Abstract:
The present invention seeks to provide an improved needle design and needle assembly which is particularly adapted for live cell vaccines and the like. More specifically, the needle assembly includes a gap filler with an inner funnel which is specifically shaped and adapted to fill a turbulence gap naturally formed between a conventional needle retainer and syringe. By maintaining a laminar flow of the fluid, the turbulence and the destruction of live cells are reduced. Additionally, some of the needle designs include a funnel-shaped mouth which is utilized during the filling of the syringe to minimize physical damage to the cell wall or membrane of the live cells otherwise caused by the sharp edges at the tip of a standard injection needle. A breakaway needle assembly is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to improved needle designs for live vaccines and, in particular, live vaccines for Marek&#39;s and other diseases affecting chicken and other avian species, as well as for live microorganisms in general. More specifically, the present invention relates to a pair of needle assemblies having a needle and needle retainer which minimizes turbulence and damage to the live cells during transfer of vaccine fluids into and out of a standard syringe.  
           [0003]    2. Prior Art  
           [0004]    Marek&#39;s disease is a viral disease of chickens resulting in a type of cancer, and is one of the most serious threats to poultry health. This virus lies latent in T-cells, which are a type of white blood cells. T-cells are an integral part of the immune system response which is the bird&#39;s natural defense against disease. Within three weeks of infection, the fatal virus manifests as aggressive tumors in the spleen, liver, kidney, gonads, skin and muscle of the infected bird.  
           [0005]    Marek&#39;s disease is a herpesvirus-induced lymphoprolifertive disease that occurs naturally in chickens. Since the advent of the turkey herpesvirus vaccine (HVT), newly hatched chicks have been routinely inoculated against the disease prior to being placed in the brooder houses. Although HVT vaccine is generally quite effective, occasionally inoculated flocks experience heavy Marek&#39;s disease losses. More recently, it has been found that by proper selection of both the site and time of inoculation, embryonic vaccination can be effective in the control of poultry diseases. It is essential that the egg be injected during the final quarter of the incubation period, and that the inoculate be injected within either of the regions defined by the amnion or the yolk sac. Under these conditions, the embryo will favorably respond immunologically to the vaccine with no significant impairment of its prenatal development.  
           [0006]    A live cell-associated virus vaccine of tissue culture origin typically contains the Rispens strain, the SB1 strain of the chicken herpes-virus and the FC 126 HVT strain of the turkey herpes virus alone or in combination. The vaccine is presented in glass ampules containing concentrated vaccine, typically 1000 doses each, with a specified titer defined as Plaque Forming Units (“PFUs”). The vaccine product is stored in a frozen condition typically in liquid nitrogen freezer and shipped in liquid nitrogen. A special sterile diluent is supplied in a separate package, typically a sealed plastic bag with appropriate injection port and delivery tube opening. The vaccine is reconstituted by thawing the frozen vaccine in the glass ampule. The ampule is then broken open and the liquid vaccine product is withdrawn from the ampule using a standard needle and syringe. The diluent is stored at room temperature until a few hours prior to use when the concentrated vaccine product withdrawn from the ampule by the needle and syringe is then injected into the diluent contained in the sealed plastic bag through the bag injection port. The reconstituted vaccine is then ready for delivery from the sealed bag through the delivery tube.  
           [0007]    There are various factors that affect the level of PFUs delivered by a live cell vaccine, such as Marek&#39;s vaccine, to an inoculated specimen. Most of these factors occur during the vaccine reconstitution and in the delivery process and both have to do with vaccine handling, temperature, turbulence in the syringe, air pressure, friction, pH, vaccine delivery tube, length and diameter, needle length and diameter, needle shape and delay in vaccine consumption after thawing. Elimination or reduction of the adverse effects arising from any one of these noted factors would greatly improve the inoculation process for Marek&#39;s vaccine, specifically, and for live cell vaccines, generally.  
           [0008]    A conventional needle configuration for drawing a vaccine fluid into a syringe and subsequently delivering the vaccine from the syringe to a vaccine delivery system, such as an automated injection system for avian embryos as disclosed in U.S. Pat. No. 4,681,063, is illustrated in FIG. 1. As shown, a conventional syringe needle, generally designated by reference numeral  110 , is attached to a conventional syringe, generally designated by reference numeral  112 . The syringe  112  has a hollow tubular barrel  114  having a chamber  116  for retaining fluid, such as the live vaccine. The syringe  112  also has a plunger with a flexible plug (not shown). As is common in the art, the plug will sealingly engage against an inner surface  118  of the syringe barrel  114 , with the plunger being pulled out of the chamber  116  to draw fluid into the chamber and being pushed into the chamber  116  to inject fluid out of the chamber.  
           [0009]    The syringe  112  has a standard tubular extension  120  projecting from end  122  of the barrel  114 . The tubular extension  120  has a cylindrical axial passageway  126  which communicates with the syringe chamber  116  and needle assembly  110 , when attached. The tubular extension  120  is surrounded by a collar  124  which has internal male threads  125  so that the needle assembly  110  can be sealingly attached in a conventional manner by outwardly extending flange  138  screwing downwardly on threads  125 .  
           [0010]    The needle assembly  110  includes an injection needle  133  and a needle retainer  128 . The retainer  128  is mounted on the forward end of the syringe  112  as previously described to retain the needle assembly  110  in generally axial alignment with the syringe  112  and tubular extension  120 . The needle  133  is made of conventional needle materials, such as stainless steel for strength and chemical compatibility, and the retainer  128  is preferably made of a suitable plastic material which can be easily molded around the end  136  of needle  133 .  
           [0011]    The needle  133  includes a hollow central passageway  134  and a sharpened tip  130  at its outer end  132  formed by an angled cut of the hollow needle. The needle  133  is preferably surrounded by a cap or sheath (not shown) before the needle is used for sterility, and the sheath is easily removed in a conventional manner when the needle and syringe are ready for use.  
           [0012]    To hold the needle assembly  110  in generally axial alignment with the syringe, the retainer  128  has an axial bore  141  and an outwardly projecting rim or flange  138  at the syringe receiving end. The axial bore  141  is sized to fit in sealing engagement over the tubular extension  120 , while the outer circumference of the rim or flange  138  engages the threads  125  on the inner wall of surrounding collar  124 . As assembled, the outwardly projecting rim or flange  138  snugly fits down into space  139  between the outer surface of the tubular extension  120  and the inner surface of the collar  124 . Thus, mounted on the syringe  112 , the hollow central passageway  134  of the needle portion  133  aligns with the passageway  126  of the tubular extension  120  and the chamber  116  of the syringe  112 .  
           [0013]    The conventional syringe and needle assembly as previously described and shown in FIG. 1 is commonly used and well known. The assembly is particularly intended for single dosage use, and for storage, transportation, and injection while filled with fluid. It is also the standard assembly for transferring concentrated live virus vaccines, such as Marek&#39;s vaccine, from supply ampules to diluent storage containers or bags where it is appropriately diluted for delivery to a specimen to be vaccinated, such as chicken egg embryos and the like, by known vaccine delivery machines or systems. It has been surprisingly discovered that the use of this conventional syringe and needle assembly for transferring live vaccines creates unexpected problems in the destruction of the live cells caused by turbulence of the vaccine during both the drawing of the vaccine into the syringe chamber  116  and the discharge of the vaccine from the chamber  116 , through the passageway  126  of extension  120  and the passageway  134  of the needle  133 .  
           [0014]    While it was known that turbulence could be detrimental to the live cell count of various vaccines, including Marek&#39;s vaccine, it was not appreciated that the conventional syringe and needle assembly as commonly used for transfer of these vaccines would cause significant turbulence and that this turbulence could significantly reduce the live cell count, or the PFUs of the vaccine, including Marek&#39;s vaccine, both during the filling of the syringe barrel  114  and during injection of the vaccine out of the syringe.  
           [0015]    The problem with this commonly used needle and syringe assembly is that a tubular gap, indicated by numeral  140  in FIG. 1, is formed between the top of the tubular extension  120  and the rear part  136  of the needle  110 . It has been found that this tubular gap  140  causes turbulence in the fluid flowing between needle  133  and tubular extension  120 , both during the filling of the syringe barrel  114  and during the injection of the vaccine from the syringe.  
           [0016]    To understand the effect of turbulence in the context of the present invention, it is believed that a brief discussion of flowing fluid would be helpful. When fluid flows slowly and smoothly, the flow is called laminar. At fast velocities, however, the inertia of the fluid overcomes fluid frictional forces and turbulent flow results. When a fluid is flowing this way, it flows in eddies and whorls (vortices), and there is much more drag than when the flow is laminar.  
           [0017]    Turbulence is composed of eddies: patches of zigzagging, often swirling fluid, moving randomly around and about the overall direction of motion. Technically, the chaotic state of fluid motion arises when the speed of the fluid exceeds a specific threshold, below which viscous forces damp out the chaotic behavior. As applied to live cell vaccines, such as Marek&#39;s vaccine, turbulence that disrupts the flow causes the live cells to bounce off one and another. This bouncing during the turbulence kills live cells, thus reducing the PFUs which can be delivered by the vaccine.  
           [0018]    Upon studying the conventional syringe and needle assembly, it has also been determined that damage to the live cells of the concentrated vaccine also occurs at the outer end  132  of the needle  133  due to the sharpened tip  130  during the drawing of the vaccine into the syringe barrel  114 . The live cells of known vaccines for inoculating chicken and other avian species embryos, including Marek&#39;s vaccine, as well as the live cells in many other live cell fluids are very fragile. Damage to the outer membrane or cell wall can cause rapid destruction of the live cell. It has been found that the sharp edges of the needle tip tend to physically damage the cell wall or membrane of the live cells when drawn into the needle. This damage can be very detrimental to the live cells in known vaccines, particularly Marek&#39;s vaccine, and substantially reduce the PFUs which can be delivered.  
         SUMMARY OF THE INVENTION  
         [0019]    In view of the turbulence generated by conventional needle designs and the sharp needle tip, as well as other problems and disadvantages of the prior art, the present invention seeks to provide improved needle designs and needle assemblies which are particularly adapted for transferring concentrated live cell vaccines and other fluids containing live cells. More specifically, the needle assemblies of the present invention are specifically shaped and adapted to fill the tubular gap between the needle retainer and the syringe to reduce the turbulence and destruction of the live cells of the vaccine, thus delivering higher PFU values. Additionally, the present invention includes a needle design which is utilized during the filling of the syringe to minimize the physical damage to the live cells of vaccines and other fluids caused by the sharp edges at the tip of the needle.  
           [0020]    In order to minimize the turbulence and promote a laminar flow of the concentrated vaccine, and to minimize physical damage to the live cells, the needle assemblies of the present invention modify the standard needle structure in two important ways.  
           [0021]    First, the needle retainer  128  is modified to include an insert or filler to fill the gap  140  while at the same time providing an axial passageway to connect passageway  126  of the syringe tubular extension  120  with the entrance to the passageway  134  of the needle  133 . The axial passageway of the gap insert or filler is designed to provide a smooth flow transition between the larger diameter extension passageway  126  and the smaller diameter needle passageway  134 . The insert or filler is sized so that the end facing the outer surface  145  of the extension  120  sealingly abuts the surface  145  when the needle retainer  128  is screw threaded into collar  124  and the axial bore  141  reaches tight sealing engagement around syringe extension  120 . In order that the fluid can have a continuous laminar flow, the gap insert or filler has an inner throughbore which is preferably funnel or conically shaped. The top opening of the throughbore is substantially equal in diameter to the rear opening of the needle, and the rear opening of the throughbore is substantially equal in diameter to the opening of the syringe extension passageway. Thus, the live cells are not bouncing around in the gap  140  and turbulence is minimized.  
           [0022]    Second, a different needle tip is used for drawing the concentrated vaccine from the ampule, in particular, a needle tip having a funnel shape to form an open mouth at the entrance end of the needle  133 . With this funnel shape, the needle end can more gently draw the vaccine into the hollow needle passageway  134  without damage to the cell wall caused by the sharp edges of pointed tip  130 . Since damage to the cell wall is minimized, the destruction of the live cells is reduced and each dosage of vaccine has higher PFUs to vaccinate the embryos.  
           [0023]    A needle with an open mouth in accordance with the present invention can be used when drawing the concentrated vaccine up from the ampule because the ampule has an opening for withdrawing the vaccine therefrom and does not need to be punctured by a sharp needle tip. On the other hand, when delivering the concentrated vaccine to a delivery system, it is typically desirable to puncture the container containing the vaccine diluent, through the injection port, or the container for holding the diluted vaccine for delivery to the avian embryos. In such circumstances, the needle tip must have a sharpened point such as used in the standard needle configuration. However, when delivering the concentrated vaccine from the syringe through the needle portion, the vaccine does not encounter the sharp edges at the needle tip, in contrast to drawing the concentrated vaccine into the needle. Hence, the standard needle tip does not cause significant disadvantages during the delivery of the concentrated vaccine into the diluent bag or other container.  
           [0024]    In one embodiment of the present invention the needle retainer is modified with the requisite insert or filler to provide a smooth laminar flow between the needle and the syringe. The needle also has a funnel shape to form an open mouth at its tip. The needle is further modified, however, to have a breakaway tip so that after the concentrated vaccine has been drawn into the syringe through the open mouth, the outer extremity of the needle can be broken away to leave a sharp point needle tip for subsequently injecting the concentrated vaccine into the diluent bag or other container. The breakaway tip is formed by a diagonally-positioned weakened area in the needle near the tip. The weakened area can be molded into the needle, if the needle is made from plastic, or scored or ground into the needle outer surface if the needle is made from metal.  
           [0025]    It is therefore an object of the present invention to provide a needle assembly which can be assembled on a conventional syringe and which minimizes the turbulence imparted to a concentrated vaccine, especially a vaccine containing live cells, so as to avoid destruction of the live cells during transfer of the vaccine using the needle and syringe assembly.  
           [0026]    Another object of the present invention is to provide a needle assembly in accordance with the preceding object and which includes a needle retainer having a tubular insert or filler with an inner funnel or conical shaped throughbore such that the opening adjacent the rear of the needle has a diameter substantially equal to the needle diameter and the opening adjacent the syringe extension has a diameter substantially equal to the diameter of the extension passageway.  
           [0027]    A further object of the present invention is to provide a needle assembly for attachment to a conventional syringe which has a needle tip that serves to reduce the physical damage imparted to the live cells contained in a concentrated vaccine or other fluid during the drawing of the vaccine into the syringe.  
           [0028]    A still further object of the present invention is to provide a needle assembly in accordance with the preceding object in which the needle tip has an open mouth with the mouth diameter larger than the diameter of the needle passageway.  
           [0029]    Still another object of the present invention is to provide a needle assembly in accordance with the preceding objects which has a needle tip that serves to reduce the physical damage imparted to the live cells contained in a concentrated vaccine or other fluid during the drawing of the vaccine into the syringe and has a breakaway needle configuration which, upon removal of the needle end, leaves a sharpened needle tip of standard configuration.  
           [0030]    A final object of the present invention to be set forth herein is to provide needle assemblies which can be installed on a conventional syringe and which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide needle assemblies that are economically feasible, highly strong and durable, and relatively trouble-free in use.  
           [0031]    These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 is a partial cut away side view illustrating a conventional needle assembly installed on the end of a conventional syringe;  
         [0033]    [0033]FIG. 2 is a partial cut away side view illustrating a needle assembly in accordance with the present invention installed on the end of a conventional syringe for transferring live cell vaccines and other fluids, and including a modified needle tip to have an open mouth;  
         [0034]    [0034]FIG. 3 is an enlarged cut away side view of FIG. 2 illustrating one embodiment of the open mouth needle tip of the present invention;  
         [0035]    [0035]FIG. 4 is another enlarged cut away side view of FIG. 2 illustrating another embodiment of the open mouth needle tip of the present invention;  
         [0036]    [0036]FIG. 5 is another enlarged cutaway side view illustrating a further embodiment of an open mouth needle tip of the present invention;  
         [0037]    [0037]FIG. 6 is a partial cutaway side view illustrating a needle assembly of the present invention installed on the end of a conventional syringe, except the needle tip is the standard piercing design; and  
         [0038]    [0038]FIG. 7 is a partial cutaway side view illustrating a further needle assembly in accordance with the present invention installed on the end of a conventional syringe for transferring live cell vaccines and other fluids, and including a breakaway needle tip. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    Although preferred embodiments of the present invention are explained in detail, it is to be understood that the embodiments are given by way of illustration only. It is not intended that the invention be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. Also, in describing the preferred embodiments, specific terminology will be resorted to for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.  
         [0040]    Referring now to FIG. 2, there is shown a needle assembly, generally designated by reference numeral  210 , assembled in a conventional manner on the end of a conventional syringe, generally designated by reference numeral  212 . The syringe  212  has a hollow tubular barrel  214  with a chamber  216  for receiving and retaining fluid. The needle assembly  210  is used in accordance with the present invention to draw fluid, especially live cell vaccines such as Marek&#39;s vaccine, into syringe barrel  214 . The syringe  212  also has a plunger with a flexible plug (not shown). As is common in the art, the plug will sealingly engage against inner surface  218  of the syringe barrel  214 , with the plunger being pulled out of the chamber  216  to draw fluid into the chamber  216  through the needle assembly  210 .  
         [0041]    The syringe  212  has a standard tubular extension  220  projecting from end  222  of the barrel  214 . The tubular extension  220  has a cylindrical axial passageway  226  which communicates with the syringe chamber  216  and needle assembly  210 , when attached. The tubular extension  220  is surrounded by a collar  224  which has internal male threads  225  so that the needle assembly  210  can be sealing attached in the conventional manner by outwardly extending flange  238  screwing downwardly on threads  225 .  
         [0042]    The needle assembly  210  includes a needle  233  and a needle retainer  228  at the attaching end for assembly on the forward portion of the syringe  212  in the conventional manner so that the needle  233  projects from the syringe  212 . The needle  233  is made of conventional needle materials, such as metal or plastic, and the needle retainer  228  is also made from conventional needle retainer materials, such as aluminum or plastic which can be readily molded onto the end of the needle  233 .  
         [0043]    The needle  233  includes a unique tip  230  at its forward end  232 , described below, and has a hollow center passageway  234 . When packaged, the needle  233  is preferably encased in a cap or sheath (not shown) for sterility, that is removably attached in a conventional manner to the exterior of the retainer assembly  228 . The needle retainer  228  includes a conventional outwardly projecting rim or flange  238  which is screw threaded downwardly inside the internal male threads  225  on the inside wall of collar  224  which surrounds the tubular extension  220  of syringe  212 . At the same time, the internal wall of the axial bore  241  at the attaching end of the needle retainer  228  engages the external surface of the syringe tubular extension  220  to form a tight seal therewith. When mounted on the syringe  212 , the center passageway  234  of the needle  233  aligns with the passageway  226  of extension  220  and the chamber  216  of the syringe.  
         [0044]    Reference is now directed to the needle tip  230  shown in FIG. 2 and, in more detail, in FIGS. 3 and 4. It has been found that when a conventional sharp tip needle is used to draw in live cell vaccines from their supply ampules, such as Marek&#39;s vaccine, into the chamber  216  of the syringe  212 , the sharp edges of the needle tip damage the wall or membrane of the cells, and a number of live cells are destroyed, thus reducing the PFUs level. To minimize this destruction of the live cells at the tip, an open mouth or funnel-shaped tip, generally designated by reference numeral  260 , has been developed.  
         [0045]    The funnel-shaped tip  260  is made of the same material as the remainder of the needle  233  and can be formed thereon in any conventional manner, such as by conventional mechanical and/or hydraulic equipment. The funnel-shaped tip  260  forms an open mouth  262 . In the embodiment shown in FIG. 3, the tip is angularly shaped to form the funnel-shaped mouth  262 . In the embodiment shown in FIG. 4, the funnel tip has a gradual curved shape to form the funnel-shaped mouth  262 .  
         [0046]    Turning next to the embodiment shown in FIG. 5, this embodiment differs somewhat from the needle tips shown in FIGS. 3 and 4. In the FIG. 5 embodiment, an enlarged tip  264  is attached at the end of needle  232 . The tip  264  is preferably made of the same material as the needle  232  and is molded onto the end of the needle  232 , if plastic, or welded on, if metal. The funnel shaped mouth  266  can then be formed in the open end of the enlarged tip  264  by a suitable machining or the like. With these funnel shapes in FIGS. 3, 4 and  5 , the needle can draw the live cell vaccine or other fluid and funnel it down into the needle passageway  234  with far less damage caused to the live cells at the needle tip. Hence, the destruction of live cells, and the reduction of PFUs in live cell vaccines, are substantially reduced.  
         [0047]    When drawing liquid into the syringe  212 , the plunger and flexible plug (not shown) move away from the end  222  of the barrel  214  thus pulling the liquid into the needle  210  and through the center passageway  234 . At this point, the fluid has a laminar flow. As the fluid reaches the rear part  236  of the needle  223 , it enters axial throughbore  252  of a tubular gap filler or insert  250 . The tubular gap filler or insert  250  fills the tubular gap  140  which otherwise would be present in conventional assemblies as described in accordance with FIG. 1. The throughbore  252  preferably provides an axial funnel or conical shaped passage.  
         [0048]    This funnel-shaped passage has an upper opening  254  which has substantially the same diameter as the hollow center passageway  234  of the needle  210 , and they are axially aligned. The throughbore  252  has a lower opening  256  which is much larger than the upper opening  254  and has substantially the same diameter as the syringe extension passageway  226  to which it is axially aligned, as well. Thus, as the fluid flows from the needle  210 , through the throughbore  252  of tubular gap filler  250  and into passageway  226 , the fluid remains substantially laminar as it continues to move into the chamber  216  of the syringe  212 . Since the tubular gap filler  250  maintains the fluid in a laminar flow, very few live cells are destroyed by turbulence if the fluid were a live cell vaccine, such as Marek&#39;s vaccine.  
         [0049]    The tubular gap filler or insert  250  is sized in the longitudinal direction so that the lower end sealingly engages the outer surface  245  of the syringe tubular extension  220  when the needle assembly  210  is properly assembled on the end of the syringe  212  as previously described. While the tubular gap filler or insert  250  is shown in FIG. 2 as a separate element inside the bore  241  of the needle retainer  228 , it is preferred that the gap filler  250  be molded as a unitary component together with the needle retainer  228  when the retainer  228  is molded onto the end  236  of the needle  233  while at the same time forming the funnel-shaped throughbore  252  therein. If the gap filler  250  is a separate insert element from tubular retainer  228 , the insert  250  can be made of any suitable material, such as plastics or the like. It is sized to fit snugly at the bottom of the axial bore  241  of the needle retainer  228  with the funnel-shaped throughbore  252  properly aligned with the needle passageway  234  and the tubular extension passageway  226 .  
         [0050]    Turning now to FIG. 6, there is shown another needle assembly embodiment of this invention, generally designated by reference numeral  310 , which is installed on the conventional syringe  212  shown in FIG. 2. Needle assembly  310  can be used to inject vaccine or other fluids from chamber  216  of syringe  212 . In this embodiment of the invention, the syringe  212  is also identical to the conventional syringe  112  described previously. The needle assembly  310  in this embodiment includes an injection needle  333  and a needle retainer  328 . The needle retainer  328  is identical to needle retainer  228 , previously described in connection with needle assembly  210  of FIG. 2, and includes an identical tubular gap filler or insert  350 .  
         [0051]    However, in this embodiment of the invention, the needle  233  is an injection needle and includes a piercing tip  330  substantially identical to the standard tip  130  previously described for needle  133 , as shown in FIG. 1. The piercing tip  330  may be necessary in order to inject the live cell vaccine or other fluid contained in chamber  216  into the desired compartment for delivering the vaccine to the bird or avian embryo.  
         [0052]    When the live cell vaccine is being injected from the syringe  212 , the tubular gap filler  350  and throughbore  352  also eliminate turbulence in this area. The fluid is pushed out of chamber  316  by a plunger (not shown) and into the passageway  326 . The fluid then flows into the funnel-shaped throughbore  352 . The flow of the fluid is slow and smooth. As the fluid travels through the throughbore  352 , it continues into the center passageway  334  of the needle  310 . The fluid then flows out of the tip  332 .  
         [0053]    It has been found that there is considerably less damage to the live cells when injecting a live cell vaccine or other fluid out of a standard slanted needle tip, such as tip  332  shown in FIG. 5 and tip  132  shown in FIG. 1, then when attempting to draw live cell vaccine or other fluids into the central needle passageway through such a tip. Hence, the damage imparted to a live cell vaccine which is injected out of syringe  212  through tip  332  is minimal and there is very little live cell destruction or reduction of the PFUs. The standard needle tip construction as embodied in tip  332  is preferred for injecting the live cell vaccines, such as Marek&#39;s vaccine, in as much the sharp piercing point  330  may be necessary for transferring the vaccine from the syringe chamber  316 .  
         [0054]    In transferring live cell vaccines, such as Marek&#39;s vaccine, in accordance with the present invention from their original ampules to a container for delivering the vaccine to the birds or other avian embryo, a sterile needle assembly  228  is assembled onto a sterile syringe  212  to form the needle and syringe assembly illustrated in FIG. 2. The needle tip  232  is then inserted into the ampule containing the live cell vaccine, and the vaccine is slowly drawn into and through the needle  233  in central passageway  234  and then into the syringe chamber  216 . The presence of the unique open mouthed or funnel-shaped tip  232  on the end of needle  233  and the filler or insert  250  serve to promote laminar flow and reduce turbulence during the syringe filling operation. Once the vaccine in the ampule has been exhausted or the syringe chamber  216  has been filled, the needle assembly  210  is removed from the syringe  212  by turning the tubular retainer  228  to disengage outwardly extending flange  238  from the internal male threads  225  on collar  224 . A new and sterile needle assembly  310  is then screw threadedly engaged onto the syringe  212 , now containing the vaccine in the chamber  216 , to form the assembly shown in FIG. 6. Of course, if a piercing tip  330  is not necessary to transfer the vaccine or other fluid from syringe chamber  216  to the desired container, it could be possible to use the original needle assembly  210 , without substituting the alternate needle assembly  310 .  
         [0055]    It is contemplated as part of the present invention that the needle assemblies  210  and  310  will be provided to the poultry operators or vaccine users in pairs as a set. Then, the operator or user will have one needle assembly corresponding to assembly  210  to draw the vaccine from the ampule into the syringe and a second needle assembly corresponding to assembly  310  to dispense the vaccine out of the syringe.  
         [0056]    Turning now to FIG. 7, there is shown another needle assembly embodiment of this invention, generally designated by reference numeral  410 , which includes a breakaway needle. The needle assembly  410  can be used to draw concentrated live cell vaccines or other fluids into chamber  216  of the syringe  212  as well as inject the vaccine or other fluids from the syringe  212 . In this embodiment of the invention, the syringe  212  is also identical to the conventional syringe  112  previously described, and the needle assembly  410  includes a needle  433  and a needle retainer  428 . The needle retainer  428  is identical to needle retainers  228  and  338 , previously described in connection with needle assemblies  210  and  310  of FIGS. 2 and 6, and includes an identical tubular gap filler or insert  450 .  
         [0057]    The needle  433  includes a weakened area  460  near the outer tip  432  which divides the needle  433  into a main needle portion  462  and a removable needle end  464 . The weakened area  460  is at a sharp diagonal to the longitudinal axis of the needle such that upon removal of the removable needle end  464 , the main needle portion  460  is left with a sharp pointed needle tip  466 , preferably of standard configuration. The weakened area  460  can be molded into the wall of the needle, if the needle  433  is molded from plastic, or the weakened area  460  can be scored or ground on the outer surface of the needle, or otherwise formed in the needle wall, if the needle  433  is made of metal.  
         [0058]    When using the needle assembly  410  in conjunction with syringe  212 , live cell vaccines, such as Marek&#39;s vaccine, or other live cell fluids can be drawn into syringe chamber  216  through the open mouth  462  of the funnel shaped tip  460  without encountering the sharp edges normally associated with a standard needle tip. Once the vaccine or other fluid has been drawn into the syringe chamber  216  with the smooth transition flow provided by insert or filler  450 , the needle breakaway end  464  can be detached from main needle portion  462  along weakened area  460 . This leave main needle portion  462  with a standard piercing needle tip  466  which can be used to pierce an injection port of a standard diluent bag or other container for injecting the vaccine or other fluid from the syringe chamber  216  out through the needle tip  466 .  
         [0059]    While the needle assemblies of the present invention have been described specifically for use with live cell vaccines and other fluids in general, and Marek vaccine in particular, the needle assemblies have broad application. It is contemplated that the needle assemblies of the present invention could be used with Probiotics (Lactobacillus) or any other microorganism in a fluid suspension. Additional uses could be with sperm and blood cells, or any other live cell fluid or live organism that might be injured or destroyed by turbulence or sharp edges of a standard needle assembly.  
         [0060]    The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.