Intraepithelial Flagella in the Medusa of Aurelia Aurita (L.)

Each superficial cell of the flagellated neuroepithelium of the subumbrellar pit of the medusa of Aurelia aurita sends out a basal neurite which turns through one right angle to join other neurites in a well aligned neurite layer next to the mesoglea. In with the neurites are many flagella whose cells of origin are submerged neuroepithelial cells. Because both neurites and flagella are the same diameter and because the flagellar microtubules tend to become separated in such a way as to resemble neurotubules, it was suspected that perhaps flagella could transform into neurites along their course. The evidence was weighed and found wanting mainly because the flagellar origin is blocked by a diaphragm and constriction of the plasma membrane thus preventing the egress of soma-produced granular vesicles and mitochondria which are cytoplasmic features confined to neurites.