A SYSTEMIC SECONDARY VESSEL SYSTEM IS PRESENT IN THE TELEOST FISH TANDANUS-TANDANUS AND ABSENT IN THE ELASMOBRANCHS CARCHARHINUS-MELANOPTERUS AND RHINOBUTOS-TYPUS AND IN THE DIPNOAN NEOCERATODUS-FORSTERI
Lk. Chopin et al., A SYSTEMIC SECONDARY VESSEL SYSTEM IS PRESENT IN THE TELEOST FISH TANDANUS-TANDANUS AND ABSENT IN THE ELASMOBRANCHS CARCHARHINUS-MELANOPTERUS AND RHINOBUTOS-TYPUS AND IN THE DIPNOAN NEOCERATODUS-FORSTERI, Journal of zoology, 246, 1998, pp. 105-110
A system of secondary vessels emerging from the primary vessels as num
erous coiled capillaries has been described in numerous teleost and ho
lost fishes. The systemic secondary vessels of the teleost Tandanus ta
ndanus are typical of this system and are described in this study. The
existence of a secondary vessel system has been postulated in the ela
smobranch group. No secondary vessel origins, as seen in the teleosts,
are present in the elasmobranchs Rhinobatos typus and Carcharhinus me
lanopterus. Vessels with a similar distribution to secondary arteries
are observed but these are venous rather than arterial in nature and d
o not connect with the primary arteries. Like the secondary veins in t
eleosts, the cutaneous veins in R. typus contain blood with a low haem
atocrit. There is no morphological evidence for a secondary vessel sys
tem in the dipnoan Neoceratodus forsteri.