Pharynx Atlas Home

The pictures that comprise the Pharynx Atlas are a focal series through the terminal bulb of the pharynx. The worm is lying on its right side, with anterior towards the upper left and posterior towards the lower right. Dorsal is the upper right and ventral is the lower left.
This is the third image in the series. Earlier images start at the leftmost edge of the pharynx and go consecutively deeper, until the last goes through the very rightmost edge. The focal planes are not equally spaced. They were chosen so that all the nuclei in the terminal bulb would be clearly visible in at least one image.

Click on individual pharyngeal cells to identify them.

Pharyngeal Motor Neuron M5

Description: M5 is a pharyngeal motor neuron of unknown function. Its cell body is in left subdorsal posterior terminal bulb. Its processes ramify through all the nerve cords of the terminal bulb, where they synapse on terminal bulb muscles pm6 and pm7. It is the only neuron with visible synapses to terminal bulb muscle. M5 has one known behavioral effect: when it is killed together with the MC motor neurons, pumps become slightly briefer than if MC alone is killed. (See Pharynx section; Albertson and Thomson, 1975; M5 neuron page.)

Identification: M5 is a medium-size neuronal nucleus in the left subdorsal posterior terminal bulb. It is just dorsal and anterior of mc2DL, a big fried egg, and is straight posterior of I6, which is in anterior dorsal terminal bulb. pm5L (another fried egg just anterior and ventral to I6, and straight anterior of mc2DL), I6, M5, and mc2DL form an easily recognized trapezoid.