EXPERIMENTAL CHICK EMBRYOLOGY ^^21 



Provided ty the Student : 



12 petri dishes {h" diameter) 



12 watch crystals (2" diameter) 



2 regulation finger howla 



2 Erlenmeyer flasks (500 cc.) 



2 Erlenmeyer flasks (125 cc.) 



1 graduated cylinder (100 cc.) 



1 graduated cylinder (10 cc. ) 



2 wide-mouthed pipettes, smooth edges ( inside diameter h mm. ) 

 2 fine pipettes (inside diameter 1 mm.) 



12 regular medicine droppers 

 6 shell depression slides 



^ oz. round cover glasses, #1 thickness (to cover depression) 

 1 small glass tumbler, cotton in hottom and partially filled with ^0'f> alcohol 

 for sterilization of operating Instruments. 

 Absorbent cotton 



Operating equipment : 



1 hack-saw with extra blades (ampoule saw may be satisfactory) 



2 watchmaker's forceps, #5 



1 pair regulation forceps 



2 steel needles, ground to fine points 

 1 pair coarse scissors (large) 



1 pair fine scissors (small) 



PREPARATION OF EQUIPMENT 



All glassware and instruments should be thoroughly washed in non-caustic soapy water; 

 rinsed in hot, running tap water; and put aside to dry on a deem cloth towel. The metal 

 Instruments and culture dishes may be further sterilized in the dry sterilizing oven while 

 the solutions should be autoclaved at 15 pounds for at least 15 minutes. Thereafter the 

 operating equipment may be kept In 70^ alcohol to which a drop of iodine solution has been 

 added. The greatest source of bacterial or mold infection is not from such pre-sterillzed 

 equipment but rather from the hands and breath of the operator. One should work in a 

 draft-free room, away from windows, and the embryos should be exposed to the air only when 

 absolutely necessary. 



PRELIMINARY SUGGESTIONS 



1. Become re-acqualnted with the normal morphogenesis of the chick egg. 



2. Select eggs that are uniform in size, shape, and color for any one experiment. 



5. Check the incubator temperature and humidity at least once each day. Temperatures 

 above 105 °F. are more deleterious than below that level. 



k, Bemember that genetic factored may contribute to high mortality. It cannot be 



stressed too frequently that one must become thoroughly acquainted with the source 

 of the eggs being used. 



5- Do not wash or submerge the eggs for long In water because the embryo normally 



breathes air through its porous shell. Washing will remove a thin surface cuticle 

 which protects the chick embryo against the Invasion of microorganisms. Prior to 

 operations within the egg, sterilization of the shell and exposed shell membrane 

 may be accomplished with a cotton swab soaked in 70^ alcohol, 1% iodine in alcohol, 

 or chlorazene. The chlorazene is made up by adding 5 tablets to a quart of warm 

 water. 



6. The membranes should be observed Just prior to the time for hatching. When the 

 extra-embryonic circulation begins to regress, the incubation temperature can be 

 lowered and the humidity raised. Should the chick's beak happen to lie beneath 

 the artificial window, this window should be removed on the 19th or 20th day. 

 Frequently operated chicks must be assisted In the hatching process on ttoe 21st 

 day. Do not attempt to remove the chick until the yolk sac is completely re- 

 tracted into the chick mid-gut. 



