Formation of the Egg

WAQAR UL HASSAN

2011-ag-2155

University of Agriculture Faisalabad

Formation of the Egg

Egg consists of reproductive cell

Cell is located on surface of yolk

Cell are surrounded by albumen, shell

membranes, shell and cuticle

OVARY Ovary is a quiet mass of small follicles containing ova

Some ova are large to be visually seen

Full-size yolks necessary for egg production

Formation of yolk Yolk is not true reproductive cell

Yolk is a source of food material

When the pullet reaches sexual maturity a sequence of

hormonal changes occur

The FSH produced by anterior pituitary gland

Active ovary begins to generate hormones

That are estrogen, progesterone and testosterone

The first yolk to begin maturing does so as major amount of the

yolk material

A day or two later, the second yolk begins to develop and so on,

until at the time the first egg is laid

About 10 days are required for an individual yolk to

mature

The color present in the yolk is due to xanthophylls

Egg yolk is composed mainly of fats and proteins

Ovulation At maturity the ova are released a process known as

ovulation

Each ovum hangs on the ovary to enter the oviduct by a

process known as ovulation

Each ovum hangs on the ovary by a narrow stalk

When the ovum is mature the hormone progesterone produced

by the ovary

That cause the release of the luteinizing hormone (LH) from

anterior pituitary

The time necessary grow an egg to transverse the oviduct

varies with individuals

Most hens lay successive eggs with time intervals of 23 to26

hours

Defective Egg Shells

When the normal interval of about 23 to 26 hours between

ovulations is broken

More eggs are produced with defective shell

From 5 to 7% of the eggs produced have some form of the

defective shell

Yolk size affects egg size

The size of the completed egg is more closely associated

with yolk size

Oviduct Oviduct is a long tube

In which yolk passes and remaining proteins of egg are

secreted

Parts of oviduct Oviduct have 5 major parts

1. Infundibulum

2. Magnum

3. Ishmus

4. Uterus

5. Vagina

1. Infundibulum

The funnel shaped upper portion of the oviduct is the

infundibulum

Length is approximately 3.5 inches (9 cm)

2. Magnum

The magnum is the albumen secreting portion of the

oviduct

Length is about 13 inches (33 cm) long in average laying

hen

It takes 2 to 3 hours for the developing egg to pass

through the magnum

3. Isthmus The developing egg is forced into the isthmus

Length is 4 inches (10 cm)

It remains for 75 minutes

Here the inner and outer shell membranes are formed

4. Uterus (shell gland)

Uterus is formed 4.0 to 4.7 inches (10 to 12 cm) long in the

laying hens

Developing egg normally remains in the uterus from 18 to 20

hours

Much longer then other section of the oviduct

5. Vagina The final section of the oviduct is the vagina

Length is 4.7 inches (12cm) in a bird during egg

production

Normally, the egg is held in the vagina for only a few

minutes

Vagina has no role in egg formation

Thanks