RECTAL GLAND OF FRESHWATER STINGRAYS,POTAMOTRYGONSPP. (CHONDRICHTHYES:POTAMOTRYGONIDAE)
Open Access
- 1 June 1978
- journal article
- research article
- Published by University of Chicago Press in The Biological Bulletin
- Vol. 154 (3) , 508-516
- https://doi.org/10.2307/1541076
Abstract
1. Contrary to some reports, a rectal gland is present in strictly freshwater stingrays of South American rivers (Potamotrygon spp.). 2. The gland has the location and histological features of the salt-secreting rectal gland of marine elasmobranchs, but is much reduced in size and number of tubules. 3. Its residual function, if any, is unknown. 4. The rectal gland is associated with prominent myeloid lobes, here designated as rectomyeloid bodies. 5. In the absence of potamotrygonid fossils, the atrophied rectal gland is strong evidence of marine ancestry for the freshwater rays. 6. Both the reduced gland and the loss of urea retention in potamotrygonids are indicative of a long history of freshwater adaptation.This publication has 5 references indexed in Scilit:
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- Studies on electrolyte changes in the lip-shark, Hemiscyllium plagiosum (bennett), with special reference to hormonal influence on the rectal glandComparative Biochemistry and Physiology, 1967
- ANATOMY HISTOLOGY AND HISTOCHEMISTRY OF RECTAL GLAND IN LIP-SHARK HEMISCYLLIUM PLAGIOSUM (BENNETT)1967
- Studies on sodium-potassium-activated adenosinetriphosphatase—XV the rectal gland of the elasmobranchsComparative Biochemistry and Physiology, 1966
- Rectal Glands of Marine and Fresh-Water Sharks: Comparative HistologyScience, 1964