Groove in lateral wall of third ventricle, marking the boundary between the thalamus

Thalamus

The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

 and hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

. The upper and lower portions of the lateral wall of the third ventricle

Third ventricle

The third ventricle is one of four connected fluid-filled cavities comprising the ventricular system within the human brain. It is a median cleft between the two thalami, and is filled with cerebrospinal fluid ....

 correspond to the alar lamina and basal lamina

Basal lamina

The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often confused with the basement membrane, and sometimes used inconsistently in the literature, see below....

 respectively of the lateral wall of the fore-brain vesicle

Vesicle (biology)

A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...

 and are separated from each other by a furrow, the hypothalamic sulcus (sulcus of Monro), which extends from the interventricular foramen to the cerebral aqueduct

Cerebral aqueduct

The mesencephalic duct, also known as the aqueductus mesencephali, aqueduct of Sylvius or the cerebral aqueduct, contains cerebrospinal fluid , is within the mesencephalon and connects the third ventricle in the diencephalon to the fourth ventricle in the mesencephalon, which is between the pons...

.