page_title: Anatomical terms of location
section_title: Axes
hierarchical_section_title: Anatomical terms of location / Introduction / Axes
caption_attribution_description: Composite image of ciliates, showing anteroposterior axes
context_page_description: Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans.
  All vertebrates, including humans, have the same basic body plan: they are strictly bilaterally symmetrical in early embryonic stages and largely bilaterally symmetrical in adulthood. If they are divided down the middle, in other words, they have mirror-image left and right halves. For those reasons, the basic directional terms can be considered to be those used in vertebrates. By extension, the same terms are used for many other invertebrate organisms.
  While the terms are standardized within specific fields of biology, there are unavoidable, sometimes dramatic, differences between some disciplines. For example, differences in terminology remain a problem that to some extent still separates the terminology of human anatomy from the one that is used in the study of various other zoological categories.
context_section_description: The axes of the body are lines drawn about which an organism is roughly symmetrical. To do this, distinct ends of an organism are chosen, and the axis is named according to those directions. An organism that is symmetrical on both sides has three main axes that intersect at right angles. An organism that is round or not symmetrical may have different axes.
caption: Organisms where the ends of the long axis are distinct. (Paramecium caudatum, above, and Stentor roeselii, below.)
exif: {}