Background: The arterial system of the upper extremities in man shows
drastic developmental changes and many individual variations related t
o interspecific variations in primates. The ontogenetic development in
Tupaia was examined from the viewpoint of comparative embryology. Met
hods: Histological specimens of 39 embryos were observed and reconstru
cted in three dimensions using a computer program. Four adult animals
were dissected and examined with angiography to ascertain the end stag
e of development. Results: At the proximal end of the upper arm the de
ep brachial artery appears first as a concomitant vessel with the radi
al nerve. It becomes reduced in size and is succeeded by the posterior
circumflex humeral artery, which is accompanied initially by the axil
lary nerve and finally by the radial nerve. The main arterial passagew
ay to the fingers consists of the brachial and interosseous arteries d
uring early development. The superficial brachial artery and median ar
tery are formed later, and their connection becomes the main route of
blood supply for the finger arteries up to the adult stage. The ulnar
artery is formed at the end of arterial development to form the ulnar
end of the superficial palmar arch. The superficial antebrachial arter
ies are also recognized. Conclusions: All the arterial elements of the
forelimb in Tupaia are observed in a variety of primates, including m
an, and the characteristics of Tupaia are thought to represent the pri
mitive conditions of the common ancestor of tree shrews and primates.
(C) 1994 Wiley-Liss, Inc.