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[Ascaris lumbricoides]

Adults of Ascaris lumbricoides are large roundworms.  Females measure 20-35 cm long with a straightened tail; males are smaller at 15-31 cm and tend to have a curved tail.  Adults of both sexes possess three 'lips' at the anterior end of the body.

A	B

A: Adult female A. lumbricoides.
B: Adult female A. lumbricoides.  Image courtesy of the Orange County Public Health Laboratory, Santa Ana, CA.

C	D

C: Close-up of the anterior end of an adult A. lumbricoides.  Note the three 'lips.'  Image courtesy of the Orange County Public Health Laboratory, Santa Ana, CA.
D: Posterior end of a male A. lumbricoides, showing the curled tail.

E	F

E: Cross-section of an adult female A. lumbricoides, stained with hematoxylin and eosin (H&E).  Note the presence of the prominent muscle cells (MU), gravid uterus (UT), intestine (IN) and coiled ovary (OV).
F: Cross-section of the cuticle of an adult A. lumbricoides, stained with H&E.  Shown here are the cuticle (CU), and immediately below the cuticle, the thin hypodermis (HY).  Also shown are the prominent muscle cells (MU) and one of the lateral chords (LC).