Studies in intracranial physiology & surgery : the third circulation, the hypophysis, the gliomas / by Harvey Cushing.

  • Cushing, Harvey, 1869-1939.
Date:
1926
Catalogue details

Licence: In copyright

Credit: Studies in intracranial physiology & surgery : the third circulation, the hypophysis, the gliomas / by Harvey Cushing. Source: Wellcome Collection.

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    Harvey, and his co-workers,57*64 who have shown the futility of patching a dural defect by the transplantation of fat or fascia, as is often advocated ; for if the arachnoidea over the cortex remains intact, the dura will spontaneously re-form without adhesions, whereas should the pia-arachnoid and cortex have been damaged dense adhesions will form and incorporate the dura even though its inner surface had been uninjured. In other words, as Dr. Harvey puts it, ‘ the inner surface of the dura does not act as a limiting membrane in the presence of an attempted repair in the underlying meninges but on the contrary enters intimately into the process ’ ; and he contends that there are not only morpho¬ logical but actually functional differences in the two membranes, one of which merely lines a potential subdural space, whereas the other is a more highly differentiated structure. My own explanation of the difference in the behaviour of the two surfaces to injury would have been that the arachnoid exudes fluid, thereby providing a space which, as we have seen, becomes promptly lined by cells that migrate from the mesenchyme to make a new membrane ; the dura, on the other hand, does not exude fluid, and consequently adhesions form, since there is nothing to keep the surfaces apart when the pia-arachnoid has been damaged. But Dr. Harvey has recently brought forward additional proofs in support of his view.66 He conceived the idea that the cells of the leptomeninges might be derived from the same source as the sheath cells of the peripheral nerves, which arise, as R. G. Harrison had shown, from the embryonic neural crest, whereas the dura itself merely develops from the mesenchyme. Employing Harrison’s methods he removed a bit of the cerebral hemisphere of one amblystoma embryo and transplanted it into the mesenchyme in the region of the fore-limb of