page_title: Ascaris lumbricoides
section_title: Morphology
hierarchical_section_title: Ascaris lumbricoides / Morphology
caption_attribution_description: English: An fertile egg of Ascaris lumbricoides
context_page_description: Ascaris lumbricoides is the "large roundworm" of humans, growing to a length of up to 35 cm. It is one of several species of Ascaris. An ascarid nematode of the phylum Nematoda, it is the most common parasitic worm in humans. This organism is responsible for the disease ascariasis, a type of helminthiasis and one of the group of neglected tropical diseases. An estimated one-sixth of the human population is infected by A. lumbricoides or another roundworm. Ascariasis is prevalent worldwide, especially in tropical and subtropical countries.
  It has been proposed that Ascaris lumbricoides and Ascaris suum are the same species.
context_section_description: Ascaris lumbricoides is characterized by its great size. Males are 2–4 mm (0.08–0.2 in) in diameter and 15–31 cm (5.9–12 in) long. The male's posterior end is curved ventrally and has a bluntly pointed tail. Females are 3–6 mm (0.1–0.2 in) wide and 20–49 cm (7.9–19 in) long. The vulva is located in the anterior end and accounts for about one-third of its body length. Uteri may contain up to 27 million eggs at a time, with 200,000 being laid per day. Fertilized eggs are oval to round in shape and are 45–75 μm (0.0018–0.0030 in) long and 35–50 μm (0.0014–0.0020 in) wide with a thick outer shell. Unfertilized eggs measure 88–94 μm (0.0035–0.0037 in) long and 44 μm (0.0017 in) wide.
caption: Fertile egg as can be seen in a microscope
exif: {"Image ImageDescription": "S", "Image Make": "LG Electronics", "Image Model": "KP570", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS4 Windows", "Image DateTime": "2012:03:12 23:00:27", "Image ExifOffset": "220", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "518", "Thumbnail JPEGInterchangeFormatLength": "3243", "EXIF FNumber": "14/5", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2010:09:15 18:01:59", "EXIF DateTimeDigitized": "2010:09:15 18:01:59", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ApertureValue": "3", "EXIF FocalLength": "71/20", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1000", "EXIF ExifImageLength": "985"}