The document provides instructions for windowing chicken eggs in order to access the developing embryo for experimental studies. The key steps are: 1. Candling the egg to locate the embryo. 2. Scrapping a small window in the eggshell directly above the embryo using sandpaper. 3. Carefully cutting a 1cm x 1cm window and removing the shell without disturbing the membrane below. 4. The window allows observation and manipulation of the embryo, such as adding test reagents. The window is then sealed with parafilm and the egg returned to incubation. Windowing provides non-invasive access to the embryo for developmental studies using the chicken egg model.

1. June Hayden R. Sinson
Ramon Magsaysay High School - Espaǹa
Arturo A. Tolentino,
Caloocan City Science High School

2.  The
study of development has been
greatly aided by the use of the chick
embryo as an experimental model.

3. It is necessary to open
the eggshell and
reclose it without
perturbing the
embryo's growth. The
embryo can be
examined at successive
developmental stages
by re-opening the
eggshell.


4. Protocol

5. Maintain
at 37°C
with relative
humidity that
was set above
60%, remove the
eggs from the
incubator.

6.  Turn
eggs 90
degrees so that the
large base lies
horizontal where
your embryo is
located.

7. Saturate
a stack of nonsterile gauze with 70%
ethanol.
Use
two to three pieces
to swab up to 5 eggs.
Discard when the
gauze is soiled.

8.  Cut
and place a 1" x 1" piece of plastic
tape just left of the base to protect the
area where the albumen will be drawn
out.

9.  Use
the point of a
pair of scissors to
make a small hole in
the middle of the
tape.

10.  Using
a 10 cc
syringe with an 18gauge, 1-inch
needle, slowly drill
the needle through
the hole made by the
scissors.

11.  Drive
the needle
down at a 45°C angle
towards the bottom
of the egg.
 Tilt the needle
towards the center
and draw up 3 to 4
mL of albumen.

12.  Cut
a 3" x 3" piece of plastic tape and
stretch it to fit on the top of the egg.
Extend the corners of the square around
the rounded ends of the horizontal
surface of the eggs, being careful not to
pull too hard.
Pull the tape so that it
is tight against the
surface of the eggs
with no folds.

13.  Using
a pair of sharpstraight 4" dissection
scissors, twist a hole
into the bottom
center of the area
where the tape was
placed.

14.  Slowly
guide the
lower blade of the
scissors into the egg
being sure to keep
the tips up against
the inside of the
shell. Direct
the
blade towards the
base and slowly
begin to cut the
shell.

15.  Remove
the
scissors and repeat
going
in
the
opposite direction
until only a small
bit of the egg
remains attached.
Check to be sure
the egg is fertilized.
Shut the window.

16.  Cut
about a 2-3" long by 1/2" wide plastic tape and
shut the window so it fits back into the hole that
was cut. Take another 1 x 1" piece of tape and seal
the hole from which the egg was drained. Use a
pair of forceps to reopen the
egg to do any manipulations.
When you're ready to return
the eggs to the incubator, cut a
piece of tape that is large
enough to seal the window and
cover the entire horizontal
surface of the egg.

18.  http://www.ncbi.nlm.nih.gov
 J Vis
Exp. 2007; (8): 306.
Published online 2007 October
1. doi: 10.3791/306
PMCID: PMC2562489
Matthew J. Korn and Karina S. Cramer
 http://www.youtube.com :
Windowing Chicken Eggs for
Developmental Studies

20. Avian egg is a useful animal model for
studies concerning early embryonic
development.
The model is particularly advantageous
of the ease by which the avian embryo
may be accessed and handled.
Numerous bioassays revolving around
avian embryos have been developed..

21. Avian eggs may be used for teratogenicity
studies.
Choriooallantoic membrane (CAM assay.
Egg windowing
• Process by which the egg is
opened and the embryo revealed
for manipulation.

22. 1.Perform egg candling in order to
determine the position of the
embryo.
This can be done by holding the egg in
front of a light source.

23. (Source:http://www.pic2fly.com/Candling-Chicken-Egg-Pictures.html)
This step is necessary in order to ensure
that the windowing be performed
exactly on the top of the embryo

24. 2. Using sandpaper, scrape the egg shell
directly on top of the embryo.
3. Once the shell is thin enough, cut a
small window (1 cm x 1 cm) into the
egg shell. Remove the egg shell first
before cutting through the shell
membrane. Once the window has
been cut,
it may be enlarged
depending on the need.

25. 4. Observe the embryo.
5. Add 10 drops of the test reagent.
6. Cover the open window with
parafilm and return to the incubator.
References:
G. Speksnijder & R. Ivarie. 2000. A Modified Method of Shell Windowing for Producing Somatic or Germline
Chimeras in Fertilized Chicken Eggs. Poultry of Science 79:1430-1433.
UP seminar materials , acquired, April, 2013.

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