 So, now from the median eminence of tuberosinarium in the flow of the third ventricle, let's move on to the second circumventricular organ. The second circumventricular organ is located in this sheet of gray matter that you see here. This is known as the lamina terminalis. The lamina terminalis is a very important sheet of gray matter which extends from the rostrum of the corpus callosum and merges with the anterior surface of the optic chiasma here. This lamina terminalis forms the anterior wall of the third ventricle and it is formation of the lamina terminalis is essential for the formation of the cerebral hemisphere. Now, within this lamina terminalis there is a very important circumventricular organ which is known as the organum vasculosum of lamina terminalis, OVLT. In simple terms it is also referred to as the vascular organ of lamina terminalis. Now, how does this function? This functions as an osmoreceptor. Therefore, it monitors the osmolarity of the serum. The normal osmolarity of the serum is 280 to 300 milliosmoles per kg body water. So, when the osmolarity of the serum rises it sends its impulses to the suprapoptic nucleus which is located here and it causes it to release anti-diuretic hormone ADH. So, therefore, this lamina terminalis organum vasculosum acts as a osmoreceptor. Additionally, this OVLT also provides a vascular outlet for the secretions by the pre-optic nucleus namely luteinizing hormone, release hormone. The pre-optic nucleus is located right here and it also acts as a vascular outlet for a small nucleus located here called the suprachiasmatic nucleus which releases, which apart from stimulating the release of melatonin also releases somatostatin and this is also released via the vascular outlet provided by the organum vasculosum of the lamina terminalis.