Terminology for Morphology and Cell Types

  • Richard D. Campbell
  • Hans R. Bode


Hydra exist as polyps, i.e., as sedentary forms of coelenterates. A single animal has the form of a tube, about 5–20 mm long and 0.3–1.0 mm wide, bearing a whorl of hollow tentacles near one end. Animals undergoing asexual reproduction produce buds, which arise as evaginations of the body wall. The body wall consists of two concentric epithelia, the ectoderm and endoderm, separated by a common acellular basement membrane, the mesolamella or mesoglea. This trilaminar structure extends throughout the entire body column tentacles and buds. The ectoderm* (or epidermis) faces the environment, whereas the endoderm (or gastrodermis) lines the hollow cavity called the gastric cavity (coelentron, gut). In describing the morphology of hydra, the adjectives apical (or distal) and basal (or proximal) refer to the directions toward the tentacles and base, respectively.


Interstitial Cell Body Wall Mucous Cell Gastric Cavity Basal Disk 
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  1. This article has not attempted to trace the origins of each terni. The article cited below offers additional terminology regarding nerve cells of hydra.)Google Scholar
  2. Tardent, P., and C. Weber, 1976. A qualitative and quantitative inventory of nervous cells in Hydra attentuata Pall. In: Coelenterate Ecology and Behavior ( G. O. Mackie, ed.), Plenum Press, New York, pp. 501–512.Google Scholar

Copyright information

© Springer Science+Business Media New York 1983

Authors and Affiliations

  • Richard D. Campbell
    • 1
  • Hans R. Bode
    • 2
  1. 1.Department of Developmental and Cell BiologyUniversity of CaliforniaIrvineUSA
  2. 2.Developmental Biology Center and Department of Developmental and Cell BiologyUniversity of CaliforniaIrvineUSA

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