{{Distinguish|Oogamy}} {{more citations needed|date=October 2015}}
[[Image:Hyaloperonospora-parasitica-hyphae-oospore-2.jpg|thumb|right|300px|Oospores of ''Hyaloperonospora parasitica'', agent of the downy mildew (in the middle)]] An '''oospore''' is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, certain fungi, and oomycetes, which are fungus-like stramenopiles rather than true fungi.<ref>{{Cite book|last=Tronsmo|first=Anne, M.|title=Plant Pathology and Plant Disease|publisher=CABI|year=2020|isbn=978-1789243178}}</ref> They are believed to have evolved either through the fusion of two species or the chemically induced stimulation of mycelia, leading to oospore formation.<ref>{{cite journal|title=Chemical Stimulation of Oospore Formation in Phytophthora capsici|first1=J. Y. |last1=Uchida |first2=M. |last2=Aragaki|journal=Mycologia|volume=72|issue=6|pages=1103 |doi=10.2307/3759563|jstor=3759563 |year=1980 }}</ref>
In Oomycetes, oospores can also result from asexual reproduction, by apomixis. These haploid, non-motile spores are the site of meiosis and karyogamy in oomycetes.<ref>{{cite web |last1=Fry |first1=William, E. |title=Introduction to Oomycetes |url=https://www.apsnet.org/edcenter/disandpath/oomycete/introduction/Pages/IntroOomycetes.aspx |website=American Phytopathological Society |access-date=29 March 2021}}</ref>
A dormant oospore, when observed under an electron microscope, has led researchers to draw conclusion that there is only a single central globule with other storage bodies surrounding it.<ref>{{Cite journal|last=Ruben|first=D.M|date=May 1978|title=Ultrastructure of Oospore Germination in Pythiumaphanidermatum|url=https://www.jstor.org/stable/244258|access-date=2021-04-04|journal=American Journal of Botany|volume=65 |issue=5 |pages=491–501 |doi=10.2307/2442581|jstor=2442581 |url-access=subscription}}</ref>
==References== {{reflist}}
Category:Reproduction