Premium
THE DEVELOPMENT, STRUCTURE AND COMPOSITION OF THE OPTIC NERVE OF XENOPUS LÆVIS (DAUDIN)
Author(s) -
Gaze R. M.,
Peters A.
Publication year - 1961
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1961.sp001548
Subject(s) - xenopus , toad , anatomy , optic nerve , tectum , biology , electron microscope , central nervous system , neuroscience , midbrain , endocrinology , optics , biochemistry , gene , physics
The optic nerves of tadpoles and adults of the toad Xenopus lævis (Daudin) have been examined with the electron microscope. The total number of nerve fibres was counted and their diameters measured at various stages of development and the relation between glial cells and nerve fibres is described. In tadpoles at late stage 49, the earliest at which consistent visual responses, as determined by an optokinetic drum, were obtained, the first myelinated fibres are found within the nerve. At this stage the tectum is apparently undifferentiated and shows none of the layering of the adult tectum. Previous to this, the nerve is composed entirely of unmyelinated fibres, which in the early stage 49 number about 5000. These increase throughout development, until in the adult nerve about 6000 myelinated and 28,250 unmyelinated fibres are present.