(M) Lec 5: Reproductive Function (Males) Flashcards
Familiarize yourself with the 6 sources of reproductive hormones
- Gonads (testes and ovaries)
- Hypothalamus
- Pituitary Gland
- Adrenal Gland
- Peripheral non-gladular tissues
- Placenta
What are the 3 sex steroids?
- Androgens
- Estrogens
- Progesterone
Sex Steroids
- The sex steroids are synthesized from ____
- The adrenal ____ synthesizes weak androgens
- Cholesterol (the CPPP ring)
- Cortex
Sex Steroids
What are the 3 weak androgens?
- Dehydroepiandrostenedione (DHEA)
- DHEA sulfate (DHEAS)
- Androstenedione
Note: They have weak affinities to their receptors
Sex Steroids
What are the 3 estrogens?
- Estrone
- Estradiol
- Estriol
Sex Steroids
- The testis converts adrenal androgens into ____
- Through the enzyme, ____, it will become ____ which is more androgenic (10x) than the first product
- The ovary converts testosterone to ____ and androstenedione to ____
- The conversions in the ovary are through the enzyme, ____
- Testosterone
- 5-alpha-reductase; dihydrotestosterone (DHT)
- Estradiol; Estrone
- Aromatase
Sex Steroids
If 5-alpha-reductase is absent, there will be a failure to convert testosterone to dihydrotestosterone which results in?
Conversion into a type of estrogen instead resulting in female features
Sex Steroids
If aromatase is absent, there will be a failure to convert testosterone to estrogens which results in?
Male features on a female patient
Binding Proteins
- 45% of the androgens, testosterone, and estrogens are strongly bound to this
- This transports both progesterone and glucocorticoids
- 50% are loosely bound and will dissociate to become available for interaction with target cells
- Sex Hormone-Binding Globulin (SHBG)
- Corticosteroid-Binding Globulin (CBG)
- Albumin
Binding Proteins
- Makes up 1-2% (or 2-3%) of the hormones
- Are biologically active and can exit the vascular system by diffusion to interact with target cells
Free/Unbound
- Paired, ovoid organs that hang from the inguinal canal by the spermatic cord
- Consists of seminiferous tubules and the interstitium
- Functions in the production of sperm and reproductive steroid hormones
Testes
Testes (analogy)
- Seminiferous tubules are to ____ & ____ cells
- The interstitium is to ____ cells
- Germ Cells and Sertoli Cells
- Leydig Cells
Regulation of Male Reproduction
- The hypothalamus will release the ____ hormone in a ____ pattern
- This will stimulate the anterior pituitary gland to release ____ and ____
- Gonadotropin-Releasing Hormone (GnRH); pulsatile
- Follicle-stimulating Hormone (FSH) and Luteinizing Hormone (LH)
Regulation of Male Reproduction
- The ____ targets the Leydig cells to produce testosterone
- The ____ targets the Sertoli cells to produce androgen-binding proteins (ABP)
- TOF: The testosterone binds to the ABP to aid the survival of sperm cells
- LH
- FSH
- True
Regulation of Male Reproduction
- As spermatogenesis progresses and sperm production increases, the Sertoli cells release ____ which inhibits the release of FSH only (negative feedback)
- With decreased FSH levels, the stimulation of the testes to produce more sperm is ____
- The Sertoli cells also secrete an anti-____ hormone
- Inhibin
- Reduced
- Mullerian
Regulation of Male Reproduction
- When a fetus is already 8 months old, it harbors 2 ducts namely, ____ and ____
- Which duct develops into female internal genitalia?
- Which duct develops into male internal genitalia?
- Paramesonephric Duct and Mesonephric Duct
- Paramesonephric (or Mullerian) Duct
- Mesonephric (or Wolffian) Duct
Regulation of Male Reproduction
- In male embryogenesis, the developing testes produce ____ to cause regression of the ____ ducts and maintain male characteristics
- In female embryogenesis, the absence of ____ results in the development of the ____ ducts to maintain female characteristics
Both numbers (Anti-Mullerian Hormone and Paramesonephric Ducts)
A group of 19-carbon compounds wherein testosterone is the principal hormone of this classification
Androgens
Androgens
- The primary precursor of natural estrogens
- Converted to testosterone and other androgens; also the parent structure of estrone
- Is converted to testosterone
- A metabolite of testosterone but is more potent (most androgenic androgen)
- Dehydroepiandrosterone (DHEA)
- Androstenedione (A4)
- Androstenediol (A5)
- Dihydrotestosterone (DHT)
What makes up the bioavailable testosterone?
Free testosterone + testosterone loosely bound to albumin
Levels of Testosterone
- Testosterone is present as HCG stimulates its release
- There is a little amount which declines at age 1 and becomes absent during the childhood years
- There is a surge stimulated by LH up until adulthood
- Testosterone levels decline as well as spermatogenesis
- Fetal
- Postnatal
- Puberty
- Andropause
Puberty
- This refers to the cell awakening of the adrenal glands wherein it begins secreting sex hormones
- This refers to the maturation of the gonads/enlargement of the genitalia
- An enhanced linear skeletal growth due to increased testosterone
- Adrenarche
- Gonadarche
- Growth Spurt
Puberty
What is the earliest sign of puberty in males and females (2)?
- Males: Testicular enlargement
- Females: Breast enlargment
Puberty
Refers to the failure of the testes to descend due to lack of testosterone
Cryptorchidism
Laboratory Evaluation (Males)
- This test is done if sperm antibodies are suspected
- Can determine cases of oligospermia or azoospermia
- Can be through mixed agglutination reactions and immunobead assays
Semen Analysis
Laboratory Evaluation (Males)
Match the ff. conditions with the accessory gland involved:
1. A pH of >8.0 and decreased ACP
2. Low fructose
3. Neutral alpha glucosidase
4. Low pH, lack of coagulation, and absence of semen odor
A. Ejaculatory duct (obstruction)
B. Prostate (dysfunction)
C. Epididymis
D. Seminal Vesicles
- B. Prostate (dysfunction)
- D. Seminal Vesicles
- C. Epididymis
- A. Ejaculatory duct (obstruction)
Laboratory Evaluation (Males)
A famous example of an image analysis test
Ultrasound
Laboratory Evaluation (Males)
- ↓ Testosterone but ↑ LH and FSH
- ↓ Testosterone and ↓ LH and FSH
- Testicular Failure
- Hypothalamic-Pituitary Disease
Laboratory Evaluation (Males)
The two important tests to determine whether the problems are the testes or the hypothalamus and pituitary gland when hormones are imbalanced
- HCG stimulation test
- Prolactin test
Laboratory Evaluation (Males)
Study the Hormone Analysis Flowchart
Go boo
Laboratory Evaluation (Males)
Testosterone levels demonstrate a circadian pattern wherein it peaks at ____
6:00 to 8:00 AM
Laboratory Evaluation (Males)
- This is the initial screen for testosterone deficiency
- If abnormal, repeat testing on another day
- If results are still abnormal, proceed with further testing
Total Testosterone
Laboratory Evaluation (Males)
- Refers to free testosterone + albumin-bound testosterone
- You can calculate free testosterone from ____ and ____
- Free testosterone is measured using a method called ____
- Bioavailable testosterone
- Total testosterone and SHBG
- Equilibrium dialysis
Laboratory Evaluation (Males)
- High testosterone: ____
- Low testosterone: ____
- High - hypergonadism
- Low - hypogonadism
Laboratory Evaluation (Males)
For FSH and LH Tests:
1. If high, what is the diagnosis?
2. If low, what is the diagnosis?
- High - Testicular disorder
- Low - Hypothalamic or Pituitary disorder
Laboratory Evaluation (Males)
- This test is used to identify if the abnormal FSH and LH levels are of hypothalamic or pituitary origin
- If FSH and LH increase after stimulation, what is the diagnosis?
- If FSH and LH levels do not change after stimulation, what is the diagnosis?
- GnRH Stimulation Test
- Hypothalamic disorder
- Pituitary disorder
Laboratory Evaluation (Males)
In the SHBG test, an increased SHBG indicates what?
Hypogonadism (less bioavailable testosterone can be transported)
Laboratory Evaluation (Males)
In the HCG Stimulation Test, what other hormone is almost the same as HCG to the point that its receptors can respond to it and stimulate Leydig cells?
Luteinizing Hormone (LH)
Laboratory Evaluation (Males)
Match the possible causes with the common abnormal hormone presentations:
- Oligospermia/Azoospermia, ↓ Testosterone, ↑ LH and FSH
- Oligospermia/Azoospermia, ↓ Testosterone, ↓ LH and FSH
- Oligospermia/Azoospermia, Normal Testosterone, LH, and FSH
- Oligospermia/Azoospermia, Normal Testosterone and LH, but ↑ FSH
A. Hypothalamic-Pituitary Disease
B. Primary Gonadal/Testicular Failure
C. Fructose may be present or absent and Spermatogenesis may be normal or abnormal
D. Seminiferous tubule failure/reduced negative feedback inhibition (decreased inhibin)
- B
- A
- C
- D
Male infertility refers to the inability to conceive after ____ year/s of unprotected intercourse
1 year
Types of Male Infertility
- Presents with hypogonadotropic hypogonadism (secondary form)
- Presents with hypergonadotropic hypogonadism (primary form)
- Can be due to obstruction
- Pre-testicular Infertility
- Testicular Infertility (Testicular Failure)
- Post-testicular Infertility
Male Reproductive Abnormalities
If there is hypogonadism (decreased testosterone), what characteristics will fail to develop?
Primary and Secondary MALE characteristics
Reproductive Abnormalities
This type of puberty occurs:
- In females at 8 years old
- In males at 9 years old
Precocious Puberty
Male Reproductive Abnormalities
This kind of rare tumor has the ability to cause a 100x increase in testosterone levels
Testicular Tumor (in Leydig Cells)
Hypergonadotropic Hypogonadism Conditions
Individuals present with an extra chromosome X (47,XXY)
Klinefelter’s Syndrome
Hypergonadotropic Hypogonadism Conditions
Chromosomes are normal but there is a lack of androgen receptors leading to the conversion of testosterone by aromatase into estradiol leading to feminization
Testicular Feminization Syndrome or Androgen Insensitivity Syndrome (AIS)
Hypergonadotropic Hypogonadism Conditions
- An autosomal recessive condition presenting with the inability to convert testosterone into dihydrotestosterone
- People are born with ambiguous genitalia
5-alpha-reductase Deficiency (5-ARD)
Hypergonadotropic Hypogonadism Conditions
Au autosomal dominant disorder leading to dystonia (inability of the muscles to relax) and testicular atrophy
Myotonic Dystrophy
Hypergonadotropic Hypogonadism Conditions
What is the famous example of a testicular injury and infection
Post-pubertal mumps infection (can cause orchitis and permanent testicular injury)
Hypergonadotropic Hypogonadism Conditions
A form of germ cell aplasia (lack of germ cells)
Sertoli cell-only Syndrome
Hypogonadotropic Hypogonadism Conditions
- A deficiency of GnRH in the hypothalamus
- Inherited as an X-linked recessive trait
- Presents with anosmia/hyposmia and red-green color blindness
Note: Anosmia/hyposmia - lack of smell
Kallmann Syndrome
Hypogonadotropic Hypogonadism Conditions
- Can be caused by either a disruption of the GnRH pulsatile secretion or a prolactinoma
- Estrogen promotes the secretion of this hormone
Hyperprolactinemia
