Investigation on the morphologic and morphometric changes in perikaryon and nucleus of spinal neuron during prenatal and postnatal life of male dogs

To study the growth process of perikaryon and nucleus of spinal neurons, 15 domestic male dogs in 5 age groups including 42-day-old fetus, 52-day-old fetus, newborn, 6-month-old and adult dogs were studied. After preparation of animals, the spinal cord was dissected and then the spinal segments were studied by light and electron microscopy. The results of the present study showed that the maximum diameter of perikaryon and nucleus in all age groups belonged to the eighth cervical segment and the minimum diameter of nucleus belonged to the first coccygeal segment in 42-day-old fetus, the seventh thoracic segment in 52-day-old fetus, first coccygeal segment in newborn and the fourth thoracic segment in 6-month-old and adult animals, respectively. The minimum diameter of perikaryon in all age groups belonged to the first coccygeal segment except in 42-day-old fetus, which was related to the fourth thoracic segment.