CHICKEN EMBRYO

Gallus gallus
The Chicken embryo is a staple educational tool in developmental biology.Their availability and similarities with mammalian embryo, help shape our present understanding of embryology. After 21 days of incubation, the chick attempts to break out of its shell, pushing its beak through the air cell. Since the specimens were received out of the egg and without its yoke, I lacked the ability to document the chickenís interaction in its element. The specimens document a range from 5, 6, 9, 12, to 18 days of development.

PHOTOGRAPHING THE EMBRYO

SUPPLIES
camera
two sets of fiber optic lights
glass cell approx. 5"x5"
water that has sat out in the open for 1 day
black velvet fabric large enough to cover the bottom of the glass cell

PROCEDURES
The chicken embryo is a semi-transparent and monotone subject. The transparent flesh lends itself well to back light, which causes the skin to appear to glow.  The choice of background is a crucial prop that helps determine the success of the image for its application. For scientific and documentation purposes, black is the best choice to contrast the flesh tone embryo and emphasize its subtle details. Using a white background makes the translucent skin difficult to distinguish between the subject and its background. However, done correctly, a white background can produce an aesthetically pleasing photo, articulating its neutral tones.

The chicken embryo if filled with fluids. If taken out of the water, its delicate cavities will collapse, loosing the significance of its bodily form. Photographing the embryo through water maintains its structure. A second advantage of photographing the embryo under water removes any specular highlights while diffusing the light that falls on the subject. However, the diffusion does reduce the contrast. Bumping up the contrast either through the lighting technique or through the digital file will be helpful.

In the same way that air bubbles form on the sides of an open bottle of water, bubbles will form on the embryonic body. This produces unpleasant artifacts on your image. To reduce this issue, let the water sit out for a day so the gas in the water have a chance to escape. If the bubbles still remain on your subject, try shaking it off, otherwise as a final attempt, they can be removed through Photoshop.  Fill the cell with water so it just covers the embryo. Too much water and the embryo will float around uncontrollably. Too little water and unwanted specular highlights will show up on its wet surface.

Place the glass cell on top of the black velvet. Black velvet produces a rich black background. Set the fiber optic lights at the bottom of the cell on two opposite sides of the cell. My lighting ratio was at 1:2. One light shining towards the front of the embryo and the other shining on the back. The head of the chicken is usually the main focus point. Let the brighter light shine on the anterior body. Placing the lights at the very bottom of the cell allows the light to shine across and through the transparent embryo, creating a glow on its edges. The side lighting also forms shadows on the embryo, emphasizing its bulbous eyes and porous skin.

Chicken embryos are a fascinating subject both on a scientific level and aesthetical level. The continual observation and documentation of chick embryo helps to educate the development of organisms generate and are manipulated.

DAY 5
Reproductive organs begin to form
The bones of the legs & the crop begin to develop.

DAY 6
Wing is bent at the elbow
The beak is more prominent
No egg tooth is visible yet
10 DAY
The distal segments of limbs are longer
Nostril is a narrow slit
Flight feathers are noticeable
Lower eyelid has grown up to level of cornea
Circumference of lids is a narrowing ellipse

12 DAY
Primary scales form over entire surface of leg
Feather germs surround auditory opening
Upper eyelid is covered with feather germs
Lower eyelid covers 2/3 to 3/4 of cornea

18 DAY
Beak length-4.8mm
Third toe length-16.7mm
Facts sheet reference:
http://www.rit.edu/~gtfsbi/genbiol/chicklab.htm
PHOTOGRAPHY & COPY PRODUCED BY
MICHELLE LEUNG
michelleleung8@gmail.com
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Return to index of articles by students on the 'Principles and techniques of photomacrography' course, November 2004,
Biomedical Photographic Communications (BPC)
program at the Rochester Institute of Technology (RIT).

Article hosted on Micscape Magazine (Microscopy-UK).

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