Lungs Tubercles are nodules that contain caseous necrosis, which form in the lungs as a result of an infection with Mycobacterium tuberculosis in the patients with tuberculosis. Granulomas form in the infected tissue and undergo necrosis in the centre. Tubercles are also known as tuberculous nodules, or tuberculomas. The affected parts develop lesions in the form of small nodules called tubercles, from which the disease gets its name. Ears Around the sixth week of gestation, six swellings of tissue called the hillocks of Hiss arise around the area that will form the ear canal. These eventually coalesce to form the outer ear. Darwin's tubercle is a minor malformation of the junction of the fourth and fifth hillocks of Hiss. It is found in a substantial minority of people and takes the form of a cartilaginous node or bump on the rim of their outer ear, which is thought to be the vestige of a joint that allowed the top part of the ancestral ear to swivel or flop down over the opening to the ear. Genitals The genital tubercle is a small bump that eventually develops into a penis or a clitoris on a human fetus. Brain The septotubercular tract can be found in the human, as well as in the sheep brain. It is found nearby the septohypothalamic tract. Its function to the brain is ambiguous at this point. Also, the tuberculum sellae is found at the base of the skull, which holds the hypophysis. See also Areolar glands, sebaceous glands surrounding the nipple References External links Tubercle at Cactus-Art.biz Human anatomy Animal anatomy Plant morphology