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  #1  
Old 05-16-2005, 03:04 PM
wez nilez wez nilez is offline
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is a clit really a undeveloped penis called a "interferential organ"?

is a clitorous really a undeveloped penis called a "interferential organ"?
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  #2  
Old 05-16-2005, 03:12 PM
Mangetout Mangetout is online now
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They develop in different ways from the same structures, but to call the female version 'undeveloped' sounds a bit like a perpetuation of the ancient myth than women are imperfect versions of men.
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  #3  
Old 05-16-2005, 03:18 PM
kimera kimera is offline
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I've never heard it called an 'interferential organ' and I don't think that term applies to it anyway. A better way to phrase your question would be: Is a penis an overdeveloped clitoris? And the answer would be 'yes.' In the male, the clitoris develops into a penis and the outter labia fuse to become the scrotum.
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  #4  
Old 05-16-2005, 04:34 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
A better way to phrase your question would be: Is a penis an overdeveloped clitoris? And the answer would be 'yes.' In the male, the clitoris develops into a penis and the outter labia fuse to become the scrotum.
This sounds a bit like a perpetuation of the more recent myth that men are imperfect versions of women.
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  #5  
Old 05-16-2005, 04:54 PM
silk1976 silk1976 is offline
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Quote:
Originally Posted by kimera
I've never heard it called an 'interferential organ' and I don't think that term applies to it anyway. A better way to phrase your question would be: Is a penis an overdeveloped clitoris? And the answer would be 'yes.' In the male, the clitoris develops into a penis and the outter labia fuse to become the scrotum.
And your source for this 'factual' information is... ?
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  #6  
Old 05-16-2005, 04:55 PM
monkeyfist monkeyfist is offline
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Quote:
Originally Posted by Sofis
This sounds a bit like a perpetuation of the more recent myth that men are imperfect versions of women.
On the contrary, all fetus begin essential as bisexual. That is why men have nipples. Why do men have nipples?

So to be more accurate, the clitorus and penis both begin in a form that is neither penis or clitoris. A sort of biological placeholder for sexual organ until the baby can produce his/her own sexual hormones. But to be fair, the mother is supplying a good source of estrogen to the fetus, and the sexual organs more closely resemble female parts than male.

Fetal sexual developement is some bizarre and wacky stuff. Did you know that many newborns, both male and female, can produce milk from their nipples because of the estrogen heavy blood supply from mom? Also, some female newborns have produced a "period" like blood show shortly after birth.
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  #7  
Old 05-16-2005, 05:06 PM
Sofis Sofis is offline
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Quote:
Originally Posted by monkeyfist
On the contrary, all fetus begin essential as bisexual.
Are you being contrary to me or contrary to kimera? You responding with "on the contrary" to a direct quote of my post kind of implies the contrariness is directed at me, but as far as I can tell, you don't actually disagree with me...

(Also, I don't think 'bisexual' is quite the word to use here.)
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  #8  
Old 05-16-2005, 05:18 PM
Johanna Johanna is offline
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"Intersexed."
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  #9  
Old 05-16-2005, 05:27 PM
kimera kimera is offline
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Quote:
Originally Posted by Sofis
This sounds a bit like a perpetuation of the more recent myth that men are imperfect versions of women.
Nah, it's just basic biology. We all start out as heading towards female and then a gene which is typically found on the Y chromosome either activates or doesn't. If it activitates then the fetus typically develops into a male, although if testosterone is not properly recieved by the fetus then the child will have female genitalia although she is XY.

Here are the equivalents of other parts.
Shaft of clit - shaft of penis
Hood of clit - foreskin of penis
Labia majora - sac
Labia minora - underside of penile shaft
ovaries - testes

silk1976, basic human biology. Go take a human sexuality course at your local college.
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  #10  
Old 05-16-2005, 05:44 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
Nah, it's just basic biology. We all start out as heading towards female and then a gene which is typically found on the Y chromosome either activates or doesn't.
Under normal development, a fetus with Y-chromosomes will develop into a male, while a fetus without Y-chromosomes will develop into a female. I do not see how this consitutes "starting out as heading towards female".

I am aware that female and male sex organs both develop from the same proto-organs. But it does not make sense to consider this early development to be 'female'. Precisely because the early development of male and female fetuses is identical, it does not belong to one sex more than the other.
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  #11  
Old 05-16-2005, 06:05 PM
kimera kimera is offline
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Quote:
Originally Posted by Sofis
Under normal development, a fetus with Y-chromosomes will develop into a male, while a fetus without Y-chromosomes will develop into a female. I do not see how this consitutes "starting out as heading towards female".
No, in humans, it is not just the Y-chromosome that results in the development of the male. There is a certain region on the Y-chromosome which results in the development of the testes which results in testosterone which results in the development of the male genitalia. If this specific region is not present, the fetus will continue developing into a female. So, if testosterone is not properly recieved by the fetus, female genitalia will result so you end up with a child that is chromosomally male but has female genitalia. In fruit flies, it is the presence of two X chromosomes that result in a female so that a XO fruitfly will be male and in birds, the situation is reversed with XY being female and XX being male, so it is an important distinction to make.
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  #12  
Old 05-16-2005, 06:34 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
No, in humans, it is not just the Y-chromosome that results in the development of the male.
No, what? Nothing you wrote contradicts what I wrote: under normal development, one set of circumstances leads to a male fetus, another set of circumstances leads to a female fetus.
There are indeed circumstances that will lead to an XY-fetus developing into a female. However, even in the case of Complete Androgen Insensitivity Syndrome, the result is not identical to an XX-woman - the woman in question will have no uterus, and testes rather than overies. And, going by Sampiro's post here, there are also cases of XX-fetuses developing into males (though I don't have any sources on that, so I'm assuming he knows what he's talking about).
So I still do not see how this adds up to female as default.
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  #13  
Old 05-16-2005, 08:47 PM
kimera kimera is offline
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We are just arguing semantics. I view the situation one way, you view it another.

Quote:
Originally Posted by Sofis
No, what? Nothing you wrote contradicts what I wrote: under normal development, one set of circumstances leads to a male fetus, another set of circumstances leads to a female fetus.
See, this is where I see it differently. The way I see it as the fetus is evolving to a female and then a mutation occurs which makes it male. I started seeing it this way after learning in my bio of sex class that males are mutated females who exist so females could have sex with each other. It's just a different way of looking at the situation. I don't know how to explain it other than drawing a chart.

Quote:
There are indeed circumstances that will lead to an XY-fetus developing into a female. However, even in the case of Complete Androgen Insensitivity Syndrome, the result is not identical to an XX-woman - the woman in question will have no uterus, and testes rather than overies.
I never said that she would be identical to an XX female. (xx-female is the correct term, not xx-woman) I was trying to show how the development is toward the female UNLESS certain conditions happen. Some people call women with AIS female, others consider them male, it depends on what you look at.

Quote:
And, going by Sampiro's post here, there are also cases of XX-fetuses developing into males (though I don't have any sources on that, so I'm assuming he knows what he's talking about).
So I still do not see how this adds up to female as default.
Yes, he does know what he is talking about. It is because there is a certain region on the Y chromosome that is responsible and if that region gets switched over you can have an XX male and an XY female.
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  #14  
Old 05-16-2005, 08:55 PM
rwjefferson rwjefferson is offline
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Quote:
Originally Posted by kimera
silk1976, basic human biology. Go take a human sexuality course at your local college.
Or surf porn sites for she-males....or so I'm told.

rwj
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  #15  
Old 05-16-2005, 10:21 PM
Darwin's Finch Darwin's Finch is offline
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Quote:
Originally Posted by kimera
See, this is where I see it differently. The way I see it as the fetus is evolving to a female and then a mutation occurs which makes it male. I started seeing it this way after learning in my bio of sex class that males are mutated females who exist so females could have sex with each other. It's just a different way of looking at the situation.
It's not a very productive way of looking at it, though. For one thing, fetuses do not "evolve", except in the literal, archaic sense of the word. In common parlance, individuals do not evolve - they develop.

Further, males are not "mutated females". One of the side effects of sexual reproduction (which is characterized by meiosis and "syngamy" [the recombination of haploid gametes]) is anisogamy - the presence of two types of sex cells. In other words, eggs and sperm evolved together. The separate sexes themselves would necessarily have to have evolved simultaneously (with one another, not necessarily with the evolution of separate sex cells themselves), as well.

As for the sex organs themselves, they begin undifferentiated. Gonadal development is regulated by genes (meaning whether you get testes or ovaries is genetic, not hormonal). The appearance of the external anatomy depends on subsequent hormonal control: if testosterone and Mullerian inhibiting substance (MIS) are not present, then external anatomy develops along female lines. If both are present, then development proceeds among male lines. But, just because subsequent development may proceed along female lines in the absence of certain hormones does not mean the embryo "begins" as female.

Or, to put it another way, it is simply not true that "the clitoris develops into a penis and the outter labia fuse to become the scrotum." Both are derived from the same progenitors, but one does not develop from the other.
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  #16  
Old 05-17-2005, 02:20 AM
Mangetout Mangetout is online now
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Quote:
Originally Posted by monkeyfist
On the contrary, all fetus begin essential as bisexual.
On the contrary? How is what you said contrary to my post (the bit you didn't quote)?
Quote:
Originally Posted by Mangetout
They develop in different ways from the same structures
Yes, they start out the same; my point is that it used to be believed (by the Greeks, IIRC) that the male form was the perfect one and the female was a corrupted copy and that this sounded similar to the theme of the OP.
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  #17  
Old 05-17-2005, 03:55 AM
irishgirl irishgirl is offline
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We're muddying the waters by talking about intersex and similar conditions, but I'll try and expand a little.

Congenital Adrenal Hyperplasia (CAH), is the most common cause of intersex, resulting in a virilised female due to overproduction of androgens by the foetal adrenal glands. It is commonly caused by a deficiency in 21-hydroxylase, one of the enzymes needed to create the steroid hormones aldosterone and cortisol. When the body cannot make aldosterone and cortisol, the excess precursors are channelled into making testosterone.

Turner's Syndrome (XO women) results in women without normal ovaries and who need exogenous progesterone and oestrogen to develop normal secondary sexual characteristics. Although they cannot conceive a genetic child of their own, they may be able to carry a pregnancy (created with a donor ovum) to term.

5-alpha reductase deficiency is an enzyme deficiency which means that testosterone isn't properly converted to dihydrotestosterone, a more available form of the hormone. Because of this male babies are born with feminised external genitalia, but male internal genitalia. If the condition is not recognised, or left uncorrected (as often happens in the developing world) during puberty the amount of testosterone producd by the testes is so great that some of it is able to overcome the block, and considerable virilisation occurs. In this case the male habitus at puberty is associated with gender conversion, so the formerly female child will often self-identify as male. HOWEVER, in the west, if this disorder is recognised early, the testes will be removed prior to puberty (because of the risk of cancer if they are left abdominally) and the child will continue to be raised, and usually identify, as female.

Androgen Insensitivity (formerly known as Testicular Feminisation Syndrome) is the condition normally associated with XY women. In this case the male foetus produces lots of androgens, but the cells do not have the correct receptors, and so the androgen has not effect. These individuals are born with externally feminised genitalia, and unlike with 5 alpha reductase deficiency, this will never spontaneously correct. If testes are present in the abdomen, they are removed, and the child is given female hormones at puberty. These individuals will almost always have a female habitus and gender identity.

True hermaphroditism (possesing both ovaries and testes) is incredibly rare.
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  #18  
Old 05-17-2005, 05:03 AM
Sarah Woodruff Sarah Woodruff is offline
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To hijack somewhat:
Wasn't Wallis Simpson supposed to have had Androgen Insensitivity? I.e., genetically XY but insensitive to the male hormones, so she externally and psychologically was a woman? Many people in this situation are apparently taller than the average XX woman, slender with slim hips and small breasts, and also quite attractive.
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  #19  
Old 05-17-2005, 05:12 AM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
We are just arguing semantics. I view the situation one way, you view it another.
In that case, we might as well answer the OP with a yes. Sure the clitoris is an underdeveloped penis. Why not? It's just a different way of looking at things...

Quote:
Originally Posted by kimera
See, this is where I see it differently. The way I see it as the fetus is evolving to a female and then a mutation occurs which makes it male. I started seeing it this way after learning in my bio of sex class that males are mutated females who exist so females could have sex with each other. It's just a different way of looking at the situation. I don't know how to explain it other than drawing a chart.
Quote:
Originally Posted by kimera
(xx-female is the correct term, not xx-woman)
Thank you for the correction. I am somewhat hesitant, however, of taking terminology advice from someone who refers to an ordinary stage in fetal development as a "mutation".
I don't know whether your teacher in that course was afflicted with incompetence or politics or something else, but whatever it was, they didn't do a very good job teaching you.

Quote:
Originally Posted by kimera
I was trying to show how the development is toward the female UNLESS certain conditions happen.
And the development is toward the male UNLESS certain other conditions happen. And sometimes NEITHER set of circumstances occur, and you get an intersexed individual.

Quote:
Originally Posted by kimera
Yes, he does know what he is talking about. It is because there is a certain region on the Y chromosome that is responsible and if that region gets switched over you can have an XX male and an XY female.
AIS is cause by a mutated gene on the X-chromosome. XX carriers of the gene show some of the symptoms of AIS, such as decreased pubic hair. I would like a cite that the Y-chromosome is involved.
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  #20  
Old 05-17-2005, 06:50 AM
lee lee is offline
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Quote:
Originally Posted by monkeyfist
On the contrary, all fetus begin essential as bisexual. That is why men have nipples. Why do men have nipples?
Fetal sexual developement is some bizarre and wacky stuff. Did you know that many newborns, both male and female, can produce milk from their nipples because of the estrogen heavy blood supply from mom? Also, some female newborns have produced a "period" like blood show shortly after birth.
Adult men can spontaneously produce milk in the right circumstances and can be induced to produce milk with hormones.

TMI alert
SPOILER:
Loren's was more like a full blown nearly week long period passing clots and all just like mommy; seemingly with cramps and all poor thing. The doctor checked her with those little lighted things they look into your ears with to make sure that the blood and clots were coming fromher cervix, which they were. He also did blood cellcounts to make sure she was not becoming anemic from the blood loss. She did not, but there was a lot of blood for such a little person to lose.
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  #21  
Old 05-17-2005, 11:31 AM
kimera kimera is offline
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Quote:
Originally Posted by Darwin's Finch
If both are present, then development proceeds among male lines. But, just because subsequent development may proceed along female lines in the absence of certain hormones does not mean the embryo "begins" as female.
Oh, I don't think it begins as female, just heading towards female. That's what I was taught in my most recent course and I didn't think much of the teacher, so I won't be surprised if it is wrong.

To help fight my own ignorance, here is what I was taught, please tell me what part of this is wrong and what is correct:

Since there are some species which exist composed of only females, it brings up the problem of why males exist at all if a species of females can survive on its own. Well, as it turns out, sexual reproduction is more benefitial to the species than asexual reproduction because of the variety of genotypes. The species starts out as all female and then one female produces a modified female, who produce, instead of eggs, mobile offspring (sperm) so that they can mate with other females and produce hybrid offspring. This is why the Y chromosome is less genetically healthy than the X chromosome.

Thanks.

Quote:
Originally Posted by Sofis
AIS is cause by a mutated gene onn. the X-chromosome. XX carriers of the gene show some of the symptoms of AIS, such as decreased pubic hair. I would like a cite that the Y-chromosome is involved.
Sampiro wasn't talking about AIS, as far as I can tell, so I wasn't talking about AIS when I responded. AFAIK, AIS-XX women are normal women.
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  #22  
Old 05-17-2005, 11:55 AM
Excalibre Excalibre is offline
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Quote:
Originally Posted by kimera
Since there are some species which exist composed of only females, it brings up the problem of why males exist at all if a species of females can survive on its own. Well, as it turns out, sexual reproduction is more benefitial to the species than asexual reproduction because of the variety of genotypes. The species starts out as all female and then one female produces a modified female, who produce, instead of eggs, mobile offspring (sperm) so that they can mate with other females and produce hybrid offspring. This is why the Y chromosome is less genetically healthy than the X chromosome.
The idea that there are species that are all female seems bizarre to me. I don't even understand what that could mean - there are species without sexual differentiation, sure. But that means they're not female, I'd say. Again, it's semantics, but I don't see how you can characterize a species without sex as belonging to a sex.
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  #23  
Old 05-17-2005, 01:39 PM
Darwin's Finch Darwin's Finch is offline
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Quote:
Originally Posted by kimera
Oh, I don't think it begins as female, just heading towards female. That's what I was taught in my most recent course and I didn't think much of the teacher, so I won't be surprised if it is wrong.
It's not really the case that it's "heading towards female", either. The hormones produced are largely the result of which gonads are present (or absent, as the case may be). Since gonadal development is under genetic control, then subsequent genetic development is, ultimately, under genetic control, as well. In some cases, development does proceed diffrently, of course, and we get into cases of individuals who are genetically one sex, but who develop sexual characteristics of the opposite sex. But, if things proceed "as planned", for lack of a better term, then the goands are produced based on genetics, and those gonads begin producing hormones which regulate further development (at least in the case of males; MIS and testosterone are both produced by the testes, so once those form, the rest will theoretically fall into place).

Again, the simplest description is that a fetus is initially sexually undifferentiated, then develops into one sex or the other based on certain genetic / hormonal parameters.

Quote:
Since there are some species which exist composed of only females, it brings up the problem of why males exist at all if a species of females can survive on its own. Well, as it turns out, sexual reproduction is more benefitial to the species than asexual reproduction because of the variety of genotypes. The species starts out as all female and then one female produces a modified female, who produce, instead of eggs, mobile offspring (sperm) so that they can mate with other females and produce hybrid offspring. This is why the Y chromosome is less genetically healthy than the X chromosome.
I don't know of any species which are composed solely of females. There are species in which development does default along female lines, unless there is a good reason to create males (e.g., aphids; such species generally also have the means to reproduce via parthenogenesis, and many such species typically do not possess sex chromosomes at all - rendering the entire concept of "what sex is it?" somewhat irrelevant), and there are species in which various environmental parameters can control the resulting sex (e.g., some amphibians and reptiles, wherein the resulting sex can be controlled by the ambient temperature).
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  #24  
Old 05-17-2005, 02:35 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
Sampiro wasn't talking about AIS, as far as I can tell, so I wasn't talking about AIS when I responded. AFAIK, AIS-XX women are normal women.
Then what are you talking about? Do you have a name for this condition, with the region on the Y-chromosome getting switched over (to what? The X-chromosome?)?
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  #25  
Old 05-17-2005, 04:35 PM
kimera kimera is offline
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Quote:
Originally Posted by Darwin's Finch
I don't know of any species which are composed solely of females.
There is a species of lizards in the America Southwest which is entirely composed of females. My teacher apparently studied them for his dissertation so I assumed that he knew what he was talking about when he said that the default is female and male is a mutation that occured in the course of evolution. His definition of female was screwy too, I now see. He said that females were creatures that could reproduce and males do not have the ability to reproduce but just aid females in reproduction. That's wrong too, I bet.

Sofis, I do not think the condition has a name, it is normally the result of mocaism. For example, there were a male and female twin who were mosaic and the male twin had 30% XY and 70% XX. The female twin had 22% XY and 78% XX. The region of the Y chromosome, which is known as (sex-determining region Y) was present in the male but not the female.

Here is a page which talks about these cases.

Quote:
SRY (for sex-determining region Y) is a gene located on the short (p) arm just outside the pseudoautosomal region. It is the master switch that triggers the events that converts the embryo into a male. Without this gene, you get a female instead. It appears, then, the femaleness is the "default" program.
Since they say that female is the 'default' program, I assumed that the fetus were heading towards female development and it was the interaction of the SRY which made the fetus become male instead.
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  #26  
Old 05-17-2005, 05:03 PM
Darwin's Finch Darwin's Finch is offline
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Quote:
Originally Posted by kimera
There is a species of lizards in the America Southwest which is entirely composed of females. My teacher apparently studied them for his dissertation so I assumed that he knew what he was talking about when he said that the default is female and male is a mutation that occured in the course of evolution. His definition of female was screwy too, I now see. He said that females were creatures that could reproduce and males do not have the ability to reproduce but just aid females in reproduction. That's wrong too, I bet.
So would I. According to this paper (.pdf document),
Quote:
The sex determination mechanisms in Sauria are not yet completely understood. Sex chromosome evolution in lizards is considered to be relatively recent and data from some families suggest that they have multiple origins (Beçak, 1983). There are species with chromosomal sex determination mechanisms ascribed to male heterogamety in the families Iguanidae (see Frost & Etheridge, 1989), Lacertidae, Teiidae, Scincidae, and Pygopodidae; female heterogamety is known in the families Gekkonidae, Varanidae, and Lacertidae (for a review, see Peccinini-Seale, 1981 and references therein). In the genus Cnemidophorus, Cole et al. (1969) and Bull (1978) reported a chromosomal sex determination mechanism of the type XX:XY for Cnemidophorus tigris.

[...]

Several populations of C. lemniscatus have been intensively studied so as to clarify the nature and origins of parthenogenesis within the group (Peccinini-Seale, 1989; Sites et al., 1990, and references therein). Geographic variation exists in the karyotype; while no chromosomal sex determination mechanism has been found. Within South American lizards, only two other species of Cnemidophorus, besides those of the lemniscatus group, have been karyotyped: the bisexual species C. lacertoides (Cole et al., 1979) and the unisexual species C. nativo (Rocha et al., 1997).

[...]

This study describes the karyotype and the meiosis of a population of the endemic C. littoralis from the locality type for the species (Restinga da Barra de Maricá in Rio de Janeiro State, Southeastern Brazil), which presents a chromosomal sex determination mechanism of the type XX:XY.
From the sound of things, only a few species have actually been karyotyped, and at least some of those species which are unisex have no sex chromosomes. Thus, the "female" label seems to be pretty arbitrary. Plus, the fact that there are apparently species with "male heterogamety" kind of throws a wrench in the supposition that males are unable to reproduce.
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  #27  
Old 05-17-2005, 06:21 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
Sofis, I do not think the condition has a name, it is normally the result of mocaism.
It lacking a name seems very unlikly; scientists are a very naming-happy bunch, and if they encounter a condition even slightly out of the ordinary, they tend to name it, often in Latin. Sometimes it's named more than once.

Quote:
Originally Posted by kimera
For example, there were a male and female twin who were mosaic and the male twin had 30% XY and 70% XX. The female twin had 22% XY and 78% XX. The region of the Y chromosome, which is known as (sex-determining region Y) was present in the male but not the female.
Wait... you're talking about a pair of fertilized eggs, one XX and one XY, that merged, mixing their cells... and then split again, into two separate embryos, both being a mix of XY and XX cells... but one of them developed into a female, because the sex-determining regions on her Y-chromosomes had all been... moved elsewhere? Or are you talking about four separate fertilized eggs that paired up and merged? Or something else entirely?
I don't think I understand your example.

Quote:
Originally Posted by kimera
Here is a page which talks about these cases.


Since they say that female is the 'default' program, I assumed that the fetus were heading towards female development and it was the interaction of the SRY which made the fetus become male instead.
The thing about how you're describing it is that you make it sound as if early fetal development is a very female affair that does its female thing and is very, very female
and suddenly it grinds to a screeching halt, turns around, and heads off in the opposite direction, doing stuff that has nothing to do with the all-female things that went before.
It's a branching point. First comes stuff that is common to both sexes, then there's differentiation depending on a certain factor. Now, sure, that factor is the presence or absence of a set of genes on the Y-chromosome, but that doesn't mean it's meaningful to count the early development as being female. It lends itself as well to male development as it does to female development.
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  #28  
Old 05-17-2005, 07:07 PM
kimera kimera is offline
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Quote:
Originally Posted by Sofis
It lacking a name seems very unlikly; scientists are a very naming-happy bunch, and if they encounter a condition even slightly out of the ordinary, they tend to name it, often in Latin. Sometimes it's named more than once.
Well, if you can find a name, let me know. I find this type of stuff fascinating!

Quote:
Wait... you're talking about a pair of fertilized eggs, one XX and one XY, that merged, mixing their cells... and then split again, into two separate embryos, both being a mix of XY and XX cells... but one of them developed into a female, because the sex-determining regions on her Y-chromosomes had all been... moved elsewhere? Or are you talking about four separate fertilized eggs that paired up and merged? Or something else entirely? I don't think I understand your example.
Unfortunately, I returned the book which contained details of this particular case to the library and I can't find the case online, so I don't know exactly how that cases ended up the way it did. I do know that there were two fertilized eggs, but they never merged together, they just shared a lot of genetic material.

But I can give you information about other cases involving mosaics. This site explains how :

Quote:
This region can be transferred to the X chromosome in a rare recombination event during meiosis. The resulting sperm carry an X chromosome but direct the development of an embryo as a male, since they also contain the SRY region.
More info here, and here, and here.

Quote:
The thing about how you're describing it is that you make it sound...It's a branching point. First comes stuff that is common to both sexes, then there's differentiation depending on a certain factor. Now, sure, that factor is the presence or absence of a set of genes on the Y-chromosome, but that doesn't mean it's meaningful to count the early development as being female. It lends itself as well to male development as it does to female development.
Yeah, I didn't mean that at all, I was trying to explain the branching but not doing a very good job. I'm horrible at getting across what I am trying to say in english. That's why I said I needed to draw a diagram because then you would understand what I am trying to say. I said 'on the way to female development' instead of 'female' because I wasn't sure the correct technology to use to describe the branching off. So basically, I think we were in agreement the whole time.
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  #29  
Old 05-17-2005, 07:26 PM
Sofis Sofis is offline
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Quote:
Originally Posted by kimera
Unfortunately, I returned the book which contained details of this particular case to the library and I can't find the case online, so I don't know exactly how that cases ended up the way it did. I do know that there were two fertilized eggs, but they never merged together, they just shared a lot of genetic material.
If there was no merging, I don't see how they could have become mixes of XY and XX cells.
But I guess it's not important.

Quote:
Originally Posted by kimera
Yeah, I didn't mean that at all, I was trying to explain the branching but not doing a very good job. I'm horrible at getting across what I am trying to say in english. That's why I said I needed to draw a diagram because then you would understand what I am trying to say. I said 'on the way to female development' instead of 'female' because I wasn't sure the correct technology to use to describe the branching off. So basically, I think we were in agreement the whole time.
Well, that's good. Glad to hear it .
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  #30  
Old 05-17-2005, 08:20 PM
Tamerlane Tamerlane is offline
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Quote:
Originally Posted by Darwin's Finch

From the sound of things, only a few species have actually been karyotyped, and at least some of those species which are unisex have no sex chromosomes.
Actually if I recall correctly ( all of my Cnemidophorus/Aspidoscelis stuff is at home, so I can't immediately check it - it's also mostly at least a decade out of date ) most, or at least many of the North American Cnemidophorus have been karyotyped and they're rather more diverse than there congeners in South America. The American Southwest/Northern Mexico is ground central for the genus, as it is for a few others reptiles like Crotalus.

Quote:
Thus, the "female" label seems to be pretty arbitrary.
No it's pretty standard terminology for parthenogenetic/unisexual whiptails. They all arose instantaneously through interspecific hybridization events and in addition to being parthenogentic they appear capable of further back-crossing with bisexual species to form triploid parthenogens - hence the origin ( probably multiple and of possibly different source species ) of lineages like Asipidoscelis exsanguis or A. velox.

- Tamerlane
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  #31  
Old 05-18-2005, 12:34 AM
Darwin's Finch Darwin's Finch is offline
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I stand corrected then. Thanks for the info, Tamerlane.

I don't think that changes the overall points about a) females and males, regardless of species, differentiate from a common developmental progenitor, rather than development proceeding along one line and changing under whatever circumstances, and 2) males aren't "mutations" based on a female body plan.

I could still be wrong, of course
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  #32  
Old 05-18-2005, 01:15 AM
Tamerlane Tamerlane is offline
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Quote:
Originally Posted by Darwin's Finch
I don't think that changes the overall points about a) females and males, regardless of species, differentiate from a common developmental progenitor, rather than development proceeding along one line and changing under whatever circumstances, and 2) males aren't "mutations" based on a female body plan.

I could still be wrong, of course
If so, then so am I, as I pretty much agree .

- Tamerlane
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  #33  
Old 05-18-2005, 04:50 AM
Sarah Woodruff Sarah Woodruff is offline
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Oh my God, civilised agreement after a difference of opinion!
You're both highly evolved people.
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