Septal apertures in the humerus of normal and experimental rats

Septal apertures of the humerus are rare in wild and domesticated rats but their occurrence is more frequent in females than in males and on the left than on the right side. Septal apertures can be produced experimentally by hypophysectomy due to an extreme reduction of the thickness of the septal wall. Other endocrine ablations, starvation and unilateral front leg paralysis do not produce a sufficient reduction of septal wall thickness to cause septal apertures. Their occurrence is also not correlated with total humeral robusticity. Thus, the manifestations of septal apertures in a non-specialized mammal such as the rat do not differ from those in higher primates.