Histological Aspects of the Dural Crossing of Arteries to the Brain in the Fetus

This study aims to determine the histological evolution of the relationship between the dura mater and the walls of the arteries with the encephalic destination in fetuses of different ages.

Methods and Materials/Patients: 

We conducted a prospective descriptive study over 4 months. It included eight fetuses aged between 24 and 34 weeks of amenorrhea obtained after informed consent from the parents. Four fetuses were less than 30 weeks old and four were more than 30 weeks old. After the previously formalized anatomical dissection of the fetal skull base, partial pairs of the internal carotid and vertebral arteries were removed at the level of the dural crossing. Samples were fixed with 10% formalin and embedded in paraffin before routine histochemical (hematoxylin-eosin) and immunohistochemical (matrix metalloproteinase 7 [MMP7]) staining.

We observed a "separation zone" between the dura mater and the arterial wall that is complete in fetuses between 24 and 29 weeks gestation. This cleavage zone disappeared in fetuses of 30 weeks gestation and more. This dural-arterial contact, observed from this age onwards, bears witness to a progressive arterial "invasion" by the dura mater, to reach the aspect observed in adults, characterized by the penetration of dural fibers into the arterial wall. 

The duro-arterial relationship at the intersection level is a dynamic phenomenon that has been going on since the antenatal period.