Dev Biol 105: 102-14 (1984)
The genesis and differentiation of neurons in a frog parasympathetic ganglion.
R. D. Heathcote & P. B. Sargent
The cellular mechanisms that underlie formation of an autonomic ganglion have
been investigated by studying the formation of the cardiac ganglion of the
frog. Analysis of the genesis of neurons with [3H]thymidine autoradiography
revealed that neuronal precursors do not divide via a "stem cell lineage" but
rather divide exponentially, such that both daughter cells either re-enter the
mitotic cycle or differentiate. Neurogenesis in this autonomic ganglion is
prolonged, beginning during the second day after fertilization and continuing
for at least 2 weeks. The use of acetylcholinesterase (AChE) as a neuronal
marker showed that differentiated neurons start condensing in their target 1.5
days after the first neurons are born. Neurons accumulate, concomitant with
neurogenesis, at a constant rate of approximately six neurons per day.
Transplantation and organ culture demonstrated that immature neurons are
present well before definitive expression of the mature phenotype and that
their initial expression does not depend upon maintained contact by
preganglionic axons.