Anatomy of a worm

What is this picture?

This is a picture of a newly-hatched C. elegans larva that carries a gene that causes expression of green fluorescent protein (GFP) in the worm's cells. GFP is a protein that is fluorescent when exposed to ultraviolet light, and this worm was photographed through an epifluorescence microscope.

The worm's nose is pointing to the left and its tail curls around on the right. This is a highly-magnified photograph, as the total length of the worm in this picture is about a fifth of a millimeter (200 micrometers).

The muscular feeding structure called the pharynx can be seen, as can the two germline precursor cells and their associated somatic gonad precursor cells. Also, neurons and neuoblasts can be seen along the ventral surface of the worm, and the dense region of worm axons, called the nerve ring (the worm "brain") can be seen.

The transgene in this animal expresses the CED-10 Rac GTPase protein fused to GFP, so where GFP is seen, the CED-10 GTPase is there as well. CED-10 is associated with the plasma membrane, and the plasma membrane definitions of the neurons and neuroblasts are obvious in the micrograph.