Fig. 6

Histological details of the central nervous system of Asajirella gelatinosa. A Oral view of the lophophoral base. The cerebral ganglion is located at the anal side of the pharynx and shows several projections with the ganglionic horns projecting into the lophophoral arms and epistomial horns into the epistome. Above the epistome coelom, the ciliated forked canal is shown. B Cross-section through the lophophoral base shows the cerebral ganglion and the intestine. Several bundles of the retractor muscle insert at the peritoneal lining of the ganglion. C Cross section through the distal area of the lophophoral base including two epistomial horns with large lumina. D Cross section through the central area of the cerebral ganglion showing the large size of the ganglionic lumen. Neuronal tissue is located on the anal wall of the ganglion. E Cross-section through the proximal area of the cerebral ganglion showing dense neuronal tissue. The circumoral nerve ring projects orally around the pharynx. cc coelomic cavity, cg cerebral ganglion, ci cilia, con circumoral nerve ring, cw cystid wall, ec epistome coelom, eh epistomial horns, enb epistome neurite bundles, ep epistome, epc epistome canal, fc forked canal, gl ganglion lumen, gh ganglionic horns, int intestine, loc lophophoral concavity, mo mouth opening, ot oral tentacles, ph pharynx, rm retractor muscle, t tentacle, tc tentacle coelom