Analysis of the prenatal canine brain identifies species-specific and lineage-associated gene programs

Here, we combine gross anatomy, micro-computed tomography, immunohistochemistry, region-resolved bulk RNA sequencing and comparative developmental alignment to characterize the canine forebrain at approximately embryonic days E40, E50 and E60. Across late gestation, the brain expanded rapidly, cortical folding emerged and major forebrain structures became progressively organized.

RNA sequencing of frontal cortex, parietal cortex and medial ganglionic eminence identified distinct regional identities and broad maturation-associated changes. Shared programs emphasized synaptic and neuronal maturation, whereas region-restricted changes included cortical synapse-related and ganglionic-eminence cilium-related terms. Projection onto a human prenatal transcriptional trajectory placed the canine late-gestation samples within an approximate human mid-gestational window.