The diploic vascular channels

Gizéh diploic veinsThe diploic channels are placed between the vault cortical layers (external and internal). The calvarial diploe contains large and valveless diploic veins interconnected through a complex network of microscopic channels. We have now published a procedure for segmentation of diploic channels and localization of the main vessel pathways by reducing the noise of the cancellous bone. We also provide quantitative description of the diploic vessel variation in modern humans and three Neanderthals. One modern human was reformatted at three different resolutions namely high, medium and low, to estimate the effect of the pixel resolution on the final anatomical rendering. The use of computed tomography at high resolution can hamper semi-automatic segmentation of the diploic channels. Optimal resolution should be sufficient to reveal the channels without increasing noise associated with the trabecular structure. We have found that modern humans present a remarkable variation of diploic channels in their morphological patterns, being the parietal area the most vascularized. There is a correlation in the degree of vascularization of the frontal, parietal, and occipital bone, and no asymmetries can be apparently detected. The three Neanderthals analyzed in the study also display a parietal vascular network, but less developed than modern human, suggesting these vessels may be involved in evolutionary changes. The diploic network is commonly connected with the meningeal artery at the temporal fossa, with the emissary veins at the occipital bone, and with the venous sinuses at the parieto-occipital areas. The brain and braincase of our specie are characterized by larger parietal areas, and changes in the vascular organization can be associated with thermoregulation and heat management. In this sense future research may help us to understand the possible involvement of the diploic veins in brain thermoregulation. The study of diploic channels may be relevant in anthropology, medicine, paleontology, and forensic sciences.

Gizéh Rangel de Lázaro

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3 responses to “The diploic vascular channels

  • O. García Gil

    Congratulation on this interesting methodological approach. The diploic vessels seem to be part of a very complex network and your results bring new insights into the interpretation of the different vascular elements and their connections. Their direct relation with brain and other cranial structures show the important implications that would have in terms of development, thermoregulation or evolutionary implications.

  • gizehrangeldelazaro

    Thank you so much for your comments!
    As was pointed out in our paper, the diploic channels are isolated inside the cranial tables, protected from post depositional process; however their position has limited, until the advent of computed tomography, the opportunity to analyze its anatomy, variations and functions. In the article we published this week, we presented a segmentation procedure for diploic channels using CT; as well as a quantitative description of their variation in modern humans and Neanderthals. In the sample analyzed we were able to observe a large morphological variation of diploic channels. Also, we noted that diploic veins seem to be more developed in humans than in Neanderthals, indicating a relevant role in human evolution.
    We also found remarkable your preliminary approach to the histological variations of the vault bones in individuals of different ages. As you can see in our blog, last week I published a post about your paper. It will be interesting to see your results on larger samples. Let’s keep in touch, and if you have any comments, please do not hesitate to contact us.

  • Precuneus and chimps | paleoneurology

    […] space, time, and  social perception. It is also worth noting that parietal lobes are particularly vascularized in our species, and the precuneus is a high-metabolic and heat-accumulating element. This may be […]

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