Skeletal Development of the Vertebral Column in the Miniature Hylid Frog Acris Crepitans, with Comments on Vertebral Anomalies

Abstract

Although the vertebral column of anurans has received much attention in the last 150 years, few detailed studies exist of their skeletal morphogenesis. Herein, the skeletal ontogeny of the vertebral column of the miniature hylid frog Acris crepitans is described on the basis of clear and double-stained, X-rayed, and CT-scanned specimens. The adult axial formula is 1-7-1-1. Vertebral centra are epichordal and procoelous. The neural arches are nonimbricate and there is a medial articulation between the laminae of Presacrals I and II. Free ribs are absent, and the sacral diapophyses have a uniform width or a slight distal expansion. The urostyle is slender, round in cross-section, and about equal in length to the presacral region. Presacral vertebrae are the first to form, developing in a cephalic-to-caudal sequence. Development and growth, however, are decoupled; thus, the initial growth rate is highest in the posterior presacrals and sacrum. In addition, there is a time lag between the formation of the presacral and sacral regions and the postsacral region. Nearly 10% of the specimens examined have vertebral anomalies such as discrete vertebral elements posterior to the sacrum, and about 50% display small, normal variants from the typical vertebral column morphology.

Meeting Name

Annual Meeting of the Society for Integrative and Comparative Biology, SICB (2008: Jan. 2-6, San Antonio, TX)

Department(s)

Biological Sciences

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2008 Oxford Press, All rights reserved.

Publication Date

01 Jan 2008

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