Emergence and migration of trunk neural crest cells in a snake, the California Kingsnake (Lampropeltis getula californiae)

In this study, we show for the first time ever trunk neural crest migration in a snake by labeling it with DiI and immunofluorescence. As in birds and mammals, we find that early migrating trunk neural crest cells use both a ventromedial pathway and an inter-somitic pathway in the snake. However, unlike birds and mammals, we also observed large numbers of late migrating neural crest cells utilizing the inter-somitic pathway in snake.We found that while trunk neural crest migration in snakes is very similar to that of other amniotes, the inter-somitic pathway is used more extensively by late-migrating trunk neural crest cells in snake.The neural crest is a group of multipotent cells that emerge after an epithelial-to-mesenchymal transition from the dorsal neural tube early after neural tube closure. These cells give rise to a wide variety of neuronal and glial derivatives in the peripheral nervous system, as well as parts of the head skeleton and endocrine organs [1,2]. In jawed, anamniote vertebrates like sharks and teleosts, neural crest cells also give rise to electrosensory organs [3] and fin mesenchyme [4]. The neural crest in the trunk portion of an embryo has been found to follow different migratory pathways in different organisms. In amniotes trunk neural crest cells will follow two main courses: a ventromedial pathway through the rostral part of somites, and a dorsolateral pathway between somites and ectoderm [5]. In amphibians, trunk neural crest follows a dorsal pathway into the fin and a ventral pathway between the neural tube and the caudal portion of the somite [6]. In zebrafish, trunk neural crest predominantly migrates between the neural tube and somites as in amphibians [7,8].The origin of the neural crest was an important event in vertebrate given that it forms most of the craniofacial skeleton [9]. Agnathans (like lampreys) [10,11], teleosts (bony fish) and amphibians clearly possess identifiable cranial neural crest streams that are similar to tho