EVOLUTIONAL MORPHOLOGY OF THE UMBILICAL CORD IN THE PERINATAL LIFE TIME IN CALVES

Summary The immediate functional closure of the fetal circulation that is followed by anatomical obliteration of the umbilical structures take place during the first few hours or days of the new borne life and become conjunctively consolidated in the subsequent life time. Little appears to be known in animals regarding the quick functional response to birth changes and the transformative morphology of the umbilical residual structures. The present paper underlines the changes which occur in this anatomical area at the parturition, after the shutting down of the placental circulation in calf. The observation focuses on the morphological ground of the dynamic changes which involve the communication channels like the umbilical ring crossed by extra;abdominal vessels surrounded by the Wharton’s jelly. Birth changes in the fetal circulation make necessary the quickly closure of some pre;existent anatomical communication channels by certain coordinated mechanisms which permit the beginning of an autonomic life. Being a natural defect in the midline of the ventral aponeurosis and the ventral abdominal wall during the fetal life, the umbilical orifice allows the passage of the umbilical cord structures. The nowadays well known pattern of the closure and retraction of the canaliculated structures ; like urachus and the blood vessels is based on the contraction of their muscular walls but can not explain the speed and promptitude of the stint expressed in the whole umbilical cord structure and the ventral abdominal wall closure. However, in veterinary investigated literature there are neither reports focusing on the changes regarding the remnant anatomical structures belonging to the umbilical cord nor the pattern of its involution in neonate calves.