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The cerebral aqueduct is roughly circular in transverse section, and measures 1-2 mm in diameter. [3] It is 15 mm long and is commonly subdivided into a pars anterior antrum, and pars posterior. [ 2 ]
Stimulation of the periaqueductal gray matter of the midbrain activates enkephalin-releasing neurons that project to the raphe nuclei in the brainstem. 5-HT released from the raphe nuclei descends to the dorsal horn of the spinal cord where it forms excitatory connections with the inhibitory interneurons located in Laminae II (aka the substantia gelatinosa).
Neurobiologists have often had great difficulty distinguishing the VTA in humans and other primate brains from the substantia nigra (SN) and surrounding nuclei. Originally, the ventral tegmental area was designated as a ‘nucleus’, but over time ‘area’ became the more appropriate term used because of the heterogeneous cytoarchitectonic features of the region and the lack of clear ...
Hence, what is technically a transverse (orthogonal) section with respect to the body length axis of a rat (dividing anterior from posterior) may often be referred to in rat neuroanatomical coordinates as a coronal section, and likewise a coronal section with respect to the body (i.e. dividing ventral from dorsal) in a rat brain is referred to ...
A series of transverse sections through an embryo of the dog. (After Bonnet.) Section I is the most anterior. In V the neural plate is spread out nearly flat. The series shows the uprising of the neural folds to form the neural canal. a. Aortæ. c. Intermediate cell mass. ect. Ectoderm. ent. Entoderm. h, h. Rudiments of endothelial heart tubes.
The section of the pia mater enveloping the brain is known as the cranial pia mater. It is anchored to the brain by the processes of astrocytes , which are glial cells responsible for many functions, including maintenance of the extracellular space.
The commissural fibers or transverse fibers are axons that connect the two hemispheres of the brain. Huge numbers of commissural fibers make up the commissural tracts in the brain, the largest of which is the corpus callosum .
A section plane orthogonal to the axis of any elongated form in principle is held to be transverse (e.g., a transverse section of a finger or of the vertebral column); if there is no length axis, there is no way to define such sections, or there are infinite possibilities.