The fate of the arachnoid villi in humans.

Villi arachnoidales undergoes in the course of life changes in relation to the skull bones and sinuses. Our aim was to determine the relations of the villi arachnoidales to the skull bone and/or sinuses from the neonatal period to adults. The investigations were performed on collection of 50 disarticulated macerated skull bones from the new-born to 30 years of age and on 20 skulls from individuals in the life period from 30 to 80 years of age. Villi arachnoidales produced imprints on the skull bones in the shape of holes and/or furrows corresponding to different shape of the villi arachnoidales. These imprints appeared very early in the period when the bony sprouts of the large skull bones received a thin covering of compact bone, the future lamina vitrea. At that time villi arachnoidales had no connection with the dural sinuses but with the diploe and with the diploic veins. By agglomeration of the villi in larger and large formations, granula meningea, Pacchionian granulations, the contact to sinuses was realized by means of short channels. The structural changes of villi arachnoidales may produce thrombophlebitis and hydrocephalus externus, especially in children. The fate and the relations of the villi arachnoidales are therefore of great importance for neurologist, neurosurgeon and otorhinolaryngologist.