Postnatal closure of the ductus arteriosus in West African dwarf goats.
Fifteen West African dwarf goats aged between 0 and 42 days were used to study the closure time of the ductus arteriosus using dye injection and histological techniques. The ductus arteriosus appeared haemodynamically patent in kid goats 0 to three days old. There was a progressive contraction of the smooth muscle cells of the wall of the ductus from birth, resulting in the obliteration of the lumen in four and six days at the pulmonary and aortic ends, respectively. This contraction phase was followed by disruption of the luminal endothelium, intimal thickening and necrosis of smooth muscle cells in goats nine to 18 days old. Beyond 21 days there was connective tissue formation resulting in the permanent sealing of the ductal lumen in goats 28 to 33 days old. Although lumina of varying sizes were observed in histological sections of the ductuses of four- to 32-day-old goats, these were haemodynamically insignificant. The results suggest three phases in the closure of the ductus arteriosus of West African dwarf goats which was completed between 28 and 33 days.