/ 6C Poultry Science
Mimeograph Series No. PY 69-2
FS06 February, 1969; 200 copies
K) (A-au


Before oviposition:


Oviposition:

Between oviposition and
incubation:


Florida Agricultural
Experiment Station
Gainesville, Florida
32601


DEVELOPMENT OF THE CHICKEN EMBRYO HUME LIBRARY

R. A. Voltle and H. R. Wilson MAR 319


Fertilization F voridi I
Division and gro tVF l ;- Fy ,, 0-
Segregation of cells Into groups
of special function


Several hundred cells


No growth; stage of inactive
embryonic life (If temperature is
kept below physiological zero =800 F).


During incubation:


First Day:
8 hours
18 hours


hours
hours
hours
hours


24 hours

Second Day:
25 hours
30 hours
35 hours
38 hours
42 hours


Third Day:
50 hours

60 hours
62 hours
64 hours
70 hours


Appearance of primitive streak
Appearance of primitive gut-primordial
germ cells appear In germinal crescent
Appearance of vertebral column
Appearance of neural groove
Appearance of somites
Appearance of blood Islands-vitelline
circulation
Appearance of eye (6 somites)


Appearance of heart
Appearance of amnion (protection)
Appearance of ear (14 somites)
Cranial flexure and torsion evident
Heart beats-beginning of yolk sac
(19 somites)


Appearance of amnion-chick has
turned on left side
Appearance of nasal pits
Appearance of posterior limb buds
Appearance of anterior limb buds
Appearance of allantois;
(a) embryonic respiratory system
(b) holds kidney excretions
(c) aids in absorption of albumen
by embryo
(d) connected to future cloaca







-2-


Fourth Day:

Fifth Day:


Sixth Day:


Appearance of tongue and esophagus

Appearance of proventriculus,
gizzard, reproductive organs and
differentiation of sex

Appearance of beak and egg-tooth-
voluntary movement-duodenal loop
formed

Allantois and chorlon serosaa)
anastomose and lay against shell-
ceca and digits appear


Seventh Day:



Eighth Day:

Ninth Day:


Feather tracts appear


Embryo bird-like In appearance-
growth of allantols nearly complete


Beak begins to harden


Eleventh Day:



Thirteenth Day:




Fourteenth Day:


Fifteenth Day:

Sixteenth Day:



Seventeenth Day:



Eighteenth Day:


Nineteenth Day:


Abdominal walls established, loops
of Intestine are seen hanging in
yolk sac.

Appearance of scales, claws, down
and muscle-cartilaginous skeleton
is complete and ossification is
progressing

Embryo turns head toward blunt end
of egg

Small Intestines taken into abdomen

Beak, nails and scales relatively
cornified-albumen practically gone
and yolk increasingly important

Amniotic fluid decreases-head
under right wing with beak toward
air cell

Transfer of embryo to hatching
trays-turning no longer required

Yolk sac begins to enter body
cavity and amniotic fluid disappears
(embryo swallows it)-beak pierces
air cell and lungs function slightly


Tenth Day:





-3-


Twentieth Day:




Twenty-first Day:









For information on incubation
following references:


Kalch, L. W. A Small Display
Extension Circular.


Yolk sac drawn completely into
body-pulmonary respiration starts-
allantoic circulation and respiration
cease and allantois dries up

Normal hatching
(a) head under right wing
(b) legs toward head
(c) pipping
(d) shell quite brittle as some
calcium of the shell is used
to build skeleton



and embryonic development consult the



Incubator, 1961. University of Florida


Romanoff, A. L. 1960. The Avian Embryo. The Macmillan Company, New
York.


Patten, B. M. 1964. Foundations of Embryology. Mcgraw-Hill, Inc.
New York, 2nd edition.


Lillie, F. R.
Company.


1930. The Development of the Chick. Henry Holt and
New York, 2nd edition, Revised.