Site of Fertilization – Birds vs Domestic Animals

The site of fertilization in birds & domestic animals are respectively:

Correct Answer: Infundibulum (Birds) & Ampulla/Ampullary-isthmic junction (Domestic Animals)

The site of fertilization differs between birds and domestic mammals:

• Birds: Fertilization occurs in the Infundibulum — the most cranial/funnel-shaped part of the oviduct. The infundibulum picks up the ovulated yolk (ovum) from the ovary, and fertilization by stored sperm occurs here.
• Domestic animals: Fertilization occurs at the Ampullary-isthmic junction of the oviduct (Fallopian tube) — where the ampulla (wider, convoluted part) meets the isthmus (narrower part).

Why the Difference?

• In birds, the ovum is surrounded by yolk and albumen is added as it travels down — fertilization must occur BEFORE albumen and shell are added, hence at the very top (infundibulum).
• In mammals, fertilization occurs in the oviduct at the ampullary-isthmic junction and the fertilized ovum then moves to the uterus for implantation.