Bud
development of
Polyandrocarpa
misakiensis
Various modes of bud development of ascidians
have been described
(eg. Nakauchi, 1982. Am.Zool, 22, 753-763),
and will be hopefully
introduced on this page in the future.
This page summarizes bud development of Polyandrocarpa
misakiensis.
An adult animal is drawn at the bottom (see alsothe
previous page).
The growing bud is an outgrowth of the parental
body wall.
The body wall consists of the outer epidermis,
inner atrial epithelium,
and several types of mesenchyme cells (blood
cells) between the two
epithelia.
The bud separates from the parent
and starts cell differentiation
and morphogenesis (upper-left). First,
the atrial epithelium at
the proximal end dedifferentiates and enters
the cell division cycle.
The epithelium in this region invaginates into
the mesenchymal space
and redifferentiates into the stomach and intestine
(upper-middle).
The pharynx (upper-right), neural gland, and
some other tissues are also
formed from the atrial epithelium through "transdifferentiation."
Both budding and regeneration include the process
to reconstruct missing parts
from the remaining tissue. Although
some human tissues have a strong
regeneration potential, we
cannot proliferate by budding. Why can ascidians
reconstruct their body from
a small pieces of the adult tissue, and why can't we?
We want to know the molecular basis and mechanisms
that enable ascidians
to reactivate developmental programs that are
usually active only during
embryogenesis.
Interesting? Go
to the next page!
Embryonic development is another fascinating subject. We are also
studying on
molecular biological aspects of the embryonic development of the ascidian
Ciona intestinalis. Visit THIS
PAGE.