Abstract

Developmental Morphogenesis of Cement Glands and Attachment Organs in lower vertebrates

Martin MINARIK, B.Sc. Thesis
Department of Zoology, Vertebrate Zoology Research Group, Charles University
Viničná 7, 12844 Prague (Czech republic)
E-mail: minarik3@natur.cuni.cz

Supervised by Mgr. Robert Cerny, Ph.D. (homepage)

Keywords: Polypterus senegalus, adhesive organ, cement gland, larvae, vertebrates

Various types of adhesive organs are present among almost all groups of these vertebrates which have primarily aquatic larvae. Their function is usually to allow the larva to attach itself to a substrate immediately after hatching using a mucous secretion, and remain in a safe place until it is capable of feeding or active swimming. The morphology of these structures shows conspicuous differences between some taxa, but adhesive cells, the main mass of the organs, show many common features. Many authors claim that adhesive organs can be homologous among at least some groups of vertebrates. Reflections on this topic are complicated by the findings of some authors, suggesting that cement organs of the bichir (Polypterus senegalus) and the bowfin (Amia calva) arise from endodermal layer, whilst similar structures in other taxa are probably ectodermal in origin. The most examined adhesive structure is the cement gland of Xenopus laevis. Some important markers and gene interactions leading to the cement gland formation were first described on this model. Thus, in order to resolve the question of homology, it will be necessary to identify the mechanisms of the cement organ development in other taxa. Using the markers which were previously described in Xenopus or comparing expression patterns in developing cement organs will be suitable.

This bachelor thesis reviews the existing knowledge of adhesive structures in lower vertebrates. In my next study I will focus on the morphogenesis of the cement organs in the bichir Polypterus senegalus and their comparison with other taxa.

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