The interthalamic adhesion is absent in 20% of humans

At this morning's brain cutting conference, the question arose as to whether or not the interthalamic adhesion is present in all humans. According to Dr. Bob Struble's memory, and confirmed by my internet search, the interthalamic adhesion (also known as the massa intermedia) is indeed sometimes not present. According to biology-online.org, the massa intermedia is a "variable connection between the two thalamic masses across the third ventricle; absent in about 20% of human brains." Moreover, in my copy of The Ciba Collection of Medical Illustrations (1991), Dr. Frank Netter implies that more than one adhesion can be present. He writes on page 29: "The medial surfaces are joined by a band (or bands) - the interthalmaic adhesion (massa intermedia)." There you have it. Have a good weekend!