Are all embryos originally females?

Question

In the movie "Jurassic Park," they say that all (dinosaur) embryos are female unless a certain chemical is released, which makes it a boy. I was just wondering if this was true for humans. Thanks!

Answer 1

all eggs release from a womans ovaries are female. what determines sex in humans is which sperm fertilizes the egg. one with an x chromosome bears a female, one with a y chromosome bears a male.

Answer 2

Tricky question.

The human female eggs are homogametic, which means they contain only 1 sex chromosome, the X chromosome. At this stage, the eggs are genderless. Human male sperm contains either another X chromosome or Y chromosome. Depending on which chromosome is contained in the sperm that fertilizes an egg will determine the sex of the zygote (it becomes an embryo later). If the fertilizing sperm contains an X chromosome, the zygote will be an XX (female), if it contains a Y chromosome it becomes an XY (male). The presence of the Y chromosome will eventually trigger male hormones to be released that will cause the eventual embyro to take on male characterisitics.

So the sperm determines the gender, but then hormones are released if the Y chromosome is present , which tell the zygote to start developing characterisitics of a boy.

Good luck.

Answer 3

For the 1st few weeks, an embryo is genderless (not M or F). Seven weeks after fertilization, for those embryos bearing a Y chromosome, this chromosome triggers the release of testosterone and mullerian inhibiting substance (MIS). Testosterone spurs development of testes. MIS prevents development of female structures. If the embryo did NOT bear a Y chromosome, it would have by default developed into a female.

So in simple terms, until 7 weeks, human embryos are genderless. At 7 weeks, they would default to female without the release of the hormones triggered by the presence of the Y chromosome. This leads to the common misconception that all human embryos start out female.

Answer 4

Well the egg sex cells that females have are by themselves all females because all the chromosomes are xx. But sex is determined by the male becaue the male chromosomes are xy. It the sperm gives the egg an additional x chromosome then then the fetus will be female, but if the egg recieves a y chromosome then it will be a male. And I remeber watching a show on discovery that at about 7 weeks when the fetus is developing thier sex parts if the y chromosome is present then they develop a penis if not they stay a girl....so yeah...sort of!!

Answer 5

Ehhnnnn, not exactly. Sort of.

If you define 'female' as having no Y chromosomes, and 'male' as having Y chromosomes, then no. An embryo is the gender it will be from the moment of conception.

Physiologically speaking, though, the developing embryo I believe is female until it begins producing its own hormones.

(and ya might want to consider getting scientific info from other sources than movies... ;-) )
To add to Doodlestuff's interesting gender facts, some fish change genders as they grow - starting off male when they are small, becoming female.

Answer 6

It is true for reptiles and fish (which lay eggs). I have never heard this to be true for a mammal though. Just adding hormones does not change the gender of a human. The sperm pre-determines the gender.

Example: sea turtles can determine which sex is born by how deeply they bury their eggs (apparently heat affects what develops). Fish normally would have a 50/50 ratio, but in the complete absence of one gender, some will spontaneously change to male. Amphibians do so as well, although realize that not all species within the genre can do this.

Answer 7

i think that embryos start out as no sex & then develop into either male or female. just remember that jurassic park is a movie

Answer 8

All embryos start out with girl-looking parts. If they are male embryos, the male hormones make the genitals grow to look like male parts.

Answer 9

No, gender is already determine by the father's sperm- when it's a cell. XX and XY sperm actually looked different under a microscope. XX is round swims slower, XY is sharpe and faster. So don't blame moms if you want either gender and you can't get it

Answer 10

hello,
yes its true for humans too.
Originally when the embryo is created, it starts out as a girl unless theres a hormone that changes it into a male.
you can look some more of it up online or answers.com