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Chapter 5

FRHD 2100 Chapter Notes - Chapter 5: X Chromosome, Paramesonephric Duct, Sex Steroid

Family Relations and Human Development
Course Code
FRHD 2100
Cindy Clarke

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Chapter 5 Gender Identity and Gender Roles
Gender: the psychological state of being female or male, as influenced by cultural
concepts of gender-appropriate behaviour; compare and contrast the concept f
gender with anatomic sex, which is based on the physical differences between
females and males
Gender roles the clusters of behaviour that are deemed “masculine” or
“feminine” in a particular culture
Gender Typing: the process by which children acquire behaviour that is deemed
appropriate to their sex
Prenatal Sex Differentiation
Gender Differentiation: the process by which males and females develop distinct
reproductive anatomy
Chromosomes: one of the rodlike structures found in the nucleus of every living
cell that carries the genetic code in the form of genes
When a sperm fertilizes an ovum, 23 chromosomes from the male parent
normally combine with 23 chromosomes from the female parent
Zygote: a fertilized ovum (egg cell)
23rd pair is the sex chromosome
An ovum carries an X sex chromosome, but a sperm carries either an X or a Y
Female XX
Male XY
After fertilization:
3 weeks heart begins to drive blood through the embryonic bloodstream
5 to 6 weeks the embryo is 0.5 to 1 cm lone, primitive gonads, ducts, and
external genitals whose gender cannot be distinguished visually has formed
2 sets of primitive duct strutures, the Mullerian (female) ducts and the
Wolffian (male) ducts
first six weeks or so of prental development, embryonic structures of both
genders develop along similar lines and resemble primitive female structures
7th week after conception, the genetic code begins to assert itself
Y sex chromosome causes the testes to begin to differentiate
Ovaries begin to differentiate if Y chromosome is absent
Those rare individuals who have only one X also become females, because
they lack the Y
Ovaries begin to form 11 to 12 weeks

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Embryo: the stage of prenatal development that begins with implantation of a
fertilized ovum in the uterus and concludes with development of the major organ
systems at about two months after conception
The Role of Sex Hormones in Sexual Differentiation
Androgens: Males sex hormones
Once genes have done their work and testes develop, they begin to produce
Testosterone: the male’s sex hormone that fosters the development of male sex
characteristics and is connected with sex drive
Each Wolfian duct develops into an epididymis, vas deferens, and seminal
External genitals, including the penis, begin to take shape at about the 8th
week of development under the influence of another androgen,
dihydrotestosterone (DHT)
Prevents the Mullerian ducts from developing into the female duct system
Mullerian inhibiting substance (MIS)
The Mullerian ducts evolve into fallopian tubes, the uterus, and the upper
2/3rd of the vagina
These developments occur even in the absence of female sex hormones
If a fetus with an XY sex chromosomal structure failed to produce
testosterone, it would develop female sexual organs
Descent of the Testes and the Ovaries
The testes and ovaries develop from the slender structures high in the
abdominal cavty
At 10 weeks after conception they have descended so that they are almost
even with the upper edge of the pelvis
Ovaries remain there and later they rotate and descend farther to their adult
position in the pelvis
About 4 months, the testes normally descend into the scrotal sac through the
inguinal canal
Inguinal Canal: a fetal canal that connects the scrotum and the testes, allowing the
latter to descend
Cryptorchidism: the condition defined by undescended testes
Usually treated through surgery or hormonal therapy
Higher risk for cancer of the testes
Sperm production is also impaired because the undescended tests are
subjected to a higher-than-optimal body temperature, causing sterility
Sex Chromosomal Abnormalities

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Kleinfelter Syndrome: a sex chromosomal disorder caused by an extra X sex
1 in 500
Men with this pattern fail to develop appropriate sexondary sex
Have enlarged breasts and poor muscular development, and because they
fail to produce sperm, thet are infertile
Turner Syndrome: a sex chromosomal disorder caused by loss of some X
chromosomal material
1 in 2500 females
May not naturally undergo puberty, so hormone treatments are usually
begun when pubertal changes would start to spur the growth of secondary
sex characteristics
The brain:
Testosterone causes cells in the hypothalamus of male fetuses to become
insensitive the female sex hormone estrogen
In the absence of testosterone, as in female fetuses, the hypothalamus does
develop sensitivity to estrogen
Sensitivity to estrogen is important in the regulation of the menstrual cycle
The hypothalamus detects low levels of estrogen in the blood at the end of
each cycle and initiates a new cycle by stimulating the pituitary gland to
secrete FSH
FSH stimulates estrogen production by the ovaries and the ripening of an
immature follicle in an ovary
Gender Identity
Gender Identity: One’s belief of being male or female
Sex Assignment: the labeling of a newborn as a male or a female, also termed
gender assignment
Most children become aware of their anatomic sex by about 18 months
By 36 months, most children have acquired a firm sense of gender identity
Nature and Nurture in Gender Identity
Gender identity is nearly always consistent with chromosomal gender
Tend to be reared as males or females, in accordance with our anatomic
Intersexual: a person who posses gonads of one gender but external genitalia that
are ambiguous or typical of the other gender (also termed pseudohermaphrodite)
Hermaphrodite: people who possess both ovarian and testicular tissue
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