Several techniques were used to study the morphology of the
salivary apparatus of the cockroach, Nauphoeta cinevea. A
general survey of the ultrastructure was made. The acinar
cells were of two distinct types: peripheral and central cells.
The ducts that these cells give rise to could be classified into
three morphologically distinct areas. The fine structure of the
reservoir ducts was also studied.
Intracellular injections of Procion yellow dye and the use
of lanthanum, as an electron dense marker, showed that there
were many intercalated gap-junctions between the septate
desmosomes of the acinar cells.
The innervation of the apparatus was studied in detail
and it was observed, using techniques of fluorescence histochemistry and electron microscopy, that the salivary nerves,
which arise from the suboesophageal ganglion, branch over the
surface of the acini. The axons associated with the acini were
found to be of two morphologically distinct types, designated
type A and type B. Several histochemical tests indicated that
type A axons contained a catecholamine.
It was attempted to stimulate the salivary nerves. This
resulted in structural changes within peripheral cells and
type A axons. When the salivary nerves were cut several
degenerating axon profiles could be identified in association
with the gland cells. This was not observed when the
stomatogastric nerve was cut.
Finally, enzyme-inhibiting drugs were used to interrupt
the synthetic pathways of catecholamines. These experiments
led to a number of unexpected results including the observation
that some of the actions of these drugs appeared to be postsynaptic.