ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The dermal skeleton of lungfishes is primitively composed of thick cosmine-covered bones and scales. Many Devonian lungfishes exhibit cosmine, while others have denticles of dentine and enameloid that may be arranged in several superposed layers; still others show denticles early in ontogeny superseded by cosmine later. Cosmine is a set of hard and soft tissues that includes bone, dentine, and enameloid, and a vascular and sensory porecanal network. It is the latter that uniquely distinguishes cosmine from other forms of the dermal skeleton and its presence determines the arrangement of the skeletal tissues. I have proposed that the appearance of denticles or cosmine is dependent on the stage of development of the pore-canal system, which may be fully developed as a network or arrested at the free neuromast stage. Other evolutionary trends in the dipnoan dermal skeleton have resulted from repression of the tissue interactions that produce the skeletal tissues.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1051900410
