SPINAL CORD – 2
A cross-section reveals that its gray matter occupys the the center of the spinal cord (unlike the brain and cerebellum). The shape of the gray matter in a cross section resembles a butterfly.
The spinal cord is covered by the meninges. However, during the dissection of the organs of the central nervous system, the meninges stay usually attached to the bone surfaces that surround the nervous tissue (bones of the skull, vertebral canal).
The dark matter – highlighted in dark gray – occupies the central region of the spinal cord and is surrounded by the white matter – highlighted in light gray. Depending on the location of the cross-sections of the spinal cord, the gray matter resembles the image of a butterfly.
In the center of the gray matter exists a long and narrow tube that runs inside the entire length of the spinal chord – central canal of the spinal cord or ependymal canal – indicated by a blue circle. The canal contains cerebrospinal fluid. This canal is a remnant of the neural tube cavity formed during the embryonic period.
See a detail of the canal in the lower figure. The canal is lined by a simple ciliated columnar or cuboidal epithelium. The arrows in this figure indicate cilia of the cells of this epithelium.
Spinal cord. Staining: HE. Very small magnification.
Ependymal canal. Staining: HE. Medium magnification.