Abstract:
An implantable tissue expander including an internal skeletal element extending between a base surface and an outer surface and including at least one plurality of elongate cells extending along mutually generally parallel axes from the base surface to the outer surface and being defined by elongate cell walls formed of a resilient material and a sealed enclosure, sealing the internal skeletal element and adapted for preventing body fluids from filling the plurality of elongate cells.

Description:
REFERENCE TO RELATED APPLICATIONS 
     Reference is made to U.S. Provisional Patent Application Ser. No. 60/878,564, filed Jan. 3, 2007 and entitled “Human Implantable Tissue Expander,” the disclosure of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i). 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to implantable tissue expanders generally. 
     BACKGROUND OF THE INVENTION 
     The following published patent documents are believed to represent the current state of the art: 
     U.S. Pat. Nos. 6,315,796 and 6,605,116, and 
     U.S. Published Patent Application Nos. 2001/0010024; 2003/0074084 and 2004/0148024. 
     SUMMARY OF THE INVENTION 
     The present invention relates to implantable tissue expanders. 
     There is thus provided in accordance with a preferred embodiment of the present invention an implantable tissue expander including an integrally formed internal skeletal element extending between a base surface and an outer surface and including at least one plurality of elongate cells extending along mutually generally parallel axes from the base surface to the outer surface and being mutually defined by elongate cell walls formed of a resilient material and a sealed enclosure, sealing the internal skeletal element and adapted for preventing body fluids from filling the plurality of elongate cells. 
     Preferably, the at least one plurality of elongate cells includes at least first and second pluralities of elongate cells extending over correspondingly different mutually generally parallel axes from the base surface to the outer surface. Alternatively, the at least one plurality of elongate cells includes a single plurality of elongate cells extending over mutually generally parallel axes from the base surface to the outer surface. 
     Preferably, the base surface is generally flat. Additionally or alternatively; the outer surface is generally convex. 
     Preferably, the elongate cell walls define fluid passageways communicating between adjacent cells in the at least one plurality of elongate cells. Additionally or alternatively, the at least one plurality of elongate cells includes a central cylindrical cell. 
     Preferably, the elongate cell walls are of generally uniform thickness. Additionally or alternatively, the at least one plurality of elongate cells includes partial cells located along the periphery thereof. Preferably, the partial cells are identical. Preferably, the elongate cells have a hexagonal cross section. 
     Preferably, the implantable tissue expander includes at least one mesh. Additionally, the at least one mesh is formed of a highly deformable, minimally stretchable material. Additionally or alternatively, the at least one mesh is at least partially integrated with the sealed enclosure. 
     Preferably, the at least one mesh includes a plurality of layers of mesh. Additionally, at least two layers of mesh are located on opposite sides of at least one layer of the sealed enclosure. 
     Preferably, the sealed enclosure includes a generally convex portion and a base portion. Additionally or alternatively, the sealed enclosure includes multiple enclosure layers. 
     Preferably, the implantable tissue expander also includes a tube communicating with the interior of the sealed enclosure. Additionally or alternatively, the sealed enclosure has non-uniform wall thickness. 
     There is also provided in accordance with another preferred embodiment of the present invention a method of manufacturing an implantable tissue expander including forming an internal skeletal element, the internal skeletal element extending between a base surface and an outer surface and including at least one plurality of elongate cells extending along mutually generally parallel axes from the base surface to the outer surface and being defined by elongate cell walls formed of a resilient material and forming a peripheral enclosure over the internal skeletal element, the peripheral enclosure being operative to seal the internal skeletal element and being adapted to prevent body fluids from filling the plurality of elongate cells. 
     Preferably, the forming a peripheral enclosure includes forming a base portion of the enclosure and a generally convex portion of the enclosure and polymerizing the base portion together with the periphery of the generally convex portion and with edges of the elongate cell walls. 
     Preferably, the method also includes forming an outer enclosure over the peripheral enclosure. Additionally or alternatively, the forming steps include integrally forming the internal skeletal element and a generally convex portion of the peripheral enclosure over a mesh. 
     Preferably, the method also includes providing a tube communicating with the interior of the peripheral enclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
         FIGS. 1A ,  1 B,  1 C and  1 D are, respectively, pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element employed in an implantable tissue expander in accordance with a preferred embodiment of the present invention; 
         FIGS. 2A ,  2 B,  2 C and  2 D are, respectively, pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element employed in an implantable tissue expander in accordance with another preferred embodiment of the present invention; 
         FIGS. 3A ,  3 B,  3 C and  3 D are, respectively, pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element employed in an implantable tissue expander in accordance with yet another preferred embodiment of the present invention; 
         FIG. 4  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with one embodiment of the present invention; 
         FIG. 5  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with another embodiment of the present invention; 
         FIG. 6  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with yet another embodiment of the present invention; 
         FIG. 7  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with yet another embodiment of the present invention; 
         FIG. 8  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with still another embodiment of the present invention; 
         FIG. 9  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with yet another embodiment of the present invention; 
         FIG. 10  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with still another embodiment of the present invention; 
         FIG. 11  is a sectional illustration of an implantable tissue expander employing an internal skeletal element and constructed and operative in accordance with yet another embodiment of the present invention; 
         FIG. 12  is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 4  in accordance with an embodiment of the invention; 
         FIGS. 13A and 13B  together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 5  in accordance with another embodiment of the present invention; 
         FIGS. 14A and 14B  together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 6  in accordance with yet another embodiment of the present invention; 
         FIGS. 15A and 15B  together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 7  in accordance with still another embodiment of the present invention; 
         FIG. 16  is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 8  in accordance with a further embodiment of the present invention; 
         FIG. 17  is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 9  in accordance with a still further embodiment of the present invention; 
         FIG. 18  is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 10  in accordance with yet a further embodiment of the present invention; and 
         FIG. 19  is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 11  in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference is now made to  FIGS. 1A ,  1 B,  1 C and  1 D, which are, respectively, pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element  100  employed in an implantable tissue expander in accordance with a preferred embodiment of the present invention. 
     As seen in  FIGS. 1A-1D , the integrally formed internal skeletal element  100  includes an array of elongate cells  102  extending along mutually generally parallel axes  104  from an imaginary base surface  106 , which is typically flat, as in the illustrated embodiment, to an imaginary outer surface  108 , which is preferably generally convex and is tucked in adjacent the imaginary base surface  106  as seen clearly in  FIGS. 1A-1C . Elongate cells  102  are mutually defined by elongate cell walls  110  formed of a resilient material. Elongate cell walls  110  are preferably formed so as to define fluid passageways  111  communicating between adjacent cells  102 . The internal skeletal element  100  is capable of independently exhibiting a defined, convex, three-dimensional shape. 
     In the illustrated embodiment, the array of elongate cells  102  is preferably characterized in that it includes a central cylindrical cell  112  and that elongate cell walls  110  are of generally uniform thickness. It is also characterized in that a regular pattern of partial cells  114  are located along the periphery of the array. In the illustrated embodiment of  FIGS. 1A-1D , all of the partial cells  114  are identical. In other embodiments, this is not necessarily the case. Alternatively, the elongate well walls  110  need not be of generally uniform thickness and may be of different thicknesses and/or varying thickness. 
     Reference is now made to  FIGS. 2A ,  2 B,  2 C and  2 D, which are respectively pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element  200  employed in an implantable tissue expander in accordance with a preferred embodiment of the present invention. 
     As seen in  FIGS. 2A-2D , the integrally formed internal skeletal element  200  includes an array of elongate cells including a first plurality of elongate cells  202  at the center of the array, which cells  202  extend along mutually generally parallel axes  204  and a second plurality of elongate cells  206 , each of which extends along an axis  208  which is splayed outwardly with respect to axes  204 . Cells  202  and  206  extend from an imaginary base surface  210 , which is typically flat, as in the illustrated embodiment, to an imaginary outer surface  212 , which is preferably generally convex and is tucked in adjacent the imaginary base surface  210  as seen in  FIGS. 2A-2D . Elongate cells  202  and  206  are mutually defined by elongate cell walls  214  formed of a resilient material. Elongate cell walls  214  are preferably formed so as to define fluid passageways  215  communicating between adjacent cells  202  and  206 . 
     In the illustrated embodiment, the array of elongate cells  202  is preferably characterized in that it includes a central cylindrical cell  216  and that elongate cell walls  214  are of generally uniform thickness. It is also characterized in that a regular pattern of partial cells  218  are located along the periphery of the array. In the illustrated embodiment of  FIGS. 2A-2D , all of the partial cells  218  are identical. In other embodiments, this is not necessarily the case. 
     Reference is now made to  FIGS. 3A ,  3 B,  3 C and  3 D, which are respectively pictorial top view, pictorial bottom view, first sectional and second sectional illustrations of an integrally formed internal skeletal element  300  employed in an implantable tissue expander in accordance with a preferred embodiment of the present invention. 
     As seen in  FIGS. 3A-3D , the integrally formed internal skeletal element  300  includes an array of identical elongate cells  302 , each having an hexagonal cross section, extending along mutually generally parallel axes  304  from an imaginary base surface  306 , which is typically flat, as in the illustrated embodiment, to an imaginary outer surface  308 , which is preferably generally convex and is tucked in adjacent the imaginary base surface  306  as seen clearly in  FIGS. 3A-3C . Elongate cells  302  are mutually defined by elongate cell walls  310  formed of a resilient material. Elongate cell walls  310  are preferably formed so as to define fluid passageways  311  communicating between adjacent cells  302 . 
     In the illustrated embodiment, the array of elongate cells  302  is preferably characterized in that elongate cell walls  310  are of generally uniform thickness. It is also characterized in that a regular pattern of partial cells  312  are located along the periphery of the array. In the illustrated embodiment of  FIGS. 3A-3D , the partial cells  312  are not identical. 
     Reference is now made to  FIG. 4 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with a preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . As seen in  FIG. 4 , the internal skeletal element  100  is enclosed by a peripheral enclosure  400 , which preferably includes a generally convex portion  402  which is co-molded with internal skeletal element  100  and a base portion  404  which is polymerized together with the periphery of the convex portion  402  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. 
     The internal skeletal element  100  and the peripheral enclosure  400  are enclosed by an outer peripheral enclosure  406 , which preferably includes a generally convex portion  408  integrally formed with a base portion  410  which are together molded as one piece over peripheral enclosure  400 . 
     Preferably, a tube  412  communicates with the interior of peripheral enclosure  400 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  400  at ambient pressure. 
     It is appreciated that the enclosures employed in various embodiments of the present invention, such as, for example enclosure  400 , may be of any suitable thickness. Such thickness may be uniform or varied. 
     Reference is now made to  FIG. 5 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with another preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 5 , a mesh  500 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100 . 
     As seen in  FIG. 5 , the internal skeletal element  100  and the mesh  500  are enclosed by a peripheral enclosure  502 , which preferably includes a generally convex portion  504  which is co-molded with internal skeletal element  100  over mesh  500 . Peripheral enclosure  502  also includes a base portion  506  which is polymerized together with the periphery of the convex portion  504  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. 
     The internal skeletal element  100  and the mesh  500  are enclosed by an outer peripheral enclosure  508 , which preferably includes a generally convex portion  510  integrally formed with a base portion  512  which are together molded as one piece over peripheral enclosure  502  and mesh  500 . 
     Preferably, a tube  514  communicates with the interior of peripheral enclosure  502 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  502  at ambient pressure. 
     Reference is now made to  FIG. 6 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with yet another preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 6 , a mesh  600 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100  and a peripheral enclosure  602 . 
     As seen in  FIG. 6 , the internal skeletal element  100  is enclosed by peripheral enclosure  602 , which preferably includes a generally convex portion  604  which is co-molded with internal skeletal element  100  and a base portion  606  which is polymerized together with the periphery of the convex portion  604  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. 
     The internal skeletal element  100  and the mesh  600  are enclosed by an outer peripheral enclosure  608 , which preferably includes a generally convex portion  610  integrally formed with a base portion  612  which are together molded as one piece over peripheral enclosure  602  and mesh  600 . 
     Preferably, a tube  614  communicates with the interior of peripheral enclosure  602 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  602  at ambient pressure. 
     Reference is now made to  FIG. 7 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with still another preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 7 , a mesh  700 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100  and first and second peripheral enclosures  702  and  704 . Mesh  700  may be entirely external of enclosure  704  and may or may not be attached thereto. Alternatively mesh  700  may be wholly or partially integrated within peripheral enclosure  704 . 
     As seen in  FIG. 7 , the internal skeletal element  100  is enclosed by first peripheral enclosure  702 , which preferably includes a generally convex portion  706  which is co-molded with internal skeletal element  100  and a base portion  708  which is polymerized together with the periphery of the convex portion  706  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. First peripheral enclosure  702  is preferably enclosed by second, outer peripheral enclosure  704 , which preferably includes generally convex portion  710  integrally formed with base portion  712  which are together molded as one piece over first peripheral enclosure  702 . 
     Preferably, a tube  714  communicates with the interior of peripheral enclosure  702 . The tube is preferably sealed after implantation so as to maintain the interior of first peripheral enclosure  702  at ambient pressure. 
     Reference is now made to  FIG. 8 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with yet another preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 8 , a mesh  800 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100  and a generally convex portion  802 . 
     As seen in  FIG. 8 , the internal skeletal element  100  is partially enclosed by generally convex portion  802 , which is co-molded with internal skeletal element  100 . The internal skeletal element  100  and the generally convex portion  802  are fully enclosed by mesh  800 . A base portion  806  is polymerized together with the periphery of the convex portion  802  and with the edges of elongate cell walls  110  over mesh  800  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive, thereby defining a first peripheral enclosure  807 . 
     First peripheral enclosure  807  is preferably enclosed by a second, outer peripheral enclosure  808 , which preferably includes a generally convex portion  810  integrally formed with a base portion  812  which are together molded as one piece over first peripheral enclosure  807 . It is appreciated that attachment of base portion  806  to convex portion  802  may occur prior to or in the same molding process as that which produces the second peripheral enclosure  808 . As a third alternative, either base portion  806  or base portion  812  may be obviated. 
     Preferably, a tube  814  communicates with the interior of first peripheral enclosure  804 . The tube is preferably sealed after implantation so as to maintain the interior of the first peripheral enclosure  804  at ambient pressure. 
     Reference is now made to  FIG. 9 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with still another preferred, embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 9 , a first mesh  900 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100 . The term “mesh” is used in a broad sense to cover any type of open enclosure, such as a fabric enclosure, which may be woven or non-woven and may have regular or irregularly shaped and spaced openings. A mesh may be formed of a single piece or multiple pieces or strands of material in any suitable manner, such as for example, by injection molding, winding or wrapping. 
     As seen in  FIG. 9 , the internal skeletal element  100  and first mesh  900  are enclosed by a peripheral enclosure  902 , which preferably includes a generally convex portion  904  which is co-molded with internal skeletal element  100  over first mesh  900 . Peripheral enclosure  902  also includes a base portion  906  which is polymerized together with the periphery of the convex portion  904  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. 
     The internal skeletal element  100  and first mesh  900  are enclosed by an outer peripheral enclosure  908 , which preferably includes a generally convex portion  910  integrally formed with a base portion  912  which are together molded as one piece over peripheral enclosure  902  and first mesh  900 . 
     A second mesh  914  is preferably formed or wrapped around the outer peripheral enclosure  908 . Preferably, a tube  916  communicates with the interior of peripheral enclosure  902 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  902  at ambient pressure. 
     Reference is now made to  FIG. 10 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with yet a further preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 10 , a first mesh  1000 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100  and a peripheral enclosure  1002 . 
     As seen in  FIG. 10 , the internal skeletal element  100  is enclosed by peripheral enclosure  1002 , which preferably includes a generally convex portion  1004  which is co-molded with internal skeletal element  100  and a base portion  1006  which is polymerized together with the periphery of the convex portion  1004  and with the edges of elongate cell walls  110  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive. 
     The internal skeletal element  100  and the first mesh  1000  are enclosed by an outer peripheral enclosure  1008 , which preferably includes a generally convex portion  1010  integrally formed with a base portion  1012  which are together molded as one piece over peripheral enclosure  1002  and mesh  1000 . 
     A second mesh  1014  is preferably formed or wrapped around the outer peripheral enclosure  1008 . Preferably, a tube  1016  communicates with the interior of peripheral enclosure  1002 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  1002  at ambient pressure. 
     Reference is now made to  FIG. 11 , which is a sectional illustration of an implantable tissue expander constructed and operative in accordance with still another preferred embodiment of the present invention and employing the internal skeletal element  100  of  FIGS. 1A-1D . In the embodiment of  FIG. 11 , a first mesh  1100 , preferably formed of highly deformable but minimally stretchable materials, such as polyethylene or polyurethane, surrounds internal skeletal element  100  and a generally convex portion  1102 . 
     As seen in  FIG. 11 , the internal skeletal element  100  is partially enclosed by generally convex portion  1102 , which is co-molded with internal skeletal element  100 . The internal skeletal element  100  and the generally convex portion  1102  are fully enclosed by first mesh  1100 . A base portion  1106  is polymerized together with the periphery of the convex portion  1102  and with the edges of elongate cell walls  110  over mesh  1100  at imaginary base surface  106  or alternatively sealingly joined thereto by use of a suitable adhesive, thereby defining a first peripheral enclosure  1107 . 
     First peripheral enclosure  1107  is preferably enclosed by a second, outer peripheral enclosure  1108 , which preferably includes a generally convex portion  1110  integrally formed with a base portion  1112  which are together molded as one piece over first peripheral enclosure  1107 . It is appreciated that attachment of base portion  1106  to convex portion  1102  may occur prior to or in the same molding process as that which produces the second peripheral enclosure  1108 . As a third alternative, either base portion  1106  or base portion  1112  may be obviated. 
     A second mesh  1114  is preferably formed or wrapped around the outer peripheral enclosure  1108 . Preferably, a tube  1116  communicates with the interior of peripheral enclosure  1102 . The tube is preferably sealed after implantation so as to maintain the interior of the peripheral enclosure  1102  at ambient pressure. 
     Reference is now made to  FIG. 12 , which is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 4 . As seen in  FIG. 12 , the internal skeletal element  100  and the generally convex portion  402  of peripheral enclosure  400  are co-molded as one piece as seen at stages designated A, B and C. Thereafter, in a subsequent separate molding stage, designated D, base portion  404  is formed and polymerized together with the periphery of the convex portion  402  and with the edges of elongate cell walls  110  at imaginary base surface  106 . Thereafter, in a subsequent separate molding stage designated E, outer peripheral enclosure  406  is formed over peripheral enclosure  404 . Tube  412  (not shown) may also be formed in molding stage E. 
     Reference is now made to  FIGS. 13A &amp; 13B , which together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 5 . As seen in  FIGS. 13A &amp; 13B , the internal skeletal element  100  and the generally convex portion  504  of peripheral enclosure  502  are co-molded as one piece over mesh  500  as seen at stages designated A, B and C. Thereafter, the mesh  500  is fitted over the internal skeletal element  100  at the imaginary base surface  106  and fixed in position, preferably without folding of the mesh, as shown at stage D. In a subsequent separate molding stage, designated E, base portion  506  is formed and polymerized together with the periphery of the convex portion  504  and with the edges of elongate cell walls  110  at imaginary base surface  106 . Tube  514  (not shown) may also be formed in molding stage E. 
     In a subsequent separate molding stage, designated G, the outer peripheral enclosure  508  is molded as one piece over inner peripheral enclosure  502 . 
     Reference is now made to  FIGS. 14A &amp; 14B , which together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 6 . As seen in  FIGS. 14A &amp; 14B , the internal skeletal element  100  and the generally convex portion  604  of peripheral enclosure  602  are co-molded as one piece as seen at stages designated A, B and C. Thereafter, in a subsequent separate molding stage, designated D, base portion  606  is formed and polymerized together with the periphery of the convex portion  604  and with the edges of elongate cell walls  110  at imaginary base surface  106 . Tube  614  (not shown) may also be formed in molding stage D. 
     Thereafter, mesh  600  is fitted over the internal skeletal element  100  at the imaginary base surface  106  and fixed in position, preferably without folding of the mesh, as shown at stage F. In a subsequent separate molding stage, designated H, the outer peripheral enclosure  608  is molded as one piece over peripheral enclosure  602  and mesh  600 . 
     Reference is now made to  FIGS. 15A &amp; 15B , which together are a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 7 . As seen in  FIGS. 15A &amp; 15B , the internal skeletal element  100  and the generally convex portion  706  of first peripheral enclosure  702  are co-molded as one piece as seen at stages designated A, B and C. Thereafter, in a subsequent separate molding stage, designated D, base portion  708  is formed and polymerized together with the periphery of the convex portion  706  and with the edges of elongate cell walls  110  at imaginary base surface  106 . Tube  714  (not shown) may also be formed in molding stage D. 
     In a subsequent separate molding stage, designated E, the outer peripheral enclosure  704  is molded as one piece over first peripheral enclosure  702 . 
     Thereafter, the mesh  700  is fitted over the outer peripheral enclosure  708  and fixed in position, preferably without folding of mesh  700  as shown at stage G. 
     Reference is now made to  FIG. 16 , which is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 8  in accordance with another embodiment of the present invention. Internal skeletal element  100  is integrally formed with generally convex portion  802  forming part of first peripheral enclosure  807 , in a manner which may be identical to the formation of internal skeletal element  100  and the generally convex portion  402  of peripheral enclosure  400  shown in  FIG. 12  at stages designated A, B and C and described hereinabove. 
     As shown at a stage designated B, the integrally formed internal skeletal element  100  and generally convex portion  802  are then temporarily and resiliently deformed to fit within mesh  800 , here shaped generally to conform to the outer surface of convex portion  802 . The mesh  800  surrounds the integrally formed internal skeletal element  100  and generally convex portion  802  and is retained in position with respect thereto. The mesh  800  is fitted over the internal skeletal element  100  at the imaginary base surface  106  and fixed in position, preferably without folding of mesh  800 , as shown at stage C. 
     Thereafter, in a subsequent separate molding stage, designated D, outer peripheral enclosure  808  is formed over first peripheral enclosure  807 . Tube  814  (not shown) may also be formed in molding stage D. 
     It is appreciated that attachment of base portion  806  to convex portion  802  may occur prior to or in the same molding process as that which produces the second peripheral enclosure  808 . As a third alternative, either base portion  806  or base portion  812  may be obviated. 
     Reference is now made to  FIG. 17 , which is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 9  in accordance with another embodiment of the present invention. Internal skeletal element  100  is formed with first mesh  900 , peripheral enclosure  902  and outer peripheral enclosure  908  in a manner which may be identical to the formation of internal skeletal element  100  and peripheral enclosures  502  and  508  as shown in  FIGS. 13A and 13B  at stages designated A-H and described hereinabove. 
     As shown at a stage designated B, the internal skeletal element  100 , first mesh  900  and peripheral enclosures  902  and  908  are then temporarily and resiliently deformed to fit within second mesh  914 , here shaped generally to conform to the outer surface of outer peripheral enclosure  908 . Second mesh  914  surrounds the integrally formed internal skeletal element  100  and outer peripheral enclosure  908  and is retained in position with respect thereto. 
     Reference is now made to  FIG. 18 , which is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 10 . Following the methodology of stages A-H of  FIGS. 14A &amp; 14B , described hereinabove, second mesh  1014  is preferably formed or wrapped around the outer peripheral enclosure  1008 , preferably without folding of the mesh. 
     Reference is now made to  FIG. 19 , which is a simplified illustration of a method of manufacturing the implantable tissue expander of  FIG. 11 . Following the methodology of stages A-E of  FIG. 16 , described hereinabove, second mesh  1114  is preferably formed or wrapped around the outer peripheral enclosure  1108 , preferably without folding of second mesh  1114 . 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various feature described hereinabove as well as modifications and variations thereof which would occur to a person skilled in the art upon reading the foregoing description and which are not in the prior art.