Three-dimensional anatomical structure formed by granule cell layer and pyramidal cell layer in human hippocampus

Area of Science:

• Neuroscience
• Human Anatomy
• Histology

Background:

• The human hippocampus has a segmented pyramidal layer (PL) and an undulated granule cell layer (GL) in the dentate gyrus (DG).
• The relationship between pyramidal hillocks (PHs) and the GL's undulations in the human hippocampus remains unclear.

Purpose of the Study:

• To elucidate the three-dimensional cytoarchitecture of the PL and GL in the human hippocampus.
• To clarify the structural relationships between PHs and GL undulations.

Main Methods:

• Three-dimensional reconstruction of the GL and PL from serial sections of human hippocampus.
• Hematoxylin and eosin staining for histological analysis.

Main Results:

• The GL forms a tube with dorsal opening, exhibiting undulations and digit-like processes, especially medially.
• PHs in the PL form ellipsoidal troughs, with GL protrusions varying in length and position.
• A structural unit comprises a PH trough and associated GL protrusions, forming longitudinal segments.

Conclusions:

• The PH and GL form integrated units that constitute the longitudinal segmental organization of the human hippocampus.
• This study clarifies the complex 3D cytoarchitecture of the human hippocampal formation.