Bird Ovaries: Developing Ova inside Follicle

OogenesisOvum (Gamete) Production

(Meiosis Partially Completed at Birth)

Follicle Maturation

Follicle ContainingEgg (= Ovum)

http://www.hiltonpond.org/images/VultureBlackOvum01.jpg

Primary Oocytes: 500 - 2000

Egg (Ovum)

Follicle Maturation

http://www.hiltonpond.org/images/VultureBlackOvum01.jpg

Passerines: 4-5 DaysDucks/Pigeons: 6-8 DaysPenguins: 6-8 Days

Timeframe

Enlargement

Up to 1000X Initial Size

Follicle Maturation:Yolk Contents of Ovum

Materials

• Nutrition (Proteins, Lipids)

• Hormones (e.g., Testosterone)

• Immune Factors (e.g., Carotenoids, Immunoglobins)

• Antioxidants (e.g., Carotenoids,a Vitamin A precursor)

Vitelline Membrane

Yellow Yolk (Day Deposition)

White Yolk (Night Deposition)

Central Latebra (contains clear Vitelline Fluid)

Follicle Maturation:Yolk Anatomy of Ovum

(Germ Spot)

Follicle Maturation:Yolk Content in Altricial versus Precocial Birds

Fig. 14-14 in Gill 2007

Altricial:

Precocial:

http://partnersah.vet.cornell.edu/avian-atlas/sites/agilestaging.library.cornell.edu.avian-atlas/files/avian_atlas_assets/3.4.08.2DSC00050%20x750.jpg

Follicle Maturation: Mature and Atretic Follicles

Stigma ofMaturing Follicle

Atretic Follicles

Ovulation

Clutch

Fertilization

Sex Determination: Birds vs. Mammals

Gynandromorphs

Egg Development: Magnum(Albumin and Chalaza Deposition)

Egg Development: Magnum(Albumin and Chalazae Deposition)

Composition: Water (90%) Protein (10%)

Function: Water Supply Shock Absorption Insulation

Albumin

“Egg Whites”

Egg Development: Magnum

1) Chalazal Albumin (Dense)

2) Inner Albumin (Watery)

4) Outer Albumin (Watery)

3) Fibrous Albumin (Viscous)

Chalaza – Twisted, Ropy Albumin

Egg Development: Isthmus(Additional Albumin, Shell Membrane (2) Deposition)

Egg Development: Isthmus(Additional Albumin, Outer and Inner Shell Membrane

Deposition)

Inner Shell Membrane

Outer Shell Membrane

(Air Space)

Egg Development: Uterus(with Shell Gland)

Egg Development: Uterus (with Shell Gland)

• Additional Albumin

• Shell

• Pigments

Papillae

Fig. 8-76 in Podulka et al. 2004

Function

Fig. 8-66 in Podulka et al. 2004

Egg Development: Uterus (with Shell Gland)(Cuticle, Calcite Crystals, Pore, Shell Membranes, Chorioallantoic Membrane)

Egg Development: Uterus (with Shell Gland)(Consequences of Shell Porosity)

DDT

Egg Development: Consequences of Egg Shell Porosity

Embryo Development: Yolk Sac and 3 Extra-Embryonic Membranes

3) Chorion 3) Amnion 2) Allantoic Sac

Yolk Sac

Egg Development: Shell Gland (Uterus)(Egg Color: Among Species Variation)

24 25

Spotted Streaked

Egg Development: Shell Gland (Uterus)(Egg Markings: Among Species Variation)

Egg Development: Shell Gland (Uterus)(Egg Markings: Among Species Variation)

Fig. 8-76 in Podulka et al. 2003

Egg Development: Shell Gland (Uterus)(Egg Color and Markings: Among Species Variation)

Egg Development: Shell Gland (Uterus)(Egg Color: Within Species Variation)

Individual Egg Recognition in Colonies(Common Murres only accepts eggs colored like its own)

Common Murre

Egg Development: Shell Gland (Uterus)(Egg Markings and Shape – Within Clutch Variation)

American Crow Clutch

(Adaptive Value?)

Egg Development: Shell Gland (Uterus)(Egg Color: Within Species Variation in “Egg-Dumping” Birds)

Female 1

Female 2

Female 3Northern Masked-Weaver

Egg Expulsion: Vagina and Cloaca

Fig. 4-111 in Podulka et al. 2004

Egg Laying• Many Birds (e.g., Passerines, Woodpeckers) Lay Eggs about

24 Hours Apart

• Some Birds Lay their Eggs Two Days Apart (Ostrich, Herons, Doves, Owls, Hummingbirds, Swifts, Kingfishers, Some Accipiters

• Penguins Lay their Eggs Three to Six Days Apart

• Kiwis lay their Eggs 14-30 Days Apart

Egg Size

Egg Size: Among Species Variation

Fig. 8-69 in Podulka et al. 2003

Fig. 8-71 in Podulka et al. 2003

Egg Size: Among Species Variation(Precocious versus Altricial Birds)

Egg Shape : Among Species Variation

Fig. 8-72 in Podulka et al. 2003

Egg Shape : Among Species VariationNomenclature

Fig. 8-72 in Podulka et al. 2003

Egg Shape – Adaptive Value of Shape

Fig. 8-73 in Podulka et al. 2004

Common Murre

Pyriform Shape Adaptive,But NOT FOUND in otherCliff Nesters

28Swift’s Mating