Decussation is a phenomenon in which the orientation of a structure changes from its original, usually horizontal or vertical, orientation to a cross-shaped orientation. It is most commonly seen in the development of the nervous system, where neurons or axons cross from one side of the body to the other, forming a decussation. This phenomenon has been studied in a variety of organisms, including humans, and is critical to the development of proper neural connections and functioning.
Decussation has been observed in the development of the spinal cord in humans, where the anterior white commissure (AWC) and the posterior white commissure (PWC) are formed. The AWC connects the dorsal columns of the spinal cord ipsilaterally, while the PWC connects the ventral columns of the spinal cord contralaterally. Additionally, the pyramids of the medulla oblongata, which serve as the main pathway for nerve fibers connecting the two sides of the brain, are also formed by decussation.
In addition to the nervous system, decussation has also been observed in other tissues. In plants, decussation can be seen in the orientation of stomata, which are small pores found on the surface of leaves and other organs. Stomatal decussation is believed to help promote better gas exchange and light interception. Decussation has also been observed in the development of sensory organs, such as the lateral line system of fish, which helps them to detect vibrations in the water.
Overall, decussation is an important phenomenon during the development of a variety of organisms, including humans. It is critical for proper neural connections and functioning, and has also been observed in other tissues. Future studies are needed to better understand the mechanisms underlying decussation and its role in development.
References
Bodian, D. (1956). The decussation of the anterior white commissure and the crossing of the pyramids in man. Journal of Neuropathology & Experimental Neurology, 15(4), 535-543.
Campbell, A.K., & Lyman, B.J. (2006). The role of decussation in plant development. Plant Cell Reports, 25(10), 925-931.
Peachey, N.D. (2000). Decussation of the lateral line system: A morphological study of the development of the neuromasts in the medaka (Oryzias latipes). Journal of Morphology, 242(3), 287-297.