25 - Avian Fertilization & Development

Question 1

Mitotic division occurs when? Embryonic development?

Answer 1

Mitotic division from yolk -> clocaca

Once egg is externalized, embryonic development

Question 2

Fertilization and embryonic development occurs where?

Answer 2

In the germinal disk of the yolk

Question 3

Polyspermy in avian

Answer 3

Normal in fertilization (sperm very concentrated)
Several sperm penetrate membranes of the germinal disk and form male pronuclei

Question 4

What is syngamy

Answer 4

1 male pronuclei positioned adjacent to the female pronuclei
1 male pronuclei fuses w female pronuclei, forms a zygote and mitotic division begins

Question 5

At the time of laying, the embryo contains how many cells?

Answer 5

30,000-60,000

Question 6

What is developmental diapause?**

Answer 6

• development is dependent on incubation temperatures (requires ~37.5C)
• fertilized eggs can be stored/transported prior to incubation (below 21C = no development)
• development of fert eggs can be arrested for up to 7 days with little affect on hatchability

Question 7

Describe avian incubation and development

Answer 7

After 38h of incubation beating heart is visible
Blood supply of yolk sac developed at 4 days
Embryo highly developed at 10.5 days incubation

Readily available nutrients in egg allow for rapid development

Question 8

Extra-embryonic membranes

Answer 8

Yolk sac, amnion, chorion, allantois

Question 9

What is the yolk sac

Answer 9

First EE membrane to develop
Endoderm surrouds the yolk within the inner shell membrane & is highly vascular. Provides nutrients to development embryo.

Question 10

What is the amnion

Answer 10

Developed by 4 days incubation
Surrounds developing embryo to protect against mechanical damage & dehydration.
Provides protein from albumen that enters amniotic fluid.
Formed from ectoderm, endoderm and mesoderm

Question 11

What is the chorion

Answer 11

Develops next to the inner membrane from the ectoderm, endoderm and mesoderm parallel to the amnion
Close relationship with allantois

Question 12

What is the allantois

Answer 12

Developed by day 4 incubation from hind-gut of the embryo for waste collection

Question 13

What acts as the lung of the embryo during last 2 weeks of incubation? How?

Answer 13

The chorion and the allantois at as the lung
Exchange carbon dioxide for O2 coming through pores of the shell

Question 14

Slides 14-17

Answer 14

Look

Question 15

Gestation/incubation in chicken? Turkeys?

Answer 15

Chicken = 21 days
Turkey = 28 days

Avian more efficient than all other species