Experiments on the origin of the sheath cells and sympathetic neuroblasts in amphibia

Perineurial Glia

“…In these studies, we conclude that at least a subset of perineurial glia originate within the CNS, although many of the older studies hypothesize that Schwann cells as well as another glial populations are derived from the neural tube (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). The data from these more recent studies do not rule out the possibility that other peripheral glia, including Schwann cells, also originate from precursors in the CNS, and future studies investigating this possibility with modern techniques promise to yield intriguing results.…”

“…Therefore, it is possible that some vertebrate peripheral glia are also CNS derived, and there is significant evidence in the literature to support this hypothesis. Beginning in the early 1900s, anatomists, including Raven, Harrison, Detwiler, and Jones, all performed studies investigating the origin of sheath cells, which we now call Schwann cells (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). Using chick and frog in combination with vital dye labeling and neural crest removal, all of these investigators concluded that most nerve sheath cells were neural crest derived (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987).…”

“…Beginning in the early 1900s, anatomists, including Raven, Harrison, Detwiler, and Jones, all performed studies investigating the origin of sheath cells, which we now call Schwann cells (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). Using chick and frog in combination with vital dye labeling and neural crest removal, all of these investigators concluded that most nerve sheath cells were neural crest derived (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). However, all of them also noted that, even in the absence of the neural crest, some sheath cells were still present along ventral peripheral nerves and that they must have originated within the neural tube (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987).…”

“…Using chick and frog in combination with vital dye labeling and neural crest removal, all of these investigators concluded that most nerve sheath cells were neural crest derived (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). However, all of them also noted that, even in the absence of the neural crest, some sheath cells were still present along ventral peripheral nerves and that they must have originated within the neural tube (Harrison 1906(Harrison , 1924Detwiler 1937;Raven 1937;Lunn et al 1987). One possible explanation for the presence of CNS-derived sheath cells in these studies could be the absence of the neural crest.…”

Neural crest and the origin of ectomesenchyme: Neural fold heterogeneity suggests an alternative hypothesis

“…Ectomesenchyme produces a variety of craniofacial skeletal and connective tissues, whose cellular phenotypes are remarkably distinct from neurogenic and melanogenic derivatives of the neural crest. These derivatives include components of the meningeal sheath covering the central nervous system (Raven, 1936(Raven, , 1937see Weston, 1970;Hall and Hö rstadius, 1988;LeDouarin and Kalcheim, 2000, for classic citations), osteogenic cells of the jaw, palate, and parts of the skull (Chibon, 1969;Johnston, 1966;LeLievre and LeDouarin, 1975;LeLievre, 1978;Noden, 1978;Hall and Tremaine, 1979;Noden, 1988;Smith and Hall, 1990;Morriss-Kay et al, 1993), the corneal stroma (Hay, 1980), the odontoblasts of the dental papilla (Thesleff and Nieminen, 1996), and stromal cells of the thyroid, thymus, and probably other tissues whose differentiation involves interactions with pharyngeal endoderm (Bockman and Kirby, 1984;Weston, 1984). In terrestrial vertebrates, cells that form the vascular septa dividing the pulmonary and systemic outflow of the heart also arise from this mesenchymal population (Kirby et al, 1983;Morriss-Kay et al, 1993), and in aquatic vertebrates, ectomesenchyme produces connective tissue of the dorsal fin (DuShane, 1935;Hö rstadius and Sellmann, 1946;see Hö rstadius, 1950, for summaries).…”