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In all the examples I can think of, (mostly vertebrate), female meiosis, or oogenesis, only haploid gamete is produced while the other cell divisions result in polar bodies. While male meiosis results in 4 haploid gametes. This difference follows the fundamental definition of female and males being defined as resources committed into reproductive cells.

I want to know if this asymmetrical gamete production is truly universal across all organisms. Are all meiosis in plants or unicellular organisms unequal between male and female?

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  • $\begingroup$ almost two years later and I'm returning to this question because I found a interesting paper relevant to this question. Turns out gametogenesis is much more variable than I ever knew. "No universal differences between female and male eukaryotes: anisogamy and asymmetrical female meiosis" onlinelibrary.wiley.com/doi/10.1111/bij.12874/full $\endgroup$
    – petersoapes
    Sep 22, 2016 at 2:42

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Plant meiosis gives rise to four megaspores but usually upto three of them die by apoptosis leaving only one megaspore. But they are symmetric and three of them need not die all the time as it seems [REF].

Plasmodium being a haploid organism undergoes meiosis after fusion of gametocytes. Sexual differentiation is initiated at some point during the merozoite stage (See here and also the cross references).

Chlamydomonas is also haploid during its vegetative phase, and produces four flagellated haploid gametocytes. Sexual differentiation is apparently stochastic.

Perhaps there are more examples of organisms that do not undergo asymmetric division as seen in metazoa. There may be some stochastic asymmetry which leads to differentiation of sexes in the haploid unicellular eukaryotes and apoptosis in plant megaspores; these stochastic events may happen later as well. For plasmodium this is not really known; others I am not sure of.

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