Avian Production Management

YOLK

The yolk consists of

• Concentric layers of dark and light yolk material, due to differences in their chemical composition
• Latebra is the centre of the yolk, which is a small, nearly circular core of light coloured fluid, which does not completely harden on boiling
• Nucleus of Pander is a cup-shaped structure, which is an extension of the neck of latebra, connecting the base of the germinal disc
• In an infertile egg it is unicellular (ovum) and contains haploid number of chromosomes, called "Blastodisc".  It is circular in shape, with a diameter of about 3.5 mm and with vacuoles in it. Where as in a fertile egg, it is a multicellular structure having diploid number of chromosomes, called "Blastoderm". It is oval in shape, with an average diameter of about 4.5 mm and with no vacuoles in it.
• "Vitelline membrane" is a semi-permeable elastic membrane, surrounding the yolk, separating the yolk material from the albumen