ID#: 5230 Description: This micrograph reveals the cephalic alae in the head region the nematode Enterobius vermicularis, or human pinworm.  The time between ingestion of infective eggs to oviposition by the adult females is about 1 mo. The life span of the adults is about 2 mo. Gravid females migrate nocturnally outside the anus, and oviposit while crawling on the skin of the perianal area.  Content Providers(s): CDC Creation Date: 1982  Copyright Restrictions: None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.