Annelida colleagues,
A correction. One of the abstracts had extraneous text from another
abstract pasted in front. In the paper by Bartolomaeus please delete all
the abstract text before "In Annelida, nearly each ..." The correct cite is
given in full below.
An explanation. Most will know what to do with 'refer format' citations. But
if you've never heard of 'refer' then it's a widely-used tagged-field
convention used for exchanging citations between bibliographic
programs. Please don't try to read the message onscreen or as a
printout. Instead save it as a file and then load it into your bibliographic
program using its import facility. Since the output came from EndNote,
users of that program will have no trouble. (In fact in Pegasus mail, as
long as the message is still in the 'new mail' folder, you don't even need to
save the file first. Simply note the name of the temporary file created for
the message ( this is given under the 'info' button) and go find it with
EndNote). A click of the mouse and it's in your database!
Finally the keyword HYDROBIOLOGIA402 is for rapidly selecting this
group of references and is not an error.
============================
%0 Journal Article
%A Bartolomaeus, Thomas
%D 1999
%T Structure, function and development of segmental organs in Annelida %J
Hydrobiologia %V 402 %P 21-37 %K ANNELIDA; REPRODUCTION; HYDROBIOLOGIA402;
EVOLUTION; ANNELIDA; NEPHRIDIA; ULTRASTRUCTURE %X In Annelida,
nearly each segment contains a pair of ducts that either are
protonephridia or metanephridia. These segmental organs function as
excretory organs and, after having been modified, they may also act as
gonoducts during maturity. In certain polychaetous annelids and especially
in clitellates this function has been adopted by additional gonoducts
which generally are formed at the begining of maturity. At the end of the
last century the gonocoel theory tried to explain the relation between
gonads, coelomic cavities and nephridia. Using the gonocoel theory
axiomatically, Goodrich (1945) assumed that in annelids a pair of
protonephridia and a pair of gonoducts represent the primary condition.
Evolution of metanephridia on the one hand and the fusion of gonoducts and
nephridia on the other hand occurred within the Annelida. Based on recent
ultrastructural investigations into the development of different segmental
organs, this paper re-evaluates Goodrich's hypothesis. According to these
data the segmental organs differentiate from a single anlage. Each
consists of three or four cells which line a small lumen filled with
microvilli. The duct becomes ciliated and the most proximal cells are
separated when the coelom extends by fluid accumulation between the lining
cells. During enlargement of the coelomic cavity the proximal part of the
anlage is passively opened, so that the cilia face the coelom, to form the
funnel. If separation of the proximal duct cells is suppressed, the anlage
differentiates into a protonephridium, which secondarily may acquire a
funnel during maturity by proliferation of proximal duct cells. Thus,
different pathways in nephridial development lead to completely different
segmental organs in the fertile adult. Additional gonoducts evolve in
different lineages within the annelids.
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