Aspects of tissue morphogenesis and organisation in the zebra fish, Brachydanio rerio
Abstract
This thesis is mainly concerned with the impact of cellular
mechanisms which influence a particular instance of tissue
morphogenesis, namely development of the caudal fin of the
zebra fish, Brachydanio rerio.
Ultrastructural analysis of fin fold morphogenesis in situ
reveals that specific changes in epidermal cell shaping occur
as a transient ectodermal ridge is generated. The ridge is
converted to a fin fold by further changes in cell shaping
which are spatio-temporally associated with the deposition
of extracellular matrix material.
Microsurgical excisions of small portions of early folds
support the suggestion that cell shape modulation and extracellular matrix organisation interact reciprocally during early
fold formation. Studies using cytochalisin B show that actinoid
microfilaments play an important role in generating the changes
in epidermal cell shaping associated with fin fold morphogenesis.
They also eJiminate the possibility that overlying peridermis
and e(Xiermis which flank putative fin folds exert any great
influence on the morphology of fold epidermis during apical
ectodermal ridge generation. Furthermore, experiments employing tunicamycin indicate that cell adhesion and extracellular
matrix deployment are partic.llarly important in converting
the apical ectodermal ridge into a fin fold and in subsequent
stabilisation of the early fin fold. Microtubules do not appear
to influence early fin fold morphogenesis although they are
important during a later phase of fin fold expansion.
The spatial relationships between extracellular matrix
orientation and cytoskeletal alignment in cell layers associated with the scales of certain teleosts have also been assessed.
These studies have involved electron and immunufluorescence
microscopy. They show that fibroblastic cells found at varying
locations on the surfaces of scales display three types of micro-
tubule arrays. Two of these arrays show intercellular alignment
of microtubules which are spatially correlated with patterns
of extracellular matrix deposition.
Type
Thesis, PhD Doctor of Philosophy
Rights
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http://creativecommons.org/licenses/by-nc-nd/4.0/
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