Fig. 4
Organization of the second arm segment of A. kochii. Cross sections. (a) Low magnification view. Toluidine blue. (b, c) Transmission electron microscopy. (b) Overview of the radial nerve cord, water-vascular canal, and arm coelom. (c) High magnification view of the ectoneural neuropil. c—arm coelom; en—ectoneural part of the radial nerve cord; hn—hyponeural part of the radial nerve cord; wvc—water-vascular canal. Dashed lines indicate the arm coelom; dotted lines show the boundaries of the hyponeural part of the radial nerve cord