Evolution of Nerve Development in Frogs; pp. 61–73
I. The Development of the Peripheral Nervous System in Discoglossus pictus (Discoglossidae)Schlosser G. · Roth G.
Brain Research Institute, Center for Cognitive Sciences, University of Bremen, Bremen, Germany
The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle de-velopment which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shifts during evolution of PNS development in frogs.
© 1997 S. Karger AG, Basel
Dr. Gerhard Schlosser, Department of Neurosciences, 0201, University of California, San Diego, La Jolla, CA 92093–201 (USA)
Number of Print Pages : 13
Brain, Behavior and Evolution
Vol. 50, No. 2, Year 1997 (Cover Date: 1997)
Journal Editor: Wilczynski, W. (Atlanta, Ga.)
ISSN: 0006–8977 (Print), eISSN: 1421–9743 (Online)
For additional information: http://www.karger.com/BBE