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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    Paraphysis. Velar epithelium extends forward toward thepara- physeal region where there is to be seen a slight transverse fold of the brain-roof. This fold, which appears to be the remains of the paraphysis, forms the anterior end of a median longitudinal groove of the tela, evident in transverse sections. The groove is the beginning of a deep median invagination which in the adult toad-fish separates two diverticula of the caudal end of the telen- cephalic ventricle. Adult Opsanus Epiphysis. The fully developed epiphysis presents a form not uncommon among the teleosts (fig. 17). It consists of an oval end-vesicle terminating a long slender stalk, the whole structure being directed cephalad in the median plane and suspended in the meninges betw^een the fore-brain tela and the cranial roof. The stalk, which is slightly fusiform, measures 6 mm. in length and 0.08 mm. in its greatest diameter. The end-vesicle measures 0.6 mm. in length and 0.38 mm. in greatest breadth. There is no angle between the stalk and vesicle but a gentle curve extends throughout the length of the organ. The cavity, present in both stalk and vesicle, does not communicate with the ventricle. It is traversed by protoplasmic processes forming a wide mesh-work from wall to wall. An artery and vein are associated with the epiphysis throughout its whole extent. In the connective tissue along these vessels and around the distal half of the organ black pigment is present in considerable amount. The commissural canal of the lateral line system is now far anterior to the end of the epiphysis and there seems to be no further relation between these organs. A parietal foramen or fossa of the osseous cranial roof is not present. Superior Commissure. There is no change in the structure and relations of this commissure from what was last observed. Posterior Commissure. The two divisions of the posterior commissure are still recognizable; the intervening connective tissue septum now is less distinct. The anterior division contains some longitudinal fibers which extend in a thin layer around the base of the epiphyseal stalk and on to the intermediate tubercles.