Description 27th gw

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Telencephalon

Surface of the cerebral hemispheres.


At 25–27 gw, on the medial surface of the occipital lobe, two sulci (calcarine and parietooccipital) were distinguished. Signs of cytoarchitectonic differentiation were evident throughout the investigated area by Nissl staining. Two rows of cells in MZ were detected in the  region of parietooccipital sulcus and in areas located dorsal and rostral to this sulcus, defining the boundaries of the secondary visual field (Godovalova et al., 2024).

Ganglionic eminence (GE, eminentia ventricularis lateralis)

In our study, the maximal volume of the GE in one hemisphere was observed at 20–21 weeks of gestation, consistent with published data. Subsequently, GE volume gradually decreased, indicating involution of the ventral germinal matrix, and this also agrees with the literature. Our findings regarding the decrease in GE width at 26–30 gestational weeks are entirely consistent with data obtained using cranial sonography in the same projection.

Average GE  width - 2,56 mm, volume - 304,79 mm3



Fig.  3-D reconstruction of the ganglionic eminence at gestational week 27

Histogenesis of the subpallial structure

Neostriatum

Total volume of neostriatum 271,36 mm3
Volume of caudate nucleus 102,36 mm3
Volume of putamen 169 mm3