Formirovanie pozvonochnogo kanala v ehmbriogeneze cheloveka

Abstract

In the study, 29 totally cleared and double-stained human embryos of 7-12 weeks of gestational age and 33series of histological sections of 7-70 mm CRL human embryos were used. At the 5th week of gestation, the vertebrae are presented by mesenchymal condensations around the notochord. In 7 week embryos, separate centers of chondrification are identified in the vertebral primordia. At the end of the embryonic period (8th week of development) due to the fusion of the centers of chondrification, the vertebral primordia are presented by whole cartilaginous structures having a centrum located in front of the spinal cord and two neural processes that span it from two sides. The body of the future vertebrae is located on the ventral side of the spinal cord, the anteroposterior size of which is approximately twice as large as the similar size of the cartilaginous primordium of vertebral body. The neural processes are directed dorsally and cover only 3/4 of the circumference of the spinal cord from both sides. As a result, the vertebral foramen remains open behind and there is no spinous process. The neural arches of all thoracic and upper lumbar vertebrae fuse in fetuses of the 10th week of gestation. At the 10th week of gestation, the centers of ossification appear in the neural processes of C2-Th8. The primary centers of ossification in the ribs appear from the 8th week of embryogenesis. It is established that the fusion of the neural processes behind the spinal cord begins with the lower cervical - upper thoracic vertebrae and then the process spreads in the cranial and caudal directions. Simultaneously with the fusion of the neural processes, a spinous process of the vertebrae is formed. The formation of the spinal canal is completed in 12-week human fetuses. At all stages of development of the vertebral primordia, their close interaction with the notochord is traced. Notochord plays an important role in the morphogenesis of axial structures. The congenital neural tube defect (anencephaly) is combined with the spina bifida and fusion of adjacent vertebral arches.