|dc.description.abstract||This thesis presents an analysis of the normal pattern
of changes which occur in Meckel's cartilage in Xenopus
laevis during metamorphosis. The investigation has
concentrated on morphological as well as microscopic and
ultrastructural changes which take place. A method for
the preparation of the very fragile premetamorphic
cartilage for electron microscopy has been developed.
Some of the changes occurring in the cartilage were
quantified using stereological techniques.
During metamorphosis Meckel's cartilage changes from a
shallowly curved bar to a deeper "U" shape. During
this alteration, the cartilage changes from a structure
with little intercellular matrix to a tissue in which
both matrix and cellular components have increased
During the early part of metamorphic climax there is a
slow increase in the number of cells. A dramatic increase
in the cell population occurs in the middle of the period,
followed by a levelling off in the rate of cell divisions
towards the end. Metamorphic climax has therefore been
described in these three phases in this study.
These changes have been quantified by carrying out counts
on the whole cartilage and methods of analysing such
counts have been discussed.
The increase in the amount of matrix present is considerable, and largely accounts for the different appearances
before and after metamorphic climax. This increase
occurs in the later phase of climax, after the phase of
maximal cell division has taken place.
This change has been quantified using a point counting
technique, and the analysis of data from such techniques
has been described.
Sites of cell division
The areas where most cell divisions are occurring during
metamorphic climax appear to be mainly in the immediate
subperichondrial zones of the tissue.
This has been investigated by examining sections for
mitotic figures and by treating tadpoles during the
period of maximal cell division with colchicine. A
suitable method of using the drug for stathmokinesis during metamorphic climax has been described.
In addition to this investigation of normal metamorphic changes, a preliminary study of the effect on Meckel's
cartilage of exposing tadpoles to thyroid hormone
at different times during metamorphic climax has also been
undertaken, indicating that the hormone appears to act
at a specific time during climax.
At attempt has been made to correlate the changes of
shape and internal architecture of the cartilage with
the changing feeding habit of the animals.||en
|dc.publisher||The University of Edinburgh||en
|dc.relation.ispartof||Annexe Thesis Digitisation Project 2016 Block 5||en
|dc.title||Meckel's cartilage in Xenopus laevis during metamorphosis : a study of the morphological and cellular changes taking place in Meckel's cartilage during metamorphosis in Xenopus laevis (Daudin)||en
|dc.type||Thesis or Dissertation||en
|dc.type.qualificationname||PhD Doctor of Philosophy||en