector 250 includes one or more grounded or oppositely charged points for example two grounded points separated by a space and fibers collect around the one or more points and or between them upon application of a sufficient voltage taylor cones 240 and electrospinning jets 241 will form at the exposed surface of core and or sheath polymer solution s 230 260 and the jets will attract towards the collector in preferred embodiments core and or sheath polymer solutions 230 260.