In certain animals a structural condition occurs in which all or most of the paired parts or structures are repeated at regular intervals, along the antero-posterior axis of the body. The body of such animals is made up of a longitudinal series of elements, in each of which all or most of the systems of
1. Foramen Magnum—Opening at back of vertebrate skull. 2. Foramen ovale—Opening between left and right atria of heart of foetal mammals. 3. Foramen of Monro—A passage linking cerebral cavity with the third ventricle in the vertebrate brain. 4. Foramen of Panizzae—A small opening connecting the two systemic aortae of a crocodile or similar reptile. 5.
The digestive tract and associated accessory organs together constitute the digestive system. The basic structure of digestive tract is not similar in all vertebrates. Stomach is a very specialized portion of the digestive tract. The sac-like muscular enlargement of digestive tract between oesophagus and intestine is called stomach. It acts as temporary storage place of