DEVELOPMENTAL ALTERNATIONS IN PROPRIOCEPTIVE AFFERENT PROJECTIONS IN THE MOUSE SPINAL CORD / 解剖学报

ABSTRACT

Objective To observe the developmental changes of projection and termination of proprioceptive afferent fibers in the mouse spinal cord. Methods Parvalbumin (PV) immunohistochemistry was used to label the proprioceptive afferents. Single and dual immunofluorescence histochemistry were used to examine the growth pattern of proprioceptive afferents and their relationships with motoneurons in the spinal ventral horn (VH). The stained sections were observed under a confocal laserscanning microscope. Results PV-like immunoreactive (LI) proprioceptive fibers first appeared in the dorsal column on embryonic (E) day 14, then entered the gray matter on El5 and reached the intermediate gray matter and VH more obviously on E16. The number and intensity of PV-LI proprioceptive afferent fibers and punctata increased in the VH with age and reached a maximum during earlier postnatal (P) period (P0-P7). After P14, the number and intensity of proprioceptive afferents gradually decreased. The proprioceptive terminals seemed to form close relationship with motoneurons from E17. Conclusion The present study indicates that the somatotopic organization of proprioceptive afferents in the spinal cord is established during the late embryonic and early postnatal stages. These results provide evidence for understanding the development of the reflex movements.