how does it happen for a zygote to develop two gametes....in the case of bisexuals
gametes develop from specialized precursor cells called germ cells, via meiosis, some species e.g earthworm, have both lines of germ cells therefore they produce both sperms (male gametes) and eggs (female gametes) Zygote is the first cell that forms after fusion of one male and one female gamete in a process called fertilization. I think u have got these two concepts mixed up. :-)
oh ok thanx let me rephrase it...hoe does it come about for some children to be born with both genitals
A zygote's genetic make up influences what kinda sex it will develop into. There are genes on both X and Y chromosomes which decide whether a person will be HE or SHE. Primitive gonads have capability of developing into both ovaries(female) and testies (male). But the androgens secreted by male fetuses will enforce these gonads to develop into testis. The androgens also cause genitalia to develop into male ones. Absence of androgens (as in female foetuses will cause female genitalia to develop) Sometimes a person's genetic make up has some abnormalities (XO or XXY instead of normal XY) he will then show abnormalities of the development of genital organs and overall secondary sexual development. Sometimes this process of development does not go as planned. There are many conditions in which this occurs. In that case a person may appear female outside but will be genetically male (and will have testis inside abdomen) sometimes along with male genitalia, a person develops female like appearance (with breasts and all). There are many other conditions like this and we really cannot generalize this description. The bottom line is if above-mentioned process goes well, HE/SHE will be a normal person, and If it does not, some sort of abnormality will be present.
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