(PSY 450) Chapter 3: Sex Differences in Behavior: Sex Determination and Differentiation.
Terms in this set (18)
What is sex determination?
Occurs when an ovum is either fertilized by a X or Y chromosome to determine chromosomal sex.
Discuss the gender variables that show sexual dimorphism in human and contribute to sex determination.
How do the male and female developmental processes differ in sexual differentiation?
They differ during fertilization of the ovum to determine chromosomal sex. From there, the germinal ridge will either develop into testes or ovaries.
Describe: Female Development
If the SRY gene is not expressed, then the outer part of the ridge (the cortex) will develop into an ovary.
Describe: Male Development
The middle of the ridge (the medulla) will begin to form into testes with the cellular expression of testis determining factor, a protein encoded by the gene SRY
What is the default path of sexual determination? Female or male?
How is masculinization achieved?
Requires testosterone and Mullerian Inhibitory Hormones (MIH) to stimulate the Wolffian Duct System (makes male accessory sex organ penis) while simultaneously regressing Mullerian Duct System to defeminize
How is defeminization achieved?
Normal development of female embryo becomes feminized as the Mullerian Duct System develops while the Wolffian Duct System regresses actively demasculinizing the embryo.
What is the main function of the Wolffian Duct System?
Develops into the male accessory sex organ (penis).
What is the main function of the Mullerian Duct System?
Develops into the female accessory sex organs (fallopian tubes, uterus and cervix)
What is the role of SRY?
(Sex-determining Region on Y chromosome) determines whether germinal ridge (gonads) will develop into testes or ovaries. Determines sexual differentiation.
What is the role of TDF?
TDF is a DNA-binding protein encoded by the SRY gene that is responsible for the initiation of MALE sex determination in humans.
What is the role of MIH (Mullerian Inhibitory Hormone)?
Regresses Mullerian Duct System in male embryos so that they can become defeminized.
What is the role of 5alpha reductase?
The enzyme needed to convert testosterone into DHT. DHT is an androgen necessary for the development of male and female gentital fusing.
What happens if males lack 5alpha reductase?
Undergo incomplete differentiation of the external genitalia.
What happens if females lack 5alpha reductase?
No consequences because normal female development occurs in the absence of sex hormone
Name 1 male anomaly in sex differentiation.
Klinefelter Syndrome (XXY) - considered as males at birth, Y is sufficient for masculinization, -- sterile due to reduced sperm production
Name 1 female anomaly in sex differentiation.
Turner Syndrome (XO) - Ovaries (hypofunctional/dysfunctional).
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