The study of the development of the spinal cord has a relatively long
history. The spinal cord was singled out as a favorable site when
cytological techniques were first applied to the study of the embryonic
development of the nervous system. Bidder and Kupffer (1857), using the
new procedure of hardening nerve tissue with chromic acid (Hannover
1844), made an investigation of spinal cord development in fetal sheep.
They reported that the cellular central mass of the spinal cord develops
before its fibrous envelope, deducing from this that the fibers of the
white matter of the embryonic spinal cord were outgrowths of cells in
the gray matter. Bidder and Kupffer also noted that in the spinal
ganglia fibers grew out from cells in both directions, peripherally and
centrally. Their report was one of the earliest ontogenetic lines of
evidence in support of the later-formulated neuron doctrine (Waldeyer
1891). The spinal cord re- mained a favorite topic of morphogenetic
studies of the nervous system through- out the last quarter of the
nineteenth century, with seminal contributions made by His (1886, 1889),
von Lenhossek (1889), Retzius (1898), and Ramon y Cajal (1960). Indeed,
the preoccupation with the spinal cord in the early investigations of
neural development had a lasting, and to some extent regrettable,
influence on ideas about the ontogeny of the brain and on the
terminology adopted by anatomists.
