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Oedogonium (Chlorophyceae)

 

Oedogonium sp. showing multiple chloroplasts, starch-forming bodies (pyrenoids), and cell division rings. Modified from an image at nifty.com

 

 

Oedogonium sp. trichome with multiple cell division rings. Modified from an image at nifty.com

 

 

Oedogoniuim sp. with cell division rings. Modified from an image at the University of Wisconsin.

 

 

Oedogonium sp. oogonium. Modified from an image at the University of Wisconsin.

 

 

Oedogonium sp. germling.

 

 

Oedogonium filament with visible sheath, punctuated at cell cross walls. Modified image

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Oedogonium sp. zygote. Modified from an image at the University of Wisconsin.

 

 

Oedogonium sp. antheridium and division rings. Modified from an image at the University of Wisconsin.

 

 

Oedogonium sp. trichomes heavily encrusted by periodic attachment of Gomphonema (stalked diatoms) as epiphytes on Oedogonium trichomes.

 

 

Gomphonema (stalked diatoms) as epiphytes on Oedogonium trichome.

 

 

A mass of Oedogonium non-branching trichomes.

 

 

Gomphonema (stalked diatoms) as epiphytes on Oedogonium trichomes.

 

 

Gomphonema (stalked diatoms) as epiphytes on Oedogonium trichomes.

 

 

Oedogonium 'dwarf male' development from attachment (Fig. 1) through production of two male gametes per nanandrium (Figs. 8-13) and release of gametes (Fig. 14).
From D’Amico, Leonardi and Cáceres 2013.

 

D’Amico, S.L., P.I. Leonardi and E.J. Cáceres  2013.  Ultrastructure of multicellular dwarf males with external gametangium in Oedogonium macrandrium (Oedogoniales, Chlorophyta).  Biocell 37(3):85-91.

 

 

Oedogonium sp. dwarf male attached to female filament near oogonium (inflated cell)

Zoospore released from sporangium of the same or a different macrofilament is chemically attracted to the oogonium and attaches to it or an adjacent somatic cell.  It produces a dwarf filament by repeated mitotic divisions, then undergoes meiosis producing two flagellated microgametes (‘spermatozoids’) that are released and swim to the surface of the oogonium where normally one of the gametes fertilizes the egg, if it is successful.  Polyspermy, presumably because of plasmogamy (fusion of cell contents without fusion of nuclei, common in fungi), has been observed in Oedogonium (Hoffman 1973).

Modified from photograph at 'Soft-bodied stream algae of California' by Rosalina Stancheva, Robert Sheath and Lilian Busse, University of Colorado at Boulder, posted online.

Hoffman, L.  1973.  Fertilization in Oedogonium.  II.   Polyspermy.  Journal of Phycology 9:296-301.  online

 

Oedogonium sp. with apical rings following at least four cell divisons
Photograph by Emily Wright, Susquehanna University, posted
online

 

Oedogonium sp. with ~15 apical rings, from Lake Cochichewick, North Andover MA, USA
18 Oct. 2016

 

 

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