The Effects of
NiCl2on
Spicule Formation
Jessica
Ann Billet, Franklin and Marshall, Class of 2000
Background
and Objective
Sea
urchins exhibit radial holoblastic cleavage, eventually
forming a blastula. Shortly after the blastula hatches from
the fertilization membrance, the embryo begins gastrulation.
Gastrulation begins when the vegetal side of the blastula
begins to thicken and flatten. This flat sheet of cells is
called the vegetal plate. In the center of the
vegetal plate a small group of cells begins to change. These
cells extend and contract long, thin filopodia. These
cells then break off from the epithelium and migrate into
the blastocoel. These migrating cells are known as the
primary mesenchyme cells (PMCS). Eventually
the migrating cells localize within the ventrolateral region
of the blastocoel. It is in this area that the PMCs fuse
together to form syncytial cables. Syncytial cables
will eventually form the axis of the calcium carbonate
spiculesof the larval
skeleton.
The
purpose of this lab is to explore the development of
spicules in a sea urchin's larval skeleton.
NiCl2interferes
with spicule and skeletal formation, by introducing half of
the embryos into a solution of
NiCl2,
we hope to observe the effects of blocking skeleton
formation. We will stain all of the embryos with an Ig8
immunoflourescent antibody. Ig8 will stain or 'tag' the
primary mesenchyme cells of the developing embryo.
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