Deck 7: Development and Sex Determination

Question 1

As outlined in this chapter, sex can be defined at several levels: chromosomal, gonadal, and phenotypic. To this we can add psychological sex, the sex one believes themselves to be. Determining someone's sex is a complex issue that is often difficult to resolve, as the case of Bruce Reimer (see Section 7.1) illustrates. In spite of the complexity surrounding this issue, the International Olympic Committee (IOC) and the International Association of Athletics Federations (IAFF) still use sex testing on female athletes to determine whether they can compete in athletic events as females. This has led to serious personal, social, and legal issues, and the practice has been widely condemned and widely defended. Let's examine two such cases here.
An Indian athlete, Santhi Soundarajan, finished second in the 800-meter run at the Asian Games in Doha, Qatar, in 2006. After the race, she was asked to take a sex test. According to press reports, the tests showed that she "appeared to have abnormal chromosomes." An official stated that she had more Y chromosomes than allowed. As a result, she was stripped of her medal, banned from further competition by the Indian Olympic Association, and shunned by her local community. Before the race in Doha, Santhi had competed in 8 international competitions and won 12 medals. Sometime after this incident, she attempted suicide. She now runs a training school for athletes in Tamil Nadu, India. Although the number and types of tests done on Santhi have not been revealed, such tests usually involve examination of the external genitals, a chromosome analysis, and measurement of hormone levels.
Suppose you were on the committee deciding whether Santhi could compete as a female. Consider each of the following hypothetical tests one at a time and base your conclusions only on the results of that test. The results of a physical examination show she has female genitals. On this basis, would you allow her to keep her medal and compete as a female in future races Suppose the results of a chromosomal analysis shows that she has an XY chromosome set and is chromosomally male. Would you allow her to keep her medal and compete as a female Lastly, suppose a test for hormone levels shows that she has levels of the male sex hormone testosterone that are higher than average for females but at least 10 times lower than the average for males. Would you allow her to keep her medal and compete in future races as a female Now, put the results of all three tests together, and consider them as a whole. What are your conclusions
Now, let's consider the case of a South African runner, Caster Semenya, who won the 800-meter run at the World Championships held in Berlin, Germany, in 2009. After the race, she was asked to undergo sex testing. The IAAF stated that the tests were requested to ascertain whether she had a rare medical condition that gave her an unfair physical advantage. The nature of the tests and their results were not released, but press reports indicate that she did not have ovaries or a uterus, and had testosterone levels intermediate between the averages for males and females. In the end, the IAAF agreed to keep the results of her tests confidential, and Caster was allowed to keep her medal and return to international competition in 2010. In both cases, what the IAAF considers the threshold for determining who can compete as a female has not been stated.
Based on what is known about the test results in this case and the hypothetical tests in the first case, do you think the outcome in each case was fair

Answer 1

The gender tests for the female athletes were done in the two cases. The first subject-athlete contained external genitals, but had an excess of Y chromosomes, which is considered abnormality. The female hormone levels are far in less as compared to male sex hormones (testosterone). As a result, she was expelled from the sports and her medals were ceased.
Neglecting the social and legal considerations, let us analyse the case in terms of ethics. The subject possessed genitals, which depicts that she is a female, but the hormone levels and chromosome analysis conclude that she is an abnormal female. Changes in hormones are a very common issue, so the decision taken is not completely acceptable. She should have treated as per her health condition.
• Gender also depends for some extent on psychology and physical activities. A gymnast or a skinny girl complete the anaphase of meiosis in ovaries, late at the age of 16, but a healthy normal can finish the cycle at an early age; sometimes may be at the age of 11. Thus, gender determination also depends on external activities.
• For these reasons, she could have given a chance after finishing the treatment. In the second case, the athlete was thwarted from undergoing the woe, though she did not possess genitals. The sex testing rules have to be modified. If the candidates do not respond to treatment, they should be allowed to play along with the athletes of their kind. Threshold levels of all the tests should be meticulously determined.
In the second case, the athlete had hormone levels somewhere between the male and female hormones, and did not have external genitals. However, the reports were kept confidential and she was allowed to play.
The transgender subjects possess higher energy levels than normal females. So, she should be treated to reduce the male hormone levels. If she responds to that, she should be allowed to play further.

Question 2

How many chromosomes are present in a human secondary oocyte as it leaves the ovary during ovulation

Answer 2

Secondary Oocytes are oocyte formed after meiosis I.
• Meiosis I divides the number of chromosome from the parent cell in half.
• The parent cell (a primary oocyte) has 46 chromosomes.
• Thus, the secondary oocytes have half of 46, or 23 chromosomes.

Question 3

As outlined in this chapter, sex can be defined at several levels: chromosomal, gonadal, and phenotypic. To this we can add psychological sex, the sex one believes themselves to be. Determining someone's sex is a complex issue that is often difficult to resolve, as the case of Bruce Reimer (see Section 7.1) illustrates. In spite of the complexity surrounding this issue, the International Olympic Committee (IOC) and the International Association of Athletics Federations (IAFF) still use sex testing on female athletes to determine whether they can compete in athletic events as females. This has led to serious personal, social, and legal issues, and the practice has been widely condemned and widely defended. Let's examine two such cases here.
An Indian athlete, Santhi Soundarajan, finished second in the 800-meter run at the Asian Games in Doha, Qatar, in 2006. After the race, she was asked to take a sex test. According to press reports, the tests showed that she "appeared to have abnormal chromosomes." An official stated that she had more Y chromosomes than allowed. As a result, she was stripped of her medal, banned from further competition by the Indian Olympic Association, and shunned by her local community. Before the race in Doha, Santhi had competed in 8 international competitions and won 12 medals. Sometime after this incident, she attempted suicide. She now runs a training school for athletes in Tamil Nadu, India. Although the number and types of tests done on Santhi have not been revealed, such tests usually involve examination of the external genitals, a chromosome analysis, and measurement of hormone levels.
Suppose you were on the committee deciding whether Santhi could compete as a female. Consider each of the following hypothetical tests one at a time and base your conclusions only on the results of that test. The results of a physical examination show she has female genitals. On this basis, would you allow her to keep her medal and compete as a female in future races Suppose the results of a chromosomal analysis shows that she has an XY chromosome set and is chromosomally male. Would you allow her to keep her medal and compete as a female Lastly, suppose a test for hormone levels shows that she has levels of the male sex hormone testosterone that are higher than average for females but at least 10 times lower than the average for males. Would you allow her to keep her medal and compete in future races as a female Now, put the results of all three tests together, and consider them as a whole. What are your conclusions
Now, let's consider the case of a South African runner, Caster Semenya, who won the 800-meter run at the World Championships held in Berlin, Germany, in 2009. After the race, she was asked to undergo sex testing. The IAAF stated that the tests were requested to ascertain whether she had a rare medical condition that gave her an unfair physical advantage. The nature of the tests and their results were not released, but press reports indicate that she did not have ovaries or a uterus, and had testosterone levels intermediate between the averages for males and females. In the end, the IAAF agreed to keep the results of her tests confidential, and Caster was allowed to keep her medal and return to international competition in 2010. In both cases, what the IAAF considers the threshold for determining who can compete as a female has not been stated.
Would you recommend that testing of female athletes be continued to ensure that males do not compete as females Or should all such testing be banned

Answer 3

Sex testing involves social, personal, and legal issues. It is so pitiable and annoying to get a disqualifying intimation after playing sports for such a long time, and achieving a lot. The athletes may be prone to severe depression and turn suicidal in nature. However, it is an intriguing situation.
Transgender individuals perform better as compared to females. So, it is not easy to take a stance. On the other hand, it should be always ensured that males do not participate in par with females in sports. Proper steps have to be taken, and any abnormal female athlete should be treated to downregulate male hormones. Sex testing can neither be denied nor be appreciated.
I would recommend examining the athlete beforehand and launching sports for such individuals too. This is not to degrade the enthusiasm of a potential player. Anyhow, the decision should be as per the prevailing situation.

Question 4

Discuss and compare the products of meiosis in human females and males. How many functional gametes are produced from the daughter cells in each sex

Question 5

A human female is conceived on April 1, 1979, and is born on January 1, 1980. Onset of puberty occurs on January 1, 1992. She conceives a child on July 1, 2004. How long did it take for the ovum that was fertilized on July 1, 2004, to complete meiosis

Question 6

The gestation of a fetus occurs over 9 months and is divided into three trimesters. Describe the major events that occur in each trimester. Is there a point at which the fetus becomes more "human"

Question 7

FAS is caused by alcohol consumption during pregnancy. It can result in miscarriage, growth retardation, facial abnormalities, and intellectual disability. How does FAS affect all of us-not just the unlucky children born with this syndrome What steps need to be taken to prevent this syndrome

Question 8

Describe, from fertilization, the major pathways of normal male sexual development; include the stages in which genetic sex, gonadal sex, and phenotypic sex are determined.

Question 9

Which pathway of sexual differentiation (male or female) is regarded as the default pathway Why

Question 10

The absence of a Y chromosome in an early embryo causes the:

A) embryonic testis to become an ovary
B) Wolffian duct system to develop
C) Müllerian duct system to degenerate
D) indifferent gonad to become an ovary
E) indifferent gonad to become a testis

Question 11

Assume that humanlike creatures exist on Mars. As in the human population on Earth, there are two sexes and even sex-linked genes. The gene for eye color is an example of one such gene. It has two alleles. The purple allele is dominant to the yellow allele. A purple-eyed female alien mates with a purple-eyed male. All the male offspring are purple-eyed, whereas half the female offspring are purple-eyed and half are yellow-eyed. Which is the heterogametic sex Why

Question 12

Give an example of a situation in which genetic sex, gonadal sex, and phenotypic sex do not coincide. Explain why they do not coincide.

Question 13

How can an individual who is XY be phenotypically female

Question 14

Discuss whether the following individuals (1) have male or female gonads, (2) are phenotypically male or female (discuss Wolffian/Müllerian ducts and external genitalia), and (3) are sterile or fertile.
a. XY, homozygous for a recessive mutation in the testosterone biosynthetic pathway, producing no testosterone
b. XX, heterozygous for a dominant mutation in the testosterone biosynthetic pathway, which causes continuous production of testosterone
c. XY, heterozygous for a recessive mutation in the MIH gene
d. XY, homozygous for a recessive mutation in the SRY gene that abolishes function

Question 15

It has been shown that hormones interact with DNA to turn certain genes on and off. Use this fact to explain sex-limited and sex-influenced traits.

Question 16

What method of sex testing did the International Olympic Committee previously use What method did it use subsequently Does either of these methods conclusively test for "femaleness " Explain.

Question 17

Explain why pattern baldness is more common in males than in females even though the gene resides on an autosome.

Question 18

Calico cats are almost invariably female. Why (Explain the genotype and phenotype of calico females and the theory of why calicos are female.)

Question 19

How many Barr bodies would the following individuals have
a. normal male
b. normal female
c. Klinefelter male
d. Turner female

Question 20

Males have only one X chromosome and therefore only one copy of all genes on the X chromosome. Each gene is directly expressed, thus providing the basis of hemizygosity in males. Females have two X chromosomes, but one is always inactivated. Therefore, females, like males, have only one functional copy of all the genes on the X chromosome. Again, each gene must be directly expressed. Why, then, are females not considered hemizygous, and why are they not afflicted with sex-linked recessive diseases as often as males are

Question 21

Individuals with an XXY genotype are sterile males. If one X is inactivated early in embryogenesis, the genotype of the individual effectively becomes XY. Why will this individual not develop as a normal male