Olfaction is an important and primitive sense. As its importance
has changed with evolution, anatomic adjustments have occurred
in its structure and vasculature. Primates are a family of
vertebrates that have had to develop their visual system to
adapt to the arboreal environment and have evolved from a
macrosmatic to a microsmatic species as the optic system has
enlarged. This has resulted in anatomic changes of a small but
critical area at the base of the brain. This paper describes
the three-dimensional vascular anatomy of the olfactory organ
of the Japanese monkey (Macaca fuscata fuscata). This
is best understood by dividing the organ into three parts: the
olfactory tract, olfactory bulb, and olfactory nerves in the
nasal mucosa. The bulb can be partitioned into an outer or cortical
part and inner or medullary part. The vasculature and tissue
were examined grossly and with light microscopy and scanning
electron microscopy of vascular corrosion casts. The olfactory
tract and bulb were supplied by an arteriole from the anterior
cerebral artery on each side. The tract was supplied by capillaries
running spirally with a coarse network. At the olfactory bulb,
the arteriole ramified into the intracortical and medullary
branches that formed capillary networks. The bulbar intracortical
capillaries were divided into two layers with different densities
and vascular patterns. The capillaries of the superficial layer
had a ladder-like pattern. The branches that ran into the medulla
of the olfactory bulb were more widely spaced. Twigs from the
posterior ethmoidal artery ran along the nerve fiber and formed
intra- and extrafascicular networks. Each region of the olfactory
organ had characteristic three-dimensional vascular patterns
that were related to their cellular architecture.
