2. The lamprey epithalamus is far more asymmetric than the others. It looks as though the asymmetry diminished during the course of evolution. This is not what I expected.
1. I wasn't able to copy the figures, but you can see them by clicking on the link.
Cross references: Amphioxus Asymmetry Human AsymmetryMy comments:
Asymmetry in the epithalamus ... (Goog)
The habenula in the lamprey shows a remarkable asymmetry in both size and neuronal organisation. This phenomenon is already detected at larval stages but becomes more substantial after metamorphosis. While neurons on the left are restricted to the periventricular area, in the right hypertrophied habenula they are also arranged in distinct superficial cell layers. Asymmetry also extends to efferents from the habenula that course ipsilaterally in the habenulo-interpeduncular tract or fasciculus retroflexus, the right tract appearing muchlarger than the left tract.
Afferent and efferent connections of the parapineal organ in lampreys: a tract tracing and immunocytochemical study.
Cholinergic and GABAergic neuronal elements in the pineal organ of lampreys, and tract-tracing observations of differential connections of pinealofugal neurons.
Morphology of the pineal complex of the anadromous sea lamprey, Petromyzon marinus L.
Evolutionary conservation of the habenular nuclei and their circuitry controlling the dopamine and 5-hydroxytryptophan (5-HT) systems. - Free PMC Article -