AIntFIG 2: Transmission electron micrographs (TEMs) of young and old C. elegans intestine, seen in cross-section.

Thin sections in the midbody region show the intestine further posterior from the pharynx than shown in AIntFIG 3.
A. Young adult (1 day) animal shows intestine cytoplasm containing little yolk or other inclusions with a narrow lumen and healthy looking mircovilli. (Image source: N506A [Hall] M673.)
B. The 2-3 day-old adult lumen is fairly narrow though still filled with some mushy bacterial debris and the cytoplasm is filled with lipids and other complex components. (Image source: N903A [Hall] X709.)
C. In this 15-day-old class C animal, the intestine is swollen by many intact bacteria as was seen in AIntFIG 3B. The cytoplasm has shrunken due to the swollen lumen, and is dominated by enlarged clear vacuoles, often coalesced, with reduced amounts of ground substance separating them. (Image source: N807 [Hall] G581.) Note that when one compares the cytoplasm between AIntFIG 2A (and also AIntFIG 3A) with AIntFIG 2B, the contents have changed fairly dramatically, with the first example coming from a probable one day adult, and the second from a probable 2 or 3 day adult. Both examples are filled with highly complex varieties of organelles, but the relative fraction of vesicles containing yolk (large darker filled vesicles) is already dropping.

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