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PSYB64H3 (201)
Chapter 10

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Zachariah Campbell

PSYB64Chapter 10 Sexual BehaviorSexual DevelopmentThe fetus is initially undifferentiated in regard to sex without exposure to male hormones all babies would be born with female physical appearance and behaviorSex Chromosome Abnormalities Turner Syndromea condition in which a child receives only a single X chromosome from the parent o From this we have learned that a single X chromosome carries enough genetic material to produce a person who is normal but because heshe lacks the second chromosome the person faces difficulties in growth fertility hormone production risk of diabetes osteoporosis and cardiovascular disease o Individuals with this disease have normal female genitalia but the ovaries develop abnormallyUnidentified regions on the X chromosome are responsible for development of ovaries but having only 1 X chromosome interferes in this processIn most cases the ovaries dont produce either the ova or normal levels of female hormones which leads to infertility but when the X chromosome is missing in some but not all cells women may be fertileWomen with Turner syndrome are short and may have increased skin folds at the neck intelligence is normal but specific deficits in spatial relationships and memory can occur Klinefelter Syndromeit is the most common genetic abnormality related to sex chromosomes and features an XXY genotype o These individuals are male but experience reduced fertility and require hormone treatment at puberty to promote the development of secondary make sex characteristics and to inhibit female characteristics o The process of Xinactivation is also disturbed leading to other symptoms o It is associated with normal intelligence along with cognitive deficits and social awkwardness o Delayed reduced verbal skills lefthandedness brain lateralization is affected along with localization of specific functions An XYY genotype has also been identified 11000 births in which boys appear to be physically within typical limits although they tend to be somewhat taller and leaner suffer from acne and have a higher risk for minor injuries o IQ scores are lower than average o The men are fertile but they have a higher chance of producing sperm with sex chromosome abnormalitiesA report has suggested that individuals with XYY genotype were overrepresented in prisonThree Stages of Prenatal Development3 distinct phases of development o Development of gonads o Development of internal organs o Development of external genitaliaNormally all 3 processes occurcongruently to produce an unambiguous male or female but in a rare condition called intersex elements of both male and female development occurs in the same fetus The Development of the Gonads o Up until 6 weeks of conception male and female fetuses have the same gonads with the capacity to either develop into ovaries or testes o After the 6 weeks the sex determining region of the Y chromosome SRY is expressed in male embryos o SRY encodes the Testisdetermining factor protein which causes the gonads to develop into testes o In female embryos there is no SRY gene or testisdetermining factor protein so alternate genes guide the formation of the ovaries Differentiation of the Internal Organs rdo In about the 3 month of development both males and females fetuses possess a male Wolffian system and a female Mullerian system o In males the Wolffian system develops into seminal vesicles vas deferens and the prostate o In females the Mullerian system develops into the uterus upper portion of vagina and fallopian tubes rdo During the 3 month the males testes begin to secrete testosterone promotes development of Wolffian system and antiMullerian hormone initiates degeneration of the Mullerian system o In the female fetus no additional hormones are required for development the ovaries are not active during fetal development the Mullerian system will just develop in the typical female direction but the nonfunctional remnants of the Wolffian system still remain throughout a womans life o Androgen insensitivity syndrome AIS is a defective gene that produces abnormal androgen receptors and disrupts the normal development of the Wolffian system in males o In AIS the fetuss tissues are blind to the presence of androgenso Fetuses with AIS have an XY genotype and normal testes and the testes release androgens and the antiMullerian hormone in a normal manner but the lack of functional androgen receptors prevents the development of the Wolffian system o The antiMullerian hormone still works normally so the female Mullerian system also fails to develop o Adult individuals with AIS are infertile their external appearance is quite typically female o Individuals with AIS are genetic males but typically have female appearance and strong female gender identities o AIS might be an advantage for women in sports Development of the External Genitalia tho Happens during the 6 week after conception o No hormonal activity is required in order to develop female external genitaliao 5alphadihydrotestosterone must be recognized by receptor sites for the male external genitalia to develop normally
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