Sexual Differentiation Flashcards
Name the four levels in which sex can be defined.
- Chromosomal
- Gonadal
- Somatic (physical appearance) - external and internal
- Psychic
What is 45, X? This is characterized by _____ dysgenesis.
Turner syndrome - gonadal dysgenesis
What is 47, XXY? This is characterized by _____ _______ dysgenesis.
Klinefelter syndrome - seminiferous tubule dysgenesis
Gonads are initially ________ and develop from the primitive gonadal streak on the genital ______.
initially indifferent and develop from the primitive gonadal streak on the genital ridge.
Ovaries develop from the ________ of the indifferent gonad and testis develop from the _______ of the indifferent gonad in week ___ of embryonic development.
ovaries from the cortex, testis from the medulla in week 6
Embryonic ovaries produce no estrogens, while testis produce ________ and _____ to control further masculinization.
testis produce testosterone and MIS
The first thing that happens in differentiation from indifferent –> male is the SRY gene activates a transcription factor called _____ that activates transcription of testis-forming genes.
Testis-determining factor (TDF)
Which two testicular cell types are involved in generating products that aid in further sexual differentiation?
Leydig cells and sertoli cells.
What hormone do leydig cells primarily make that plays a role in early sexual differentiation? What does this hormone do?
Leydig cells make testosterone which acts on the Wolffian duct system to form the epididymis, seminal vesicles, and vas defrens.
Testosterone is also converted to DHT, which acts to form the penis, prostate, and urethra.
What important substance do sertoli cells primarily release that plays a role in early sexual differentiation? What does this substance do?
Sertoli cells make Mullerian Inhibiting Substance/Factor which acts on the Mullerian duct, resulting in inhibition of the formation of the uterus and fallopian tubes.
What is the most common enzyme deficiency that results in formation of ambiguous genitalia? Describe what happens.
21-hydroxylase deficiency blocks downstream formation of cortisol and aldosterone and results in the build up of products that are shunted to an androgen (testosterone, DHT) forming pathway. This results in masculinization of external structures (but not internal structures, that is done with MIS).
Name a specific example of congenital adrenal hyperplasia.
21-hydroxylase deficiency
Name a specific example of congenital adrenal hyperplasia that can result in incomplete masculinization of genetic males.
3-beta hydroxysteroid dehydrogenase deficiency results in the ability to make only DHEA which is a very weak androgen
The age of puberty has been _________ in the U.S. over the past 175 years.
decreasing
Average puberty onset age for males in the U.S. is _____ and for female African Americans it is ______ and ______ for female caucasians.
Males: 9-10 years old
AA females: 7-8
Caucasian females: 8-9
Delayed puberty workups are indicated if females have not had menses by age _____ and if males have absent testicular development by age _____.
females by age 13, males by age 14
What are the five steps of male puberty?
- Pre-adolescence
- Beginning of testicular enlargement
- Penile enlargement
- Growth of the glans penis
- Completion into the appearance of adult genitalia
What is the method of pubertal developmental staging called?
Tanner Staging
The hypothalamus releases _____, which acts on the anterior pituitary, causing release of _____ and ____ that acts on the gonads.
hypothalamus releases GnRH and AP releases LH, FSH
In males, LH acts on ______ cells, which make _______ that help sustain ______ cells.
LH acts on Leydig cells, which make androgens that help sustain Sertoli cells.
In males, FSH acts on ______ cells, which help sperm grow. These cells also make _____ and _____.
FSH acts on Sertoli cells and they make ABP and inhibin
Androgens in males are produced primarily by the testis but also by ______, ______, and _____.
adrenal, adipose, and skin
List the potency of the male androgens from most to least potent.
DHT > testosterone»_space; androstendione > DHEA
Androgens have the negative effect of ______ enlargement in males 50 years and older and also contribute to male-pattern baldness.
prostate
What can exogenous anabolic steroids do to testicles?
Induce atrophy by altering androgen synthesis.
What are the female stages of puberty?
- Telarche (breast development)
- Pubarche (pubic hair)
- Menarche (menstruation)
Initially, menstrual periods are _____ in length. They are also usually _______ and the cycles are _______.
variable in length, anovulatory, and irregular in cycle.
In females, LH acts on _____ cells. FSH acts on _____ cells.
LH acts on theca cells, FSH acts on granulosa cells.
What do theca cells make and what do those things do?
Theca cells make androgens and progestins. Androgens promote the health of granulosa cells. Progestins act on the uterus to regulate the uterine cycle.
What do granulosa cells make and what do those things do?
Granulosa cells make inhibins, activins, progestins, and estrogens. Inhibins feedback on the AP (negative) and activins positively feedback on the AP. Progestins and estrogens act on the reproductive tract and both also feedback on the AP, hypothalamus, and CNS.
GnRH release is ______.
pulsatile
At around age 50, FSH and LH levels ______ in females.
increase
Describe the three categories of abnormal puberty development.
- Precocious pseudopuberty is when there is early development of secondary sex characteristics due to abnormal exposure of androgen to immature males or estrogen to immature females. NO gametogenesis occurs!
- True precocious puberty is early but otherwise normal early puberty due to normal physiologic processes.
- Constitutional precocious puberty: no underlying cause. More common in females.
Proteases are released during the acrosome reaction to facilitate penetration of the ovum. Shortly after, _____ is released which mediates fusion to the ovum membrane.
fertilin
The blastocyst secretes hCG, which acts as an ___________ agent, has growth-promoting activity and acts as an _______ growth factor that promotes placental development.
hCG is an immunosuppressive agent and acts as an autocrine growth factor
Name five things that the placenta synthesizes.
- hCG
- Human chorionic somatomammotrophins
- Peptide hormones
- Neuropeptides
- Placental variants of hypothalamic hormones
Can insulin, IGF, and T3 cross the placenta?
Nope
Describe the maternal-placental-fetal unit.
The mother supplies cholesterol to the placenta.
The placenta turns cholesterol into pregnenolone and progesterone, both of which are transferred to the fetus.
The fetal adrenals turn pregnenolone into DHEAS and progesterone into cortisol and cortisone. DHEAS is converted to 16-OHDHEAS. Some of the DHEAS and 16-OHDHEAS is also transferred back to the placenta.
In the placenta DHEAS is converted to estradiol, 16-OHDHEAS is converted to estriol. These are estrogens and these also transfer to the mother.
