Fig. 5.

Postsynaptic expression of PDE4D within dendritic shafts in ERC layer II. (A–E) in young adult macaque ERC layer II, PDE4D was predominantly concentrated in dendritic shafts and was associated with microtubules oriented in parallel bundles and likely SER tubules (pseudocolored pink), in both horizontal and perpendicular planes. In (A), a fortuitous section showing a dendritic spine emanating from a dendritic shaft, with PDE4D immunolabeling directly in association with microtubules. The dendritic spine receives an axospinous asymmetric glutamatergic-like Type I synapse. (B, D, and E) PDE4D immunolabeling within dendritic shafts was associated with mitochondrial profiles, potentially regulating calcium entry via MAMs, a process regulated by cAMP-PKA signaling. In (D) and (E), dendritic shafts receive axodendritic asymmetric Type I glutamatergic-like synapses; synapses are between black arrows. Color-coded arrowheads point to PDE4D (green) immunoreactivity. Profiles are pseudocolored for clarity. Ax, axon; Den, dendrite; Mit, mitochondria. Scale bars, 200 nm.