WE CLAIM:
1. A tubular structure comprising a tubular base and a cover which covers said
base, wherein
said cover comprises a copolymer containing a silicone monomer and a polymerizable monomer having a fluoroalkyl group(s) as monomer units.
2. The tubular structure of claim 1, wherein said silicone monomer is
represented by the following Formula (I):
wherein X1 and X2 independently represent a polymerizable functional group; R1 to R8 independently represent hydrogen or a functional group selected from the group consisting of C1-C20 alkyl groups, phenyl group, and C1-C20 fluoroalkyl groups; L1 and L2 independently represent a divalent group; and m and n independently represent an integer of 0 to 1500 with the proviso that m and n are not simultaneously 0.
3. The tubular structure of claim 2, wherein said X1 and X2 are (meth)acryloyl groups.
4. The tubular structure of any one of claims 1 to 3, wherein said polymerizable monomer having a fluoroalkyl group(s) is represented by the following Formula (II):
wherein R9 represents hydrogen or a methyl group; and R10 represents a C1-C20 fluoroalkyl group.
5. The tubular structure of any one of claims 1 to 4, which satisfies the
following Expression 1:

iVl2 < 5.0 ••• Expression 1 wherein I1 represents an absorbance in the range of from 1740 to 1780 cm"1 due to stretching vibration of C=0 originated from ester groups; and I2 represents an absorbance in the range of from 1430 to 1470 cm"1 due to bending vibration of C-H originated from alkyl groups,
when the surface of said cover is subjected to a measurement by single-reflection infrared spectroscopy at a wavelength of 2.5 to 25 \xm and an angle of incidence of 45°.
6. The tubular structure of any one of claims 1 to 5, wherein said copolymer has a carboxyl group(s) and/or a hydroxy 1 group(s).
7. The tubular structure of claim 5 or 6, wherein said copolymer comprises a structure represented by the following Formula (III):
wherein R9 represents hydrogen or a methyl group, and L3 represents a monovalent group.
8. The tubular structure of any one of claims 1 to 7, wherein said base is composed of a polyester, polyurethane, or polytetrafluoroethylene.
9. The tubular structure of any one of claims 1 to 8, wherein said tubular base is a tubular woven fabric comprising warp yarns and weft yarns, said tubular structure having an outer diameter with a variation of within 10% along the warp direction and satisfying the following Expression 2:
wherein LI is a gauge length of the tubular woven fabric when compressed in the warp direction by applying a stress of 0.01 cN/dtex, as determined after the outer diameter of the tubular woven fabric is measured without applying stress to the

tubular woven fabric to determine a maximum outer diameter and then gauge marks are drawn around an outer circumference of the tubular woven fabric so that the gauge marks are separated by a length of five times the maximum outer diameter of the tubular woven fabric; and L2 is a guage length when elongated in the warp direction by applying a stress of 0.01 cN/dtex.
10. The tubular structure of any one of claims 1 to 9, wherein said tubular base is
a tubular woven fabric comprising warp yarns and weft yarns, wherein said tubular
woven fabric satisfies the following Expression 3:
0.03 < (a - b)/a < 0.2 ••• Expression 3 wherein "a" is a maximum outer diameter of the tubular woven fabric when compressed in the warp direction by applying a stress of 0.01 cN/dtex, and "b" is a minimum outer diameter of the tubular woven fabric when elongated in the warp direction by applying a stress of 0.01 cN/dtex.
11. The tubular structure of any one of claims 1 to 10, which is a medical tube implantable in the body.
12. The tubular structure of any one of claims 1 to 10, which is an artificial blood vessel.