The Rectal Gland in Relation to the Osmoregulatory Mechanisms of Marine and Freshwater Elasmobranchs

The rectal gland of elasmobranchs secretes large quantities of electrolytes and is of primary importance in the osmoregulatory mechanisms of these animals (Burger and Hess, 1960; Burger, 1962). Analogously, various organs of other vertebrates are also known to be involved in salt secretion (Schmidt-Nielsen, 1965; Bonting, 1970; Bentley, 1971). In general, active ion transport is the basis of this phenomenon; in any case, it requires the presence of structural devices, morphologically and chemically well defined, and of metabolic capabilities which, taken singly, are not specific, but collectively are consistent with active ion transport and salt secretion

Aspetti della ghiandola rettale e della regolazione osmoticain Selaci marini e d\u27 acqua dolce

In continuazione di ricerche giil pubblicate (GERZELI G., 1967 - 1st. Lombardo Rend. Sc., BIOI: 117 ; GERZELI F. e DE STEFANO G. F., 1968 - Cony. Soc. Ital. Anat.) l\u27indagine istomorfologica e istochimica sulla ghiandola rettale c stata estes a ad altre specie, integrandola con alcuni dati ehimici su costituenti plasmatici. Sinora sono state esaminate Ie seguenti specie: Scylliorhinus stellaris, Galeus melastomus, Torpedo marmorata, Raja asterias (del Mar Tirreno); Galeorhinus zyopterus (dell\u27Oceano Pacifico orientale) ; Carcharhinus leucas (del Mar dei Caraibi e del Lago di Nicaragua) ; Pristis perotteti (del Lago di Nicaragua) ; Potamotrygon brachiurus (del Rio Uuruguay)