Embryology of the walls of the lateral sellar compartment: apropos of a continuous series of 39 embryos and fetuses representing the first six months of intra-uterine life.

The aim of this study was a continuous and rather exhaustive description of the embryological development of the lateral sellar compartment. The histological sections of 39 embryos and fetuses were studied, and represent the first six months of intra-uterine life. The embryological period showed the organization of the content of the compartment. The medial and lateral walls appeared during the 15th week of amenorrhoea, and did not modify later. The medial wall was constituted in its rostral part by the hypophyseal lodge and in its caudal part by the periosteum of the sphenoid bone. Two layers formed the lateral wall: the superficial layer was an expansion of the dura mater that surrounded the oculomotor nerves along their course to the superior orbital fissure; the deep layer was weaker, and surrounded and joined the nerves together. The results of this study advocate the evolution of the nomenclature of this region, as the term "inter-periosto-dural space" would better reflect the real pattern of the lateral sellar compartment. Furthermore, the presence of a communication between the two lateral sellar compartments has led to a discussion of the previous hypothesis about the development of the lateral sellar compartment. The venous network was located on both the medial and lateral sides of the internal carotid artery, but expanded in the lateral wall of the lateral sellar compartment. That is of interest to surgeons and radiologists because it could explain some hemorrhagic complications.