At 8:04 AM -0500 9/5/99, walter mozgala wrote:
>Ross,
>>I think caling the polen grain wall the wall of the microspore is
>leaving out much post microspore development. The microspore wall is
>present after meiosis and cytokinesis. I would assign pollen grain wall
>development, including protein injection, etc., to nicrogametophyte
>development. So the pollen wall is new, and formed post meiosis.
>>again, my two coconuts worth
>>Walter J Mozgala
>Profesor of Botany
>>Holyoke Community College
>SEM Division
>303 Homestead Ave
>Holyoke, MA 01040
>>wmozgala at hcc.mass.edu>(413) 552-2470
Hi Walter!
My take on that though was that the wall development
was mostly pre-mitotic, making it microsporic rather than
microgametophytic. I'll bet there are probably examples
of both. In my teaching I usually stress that this
wall is the modified microspore wall because I want
students to remember the source, the natural history,
of this microgametophyte...that it is endosporic. It
is INDEED altered but it is ALSO the microspore wall.
The tube cell has no wall of its own and neither does
the generative cell of the microgametophyte. In lab
our students are usually looking at prepared slides
of lily anthers. It is obvious that the "ornamentation"
is in place when the contents of the cell consist of
just ONE cell (ie the microspore). Certainly I think
the students can see that there is additional cutinization
of this wall when there are TWO cells inside the wall.
But the point is that what they see is a wall that was
"in place" at the microspore stage...perhaps glorified
at the microgametophyte stage...but microsporic in
origin as a cell wall.
ross
________________________________________________________________
Ross Koning | koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA | fax: 860-465-4479
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