Virtual Chicken
The Female Reproductive Tract
Advanced Level
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Role of the Avian Female
Reproductive Tract
 Manufacture ova and egg components
• Ova
• Yolk
• Albumen
• Shell
 Site of fetilization
 Sperm is stored and transported within the
female tract
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Ovary -- 2 functions
 Produce ova
• germinal disk - will
become the embryo
when fertilized
• Yolk-nutrition for the
growing embryo
 Endocrine function
• Estrogen, androgens,
and progesterone
Oviduct
 Transport
 Packaging
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Ovary Structure

Outer cortex contain the
ovarian follicles
• >12000 follicles
– Oocytes
– Steroid producing
cell layers
» Granulosa
» Theca

Inner Medulla
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
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Virtual Chicken
The Female Reproductive Tract
Ovarian Follicle
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Time ova spends in each section

Infundibulum





≤ 1 hour
Captures ova
Secretes outer membrane
First albumen
Magnum


2 – 3 hours
Albumen




± 1 hour
Inner
Outer Shell Membranes
Shell gland




Avidin
Ovalbumin
Lysozyme
Isthmus




Oviduct
Fast Facts
20 – 26 hours
Plumping
Shell deposition
Vagina




Just a few minutes
Sperm storage
Cuticle
Pigment
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Embryonic Origin of the Ovary

Before hatching, the embryo is in an “indifferent”
stage having the beginnings of both male and female
reproductive organs.





Primordial germ cells (PGC’s) that will become eggs or
sperm have formed in the embryo before oviposition.
PGC’s circulate in the blood
Migrate into the mesoderm and colonize “gonadal ridge”
96 hours into incubation: PGC’s migrate to left side if the
embryo is genetically female
Eventually forms the ovary
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Development of the Ovary

Cortex – outer cell layers of embryonic ovary


Medulla-inner cell layers


Proliferation of PGCs
Right ovary stops developing and degenerates



PCGs and connective tissue
First sex specific differentiation is thickening of the cortex at 7 days of age


PGCs
Some medullary tissue may persist in right oviduct
Can form ovotestis if the ovary ever becomes damaged
Left ovary continues to develop
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Oviduct



Embryo has both male (Wolfian) and
female (Mullerian) reproductive duct
system.
Mullerian duct becomes the Oviduct
Wolfian duct may persist as a vestigial
structure
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Yolk Formation and Maturation of the Ovum

White yolk
 Core of the yolk
 Female pronucleus (female genetic material)

Yellow yolk
 Deposited in layers on white yolk
 Yellow because of fat soluble pigments from feed
 Female pronucleus rises through yellow yolk on stalk
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Yolk Formation and Maturation of the Ovum


Rapid deposition of yellow yolk for 7-10 days prior to ovulation
Yolk material is formed as droplets or spheres much like fat
droplets in milk.
 Yolk formation is estrogen dependent
 Yolk components formed in liver
 Particles of “Very Low Density Lipoproteins” (VLDL)
 12% protein
 88% lipid
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Yolk Formation and Maturation of the Ovum
 Proteins
 Apo-B, Apo-VLDL-II
 Vitellogenin
 Phosvitin, Lipovitellin
 Plasma proteins
 Albumin
 IgG (antibodies to protect chick)
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Yolk Formation and Maturation of the Ovum
 Lipids



Triglycerides (70 – 75%)
 Can be somewhat
manipulated by changing
hen’s diet
 Mainly palmitic, oleic acids
Phospholipids (20-25%)
Cholesterol (only 4%!)
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Yolk Formation and Maturation of the Ovum
 4 membranes enclose the
yolk (from inside to out)




Vitelline membrane
Perivitelline membrane
Middle continuous layer
Extravitelline layer
 Blastodisc
 Location of the embryo
 Floats on white yolk
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Follicular Hierarchy



Follicles develop in an orderly
hierarchy
Control of the order of follicle
development is not well understood
Recruitment of follicles into the
hierarchy:

May be adrenal regulated



The Adrenal glands are essentially
embedded in ovary
Nerve endings on thecal cells
If nerves are cut: many follicles mature
at once
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Hormone production
by follicles
 Steroidogenesis: Controlled by pituitary hormones:
FSH and LH
 Estrogen and androgen
 Estrogen production dominates as the follicle
begins to accumulate yolk then declines as follicle
nears maturation
 Androgen and progesterone production maximum
about 3 days prior to ovulation
 Androgen production ends at just before ovulation
 Progesterone production continues after ovulation
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Endocrine Control of Development

Follicle stimulating hormone (FSH)
 Granulosa cell differentiation
 Progesterone production

Luteinizing hormone (LH)
 Androgens
 Estrogens
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Post Ovulatory Follicle


In mammals, the parts of the follicle
remaining after ovulation become the “corpus
luteum” and continues to produce
progesterone to support pregnancy
In birds, steroidogenic capacity is retained by
the postovulatory follicle for 24 hours
 Probably has no function since birds don’t get
pregnant
 Gone by 6 days
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Ovulatory Cycle


Interval between consecutive ovulations
Controlled by circadian rhythms
 Clock reset at dusk: open period for oviposition begins 15
hours after dusk



Open period: Oviposition and ovulations occur during
an 8 hour period
Ovulation 30 – 45 minutes after oviposition
LH release controls ovulation
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Ovulation

Structure of the follicle causes
expulsion of the ovum

Stigma: avascular area



Collagen structure weaker
Proteolytic enzymes -digest
and weaken the membranes
Myofibrils - contract and cause
the membranes to rupture
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Functions of the Egg

Container
 Holds and protects the organic and
inorganic materials required to
produce the chick

Controlled environment
 Controls entry of microorganisms,
gas exchange, moisture loss
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Egg Formation




Starts in a hen’s ovary
Ovum
 Ovum is surrounded by the
vitelline membrane produced by
the ovary
 Ovum stores nutrients as yolk
granules for use by the embryo
White yolk
 Most is located directly below the
nucleus
Yellow yolk
 Seven or eight day before the
ovum is ovulated, yellow and
white yolk are laid down in layers
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Eggshell
 Multiple layers
 function together to
protect the embryo
 Provide the correct
environment for embryonic
development
 Inner shell membrane
 In contact with
albumen/chorioallantois
 Nonfibrous on surface facing
embryo
 Fibous on outer surface
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Eggshell
 Capable of withstanding 100
psi internal pressure
 Mammillary layer
 Palisade layer
 50% of the strength of the
shell
 Columns of calcium
carbonate (calcite)
 Organic matrix
 Surface crystal layer
 Pores
Calcite crystals
Mammilary cores
Outer shell
membrane
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Outer Shell Membrane



Stacked on top of inner shell membrane,
except at air cell
Mat of fibers, intermeshed with fibers of
inner membrane
Mammillary cores
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
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Virtual Chicken
The Female Reproductive Tract
Cuticle
 Protein
 Plugs pores
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Shell Formation

Two Main components of egg shell mineral
 Calcium – from diet
 Carbonate – from respiration
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
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Virtual Chicken
The Female Reproductive Tract
Source and Deposition of Calcium

Eggshell takes more calcium than hen has in blood and is placed on
the shell faster than hen can absorb calcium from the gut

Hen derives calcium for eggshell from diet and from stored sources
 Sort term calcium storage in crop
 Long term calcium storage in bone
 Medullary bone - rapidly mobilizable calcium source
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Source and Deposition
of Calcium




Ionized (free) calcium is taken from
blood, deposited on eggshell
Blood calcium replaced by calcium
released from medullary bone
Shell gland maintains a supersaturated
calcium solution so that calcium
precipitates out on sell membranes
Complex endocrine mechanisms to
control calcium utilization


Dihydroxyvitamin D
Parathyroid hormone
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Source and Deposition of Calcium

Carbonate derived from CO2 from cell respiration
 Carbonic anhydrase is the enzyme responsible (mostly in red blood cells)
 Water and CO2 form bicarbonate and free H+ ions
 Carbonate secreted in shell gland to form egg shell
 H+ ions diffuse back into blood and lower blood pH (blood becomes acidic)
 Increases respiration
 Blows off CO2 + H+ (blood becomes alkaline)
 Dietary and environmental conditions can alter this and cause problems with
eggshell formation.
 High temperatures
 High breathing rate (panting) to cool - blows off too much CO2
 Acidic diet or water
 Alkaline diet or water
 Metabolic Acidosis
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Egg Shell Quality

Shell quality is associated with
hatchability


 Hatchability
Shell quality declines the longer a hen
is in production


 Shell quality
 Shell quality
 Hatchability
Season of the year, hen strain,
environment temperature, nutrition


Hot weather =  Shell quality
Poor nutrition =  Shell quality
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Measuring Shell Quality

Appearance
 Rough Shell
 Misshapen



Shell thickness
Shell strength
Shell porosity
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
Interior Egg Quality


Tremulous air cells
Albumen quality
 Haugh units
 Albumen height corrected for egg
size
 Higher Haugh unit = better
hatchability
 Haugh units should be 80 or
higher for good hatch
 Loss in albumen height due to
loss of specific protein: ovomucin
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract
Virtual Chicken
The Female Reproductive Tract
The End
Questions?
Funded by: USDA Higher Education Challenge Grant Agreement No. 2003-38411-13479
and
Poultry Products Safety & Quality (PPSQ) Program
Auburn University, Alabama
© 2006 The Virtual Chicken: The Female Reproductive Tract