![](/drem/stage18/labels2/S77L.gif)
![cerebral aqueduct (mesencoel), intermediate zone, isthmus of metencephalon, marginal zone, rhombencoel (fourth ventricle), trochlear nerve (CN IV), ventricular zone](/drem/stage18/Z0/S77N.jpg)
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Carnegie Embryo #4430 | Location: 2-39
Keywords: cerebral aqueduct (mesencoel), intermediate zone, isthmus of metencephalon, marginal zone, rhombencoel (fourth ventricle), trochlear nerve (CN IV), ventricular zone
Source: The Virtual Human Embryo.