The morphology of the pineal region in teleosts / Robert J. Terry.

  • Terry, Robert J. (Robert James), 1871-1966.
Date:
[1910]
Catalogue details

Licence: In copyright

Credit: The morphology of the pineal region in teleosts / Robert J. Terry. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    ependymal epithelium which appears to consist of secretfng cells, and Herrick (’91) describes the pouch of the diatela as possesed of a wall composed of a single row of cells with long cilia or flagella. It appears, therefore, that in these ganoids the epithelium of the arch is especially modified and lines a great evagination of the diencephalic roof. Regarding the elasmobranchs, Minot (’01) says “ the post-velar arch remains small, hence the velum seems to arise later very close to the mouth of the epiphysis.” The connection of the smaller epiphyseal bud with the post- velar arch by forward shifting brings up the question of its possible relationship with those large outgrowths of this region which have been observed by Schauinsland (SeeKupffer, ’06) inCallorhynchus, by Gierse (’04) in Cyclothone, and by Handrick (See Studnicka, ’05) in Argyropelecus. Commenting on the latter, Studnicka, (’05) says: “Der Fall ist sehr wichtig, da er zeigt, dass der de norma breitere Dorsalsack unter TJmstanden sich in ein enges schlauchformiges Gebilde verwandeln kann. Dieselbe Er- scheinung kann man bekanntlich auch beiderParaphysebeobach- ten; auch diese tritt einmal als ein enger Schlauch, ein anderes Mai wieder in der Gestalt eines breiten Sackes (Paraphyseal - bogen—Sedgwick Minot) auf.” Velum Transversum The velum transversum of the teleosts, according to the current descriptions, consists of a simple transverse fold of the fore-brain roof, having smooth surfaces and a free ventral margin. Rabl- Riickhard (’82) regards the velum as the starting point, phylo- genetically, of the choroid plexus, although he found no differen- tiation in this direction in the bony fishes. In them this organ seems to be less advanced in its development than it is among the selachians, where it has been shown that projections are formed on either side which are regarded by Minot (’01) as the anlages of the choroid plexuses of the lateral ventricles. In Acanthias a superficial coat appears upon the ependyma of the anterior surface of the velum, the nature of which is uncertain, but as