Growth plate formation and development in alligator and mouse metapodials: Evolutionary and functional implications

Title

Growth plate formation and development in alligator and mouse metapodials: Evolutionary and functional implications

Creator

Reno P L; Horton W E; Elsey R M; Lovejoy C O

Publisher

Journal of Experimental Zoology Part B-Molecular and Developmental Evolution

Date

2007
2007-05

Description

Mammalian metapodials (metacarpals and metatarsals), unlike most long bones, form a single growth plate, and undergo longitudinal growth at only one end. The growth dynamics of non-mammalian tetrapod metapodials have not been systematically examined in order to determine if unidirectional growth is unique to mammals. Here we compare murine metapodial ossification in growth stages that parallel those of embryonic, juvenile and subadult American alligators (Alligator mississippiensis). Safranin O staining was used for qualitative histology, and chondrocyte differentiation and proliferation were assessed via immunohistochemistry for type X collagen and proliferative cell nuclear antigen (PCNA). We establish that growth plates form at both ends-of alligator metapodials and are maintained in the subadult. PCNA results show that alligators and mice share common patterns of chondrocyte proliferation during growth plate formation. In addition, while alligators and mice differ initially in the degree of organization and pace of chondrocyte differentiation, these parameters are largely similar in established growth plates. However, the replacement of cartilage by bone is highly irregular throughout growth in the alligator, in contrast to the more uniform process in the mouse. These results indicate that while alligators and mammals share common mechanisms of chondrocyte regulation, they differ substantially in their processes of ossification. Phylogenetic analysis indicates that the direct ossification of one epiphysis and reliance on a single growth plate is a derived character (synapomorphy) in therian mammals and likely indicates an adaptation for erect quadrupedal gait.

Subject

bone-development; bones; chondrocyte differentiation; Developmental Biology; Evolutionary Biology; indian-hedgehog; joint formation; long; morphogenesis; ossification; porpoise phocoena-phocoena; proliferation; skeleton formation; Zoology

Identifier

Format

Journal Article

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Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

283-296

Issue

3

Volume

308B

Citation

Reno P L; Horton W E; Elsey R M; Lovejoy C O, “Growth plate formation and development in alligator and mouse metapodials: Evolutionary and functional implications,” NEOMED Bibliography Database, accessed October 18, 2021, https://neomed.omeka.net/items/show/6862.

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