On some aspects of schwann-sheath development and the possible role of their desmosome-like structures.

An investigation was made of ventral and dorsal spinal roots (L7 and S1) in the postnatal life of the rabbit. The development of the Schwann sheath of the nerve fibers was studied and correlated with the distribution and morphological characteristics of the desmosome-like structures connected with them. The association of these structures with constituents of the endoplasmic granular and smooth-surfaced reticulum of the Schwann cell is pointed out. The possibility is discussed of a direct relationship between the inner mesaxons, as well as along the length of the peripheral myelin lamellae. In addition, it is suggested that in some cases already existing membrane formations of the adjacent cytoplasm become attached to the developing Schwann sheaths, which results in branching mesaxons or "poli-mesaxonal" nerve fibers.