Microscopy

A

A: Eggs of Toxocara canis.  These eggs are passed in dog, especially puppies', feces.  Humans infected with Toxocara do not produce or excrete eggs, and therefore eggs are not a diagnostic finding in human toxocariasis.  The egg to the left is fertilized but not yet embryonated, while the egg to the right contains a well developed larva.  The latter egg would be infective if ingested by a human (frequently, a child).