Talk:Paper - Defective development of the septum pellucidum (1932)

432 Anatomical Notes

DEFECTIVE DEVELOPMENT OF THE SEPTUM PELLUCIDUM

By R. KRISHNA RAU, F.R.C.S., L.R.C.P. (EpIN.), anD D. SIVASUBRAHMANIAM, M.R.C.S. (Enc.), L.R.C.P. (LOND.)

Department of Anatomy, Medical College, Vizagapatam, India

Durine the course of the dissections of the brain by the senior second-year students in the sixth terminal trimester of their Anatomy course corresponding to the winter session of this year, our attention was drawn by a batch of students to the abnor‘mality described hereunder. ,

After exposing the corpus callosum from above and dividing it transversely at about its middle it was noticed that the usual septum intervening between the corpus callosum and the fornix (F'0.) was absent. There was, however, at the forepart of

Fig. 1. Diagrammatic representation of the defective development of the septum pellucidum.

the interval the rudiments of a partition (S.P.) showing a concave posterior free margin. A section through the attenuated partition revealed the absence of any cavity in its interior, as it comprised a solid core of white matter surrounded by a thin layer of grey matter. This structure was adherent to the subjacent fornix. The normal septum described under the name of the septum pellucidum was found to be defective and confined to the forepart of the interval between the two lateral ventricles (see fig. 1).

This partition was about 4 in. antero-posteriorly and 3 in. from above downwards, having a trapezoid outline with its broader upper convex margin attached to the under surface of genu (Cre.) of the corpus callosum, its anterior concave Anatomical Notes 433

margin to the rostrum (Ro.) becoming continuous inferiorly with the lamina rostralis, below and behind to the anterior pillar of the fornix. The posterior margin, however, was blunt, crescentic and free. On making a sagittal section of the cerebrum the anterior commissure (4.C.) could be made out in its usual position. The condition was not pathological, as evidenced by the appearance of the parts. The principal features of interest are: . The septum, though present, is defective. It is solid and unilaminar. . The absence of the cavity of the septum pellucidum. The free communication between the two lateral ventricles. . The foramina of Munro are smaller than normal. The other structures constituting the Rhinencephalon are normally developed. We have ventured to submit this article for publication as the abnormality described above is a rare one and as there is hardly any reference to it in the available works of reference here.

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