Chapter 8.3 Sexual Differentiation Flashcards
What is Sexual differentiation?
Early process in which a fetus begins to develop a male (XY) or female (XX) body and behaviors
How to know whether a baby will be a male or female.
If sperm has an X chromosome it will become female, if it has a Y chromosome it will become male
What is the SRY gene?
It’s the sex determining region on the Y chromosome. Responsible for the development of testes; without it ovaries would form
What is a genital tubercle?
A bump between the legs of an early fetus that can form either a clitoris or a penis
Where does the mullein ducts form in females?
In the fallopian tubes, the uterus, and vagina (wolffian ducts shrink at 8 weeks)
Where does the Wolffian ducts in male form?
In the epididymis, vas deferens, and seminal vesicles (mullein ducts shrink)
What two hormones from the testes masculinize the system
Testosterone and Anti-mullerian hormone
How does Testosterone masculinize the system?
It promotes the development of the wolffian system
How does the Anti-Mullerian masculinize the system?
It induces the regression of the mullerian system
What other structures does testosterone masculinize?
The scrotum and the Penis
What is the 5-alpha-reductase?
It is enzyme that converts testosterone into a more powerful androgen known as Dihydrotestosterone; required for male genitalia masculinization
What is the Turner’s Syndrome
When a person has only one sex chromosome- a single X
Turner’s syndrome
The individual develops as a female but since there are no SRY gene they don’t have any masculinizing effect
What is Congenital adrenal hyperplasia (CAH)?
It where developing females are exposed to excess androgens before birth; new borns have normal ovaries; no testes; and may have intersex appearances
What is intersex?
It is when genitalia are intermediate in form between typical male and typical female genitalia
What is Androgen insensitivity syndrome?
Occurs when an XY fetus has a defective gene for the androgen receptor; embryo tissue doesn’t respond to circulating testosterone, testes remain internal but external tissue develop as female, can form breasts but are infertile(neither ovaries or uterus present)
What is the 5 alpha-reductase deficiency?
When XY(male) lacks the gene responsible for the enzyme converting testosterone to DHT; fetus develop normal male internal reproductive structure but external structure fail to masculinize; at puberty more male development kicks in and increase production of androgens and penis size
What is the organizational effect?
The same steroids that masculinize the developing genitalia also masculinize the brain; permanently alters the brain and behavior
When are hormones effective?
When present during a sensitive period in early development; before or after birth; can also be during puberty
What is sexual dimorphism?
Marked differences in appearance between males and females, also apparent in the brain
What is responsible for sexual dimorphism in the brain?
Androgens
How does sexual dimorphism appear in rats?
The sexual dimorphic nucleus of the POA in the hypothalamus is 5-6 times larger in males than in females; lesions there disrupts ovulatory and copultatory behavior
What is Bulbocavernosus (BC)?
Muscles that surround the base of the penis and inner aged by neurons in the spinal nucleus of the Bulbocavernosus (SNB)
SNB larger in males than in females
