[Cnidaria] Answer to "Tentacle histology"

[Elsa Denker]

Hi Daniel,

We have studied the histology of Clytia hemisphaerica (hydrozoa) 
tentacle and tentacle bulb by performing Epon semi-thin sections 
followed by toluidine blue staining, so I will try answer some of your 
questions.
- First, I confirm that the dark blue structures you observe are 
nematocysts.
- Concerning the type I am not an expert but you can have a look to Gaby 
Kass-Simon's review (Can.J.Zool.80:1772–1794(2002)) and they could be 
basitrichous isorhiza or homotrichous anisorhiza (or microbasic 
mastigiphores ??). But again there is probably someone on the list that 
could give you a more accurate answer.
- I agree that your "Spir" are probably spirocytes, I also think that 
"Gland" are gland cells. For the other cell types you observe it is 
quite difficult for me to answer. I am not sure that the cell with a 
white cytoplasm is a myoepithelial cell, beacause -if it belongs to the 
same cell-, there are intriguing blue and purple apical structures that 
could be reminiscent of sensory structures (??).
- Concerning the origin of nematocytes in the anemone, I think that 
contrary to what is generally observed in hydrozoans, nematocytes are 
produced directly in the tentacles in anthozoans. (I can give you one 
reference : Jane Westfall, Cell tissue research (Zeitschrift für 
Zellforschung) 75, 381--403 (1966)).

I hope these comments will be useful for you !
Best wishes,
Elsa

-- 
Elsa Denker
PhD student
"Evolution and Development" team
UMR 7138
Université Pierre et Marie Curie (Paris VI)
Bât. A, 4e étage, case 05
7, quai Saint-Bernard
75252 Paris Cedex 05 (FRANCE)
Tel.: (33) 1 44 27 35 83



> ----- Original Message -----
> *From:* Daniel Sher <mailto:dsher at MIT.EDU>
> *To:* cnidaria at uci.edu <mailto:cnidaria at uci.edu>
> *Sent:* Friday, December 14, 2007 2:48 AM
> *Subject:* [Cnidaria] Tentacle histology
>
> Hi everyone,
>
> I am trying to understand a histological section (EPON, 2 micron, 
> Methylene Blue staining) of a tentacle of the sea anemone Nematostella 
> vectensis (attached). I'd be glad for any input about this section, 
> especially regarding:
>
> a) Am I correct that the dark structures are nematocysts? Anyone know 
> what type?
>
> b) Are the lightly-stained (and not very common) large cells in the 
> ectoderm "simply" ectodermal epithelial cells?
>
> c) What are the cells marked by a question mark? They seem to have 
> basal nuclei, but the cells themselves extend towards the surface. 
> Could they be sensory neurons?
>
> d) Any other cells I should expect to see in such a sample? 
> specifically, are there any cells (apart from ganglion cells) in the 
> ectoderm which do not extend to the surface?
>
> Also - does anyone know whether, in sea anemone, Nematocysts are 
> produced from precursors within the tentacles, or do they migrate from 
> the body column like in Hydra?
>
>
> Thanks!
> Daniel Sher
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Daniel Sher
> Postdoctoral Fellow, Chisholm lab
> Department of Civil and Environmental Engineering
> MIT
>
> Room 48-106, 15 Vassar St., Cambridge, MA 02139
> Phone 617-253-1857 (office); 617-253-8686 (Lab)
>
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