Testicular & Ovarian Function Flashcards
What are the two major functions of reproductive organs?
Gametogenesis and secretion of hormones
Spermatogenesis produces _________ and occurs in _________
Spermatozoa; Sertoli cell in seminiferous tubules
Oogenesis produces _________ and occurs in _________
Ova; ovary
Testosterone in males is produced by
Leydig cells (interstitial cells) in interstitial tissue of the testis
In females, estrogen and progesterone are secreted by
theca and granulosa cells
At the end of mitosis, developing sperm cells are called
Spermatocytes
Human gametes contain how many chromosomes?
23
When does spermatogenesis begin?
At puberty
Germ cells
give rise to gametes
Germ cells exist in
embryonic gonads
Germ cell numbers are increased by
mitosis
Meiosis produces
primary, secondary, and haploid gametes
Mitotic proliferation in males yields
4 Primary spermatocyte from 1 spermatogonium
Primary spermatocytes have how many chromosomes?
46 (diploid, double strands)
The first meiotic division in males produces
Secondary spermatocytes (2 per primary spermatocyte)
Secondary spermatocytes have how many chromosomes?
23 (haploid, single strands)
The second meiotic division in males produces
Spermatids (2 per secondary spermatocyte)
Spermatids have how many chromosomes?
23 (haploid, single strand)
Spermatids give rise to
Spermatozoa
T/F Spermatozoa in the seminiferous tubules are fully mature
False; they have to travel from the seminiferious tubules in the testes out
Spermatozoa have how many chromosomes?
23 (haploid, double strands)
Oogenesis begins
in fetal life
After the first meiotic division, a primary oocyte has become
a secondary oocyte and a polar body
In females, mitotic proliferation of oogonia occurs
prior to birth
At birth, the female has ______ oocytes
Primary
At birth, primary oocytes are arrested in
1st meioitic division
At birth, a female has how many primary oocytes?
~5 million
T/F Female gametogenesis is completed at ovulation
False; the second meiotic division only occurs after fertilization
Female gametogenesis is only completed if
the secondary oocyte is fertilized
At puberty, one primary oocyte
reaches maturity and completes the 1st meiotic division just prior to ovulation
Primary oocytes complete the 1st meiotic division
starting at puberty; just prior to ovulation every month until menopause
What is a polar body?
non-functional oocyte that degenerates
Polar bodies are generated from
primary oocytes (1st meiotic div) and secondary oocytes (2nd meiotic div)
Completion of the 1st meiotic division in females gives rise to
Secondary oocyte
Secondary oocytes have how many chromosomes?
23 (haploid, double strands)
Primary oocytes have how many chromosomes prior to completion of the 1st meiotic division?
46 (diploid, double strands)
Primary oocytes have how many chromosomes following completion of the 1st meiotic division?
23 (diploid, double strands)
Mature ova have how many chromosomes?
23ss (ova) + 23ss (sperm) = 46 chromosomes
T/F Secondary oocytes mature independently to mature ova
False; mature ova only arise AFTER fertilization with sperm
1 primary oocyte gives rise to _______, cf 1 primary spermatocyte gives rise to _______
1 mature ovum; 4 mature sperm
In females, estrogen and progesterone are produced by
follicular cells and the corpus luteum
GnRH from the hypothalamus stimulates
FSH and LH secretion from the anterior pituitary
What are the peptide hormones produced by the gonads in response to LH and FSH?
inhibin and activin
Aromatase converts
testosterone to estradiol
The more biologically active form of testosterone is
dihydrotestosterone, DHT
DHT is produced from testosterone by
5alpha-reductase
In males, the primary target for FSH is
Sertoli cells (spermatogenesis)
In males, the primary target for LH is
Leydig cells (testosterone production)
The scrotum contains
testis, epididymis, and vas deferens
The testis contains
coiled seminiferous tubules
Maturation of sperm occurs in the
epididymis
The vas deferens travels from
the epididymis to the seminal vesicles
Sertoli cells are located
within the seminiferous tubules, surrounding and supporting the sperm
Spermatogenisis occurs in which cells?
Sertoli
What is the role of the interstitial tissues in the STs?
supporting spermatogenesis; Leydig cells produce testosterone and capillaries deliver nutrients/remove wastes
T/F Testosterone secretion from the testes is continuous from birth
False; it is continuous from puberty
What is the pathway of testosterone secretion?
GnRH –> LH –> Leydig cells –> testosterone –> sex characteristics
What is the pathway of spermatocyte maturation?
GnRH –> FSH –> Sertoli cells –> spermatocyte maturation
What is the role of inhibin?
Acts by long and short loop feedback to regulate FSH and testosterone
Spermatogenesis is driven by which hormone?
Testosterone
What are the non-reproductive actions of testosterone?
protein anabolic effects, bone growth, closure of epiphyses, sebaceous gland secretions
What are the components of semen?
Sperm, mucus, water, buffers, nutrients (fructose, citric acid, vitC, carnitine), enzymes, zinc, prostaglandins
What do the STs contribute to semen?
sperm
What do the bulbourethral glands contribute to semen?
mucus (lubricant), water, buffers to neutralize acid in vagina
What does the prostate gland contribute to semen?
buffers to neutralize acid in vagina, nutrients (citric acid), enzymes to clot semen in vagina then liquefy it
What do the seminal vesicles contribute to semen?
nutrients (fructose and vitC), water, enzymes to clot and liequefy semen in vagina, prostaglandins to facilitate smooth muscle contraction and transport of sperm
What does the epididymis contribute to sperm?
Carnitine
In males, FSH acts on ________ to cause ________ and produce _______ which feeds back on ________
Sertoli cells; cause spermatogenesis; produce androgen binding protein and inhibin which negatively feeds back on FSH
Inhibin in males is produced in _____ in response to _____
Sertoli cells; FSH - negatively feeds back on FSH
In males, LH acts on _______ to produce ________ which acts on _________ to stimulate _________
Leydig cells; testosterone; Sertoli cells; spermatogenesis
T/F Spermatogenesis is driven solely by testosterone and can occur in the absence of FSH
False; both testosterone and FSH effects on Sertoli cells are needed to drive spermatogenesis
Testosterone feeds back on
GnRH and LH secretion
What is andropause?
Lower levels of testosterone in ~50% men with ageing; may affect general and reproductive and sexual functions
Menses refers to
sloughing off of the endometrium
What occurs during the proliferative phase of the menstrual cycle?
new uterine lining forms
The menstrual cycle begins at
puberty; interrupted by pregnancy and terminated by menopause
What are the two phases of the menstrual cycle?
Follicular/Proliferative and Luteal/Secretory
The follicular/proliferative phase is dominated by what hormones?
Estrogen
The luteal/secretory phase is dominated by what hormones?
Progesterone and estrogen
Estrogen controls which secondary sex characteristics in females?
Breast development and distribution of body fat
Adrenal androgens control which secondary sex characteristics in females?
Growth of pubic and axillary hair, sex drive
T/F The fallopian tube is physically connected to the uterus and the ovary
False; it is connected to the uterus but NOT the ovary
Endometrium is located
lining the inner uterine wall
What is the role of the endometrium?
Thickens and is shed monthly with menstruation
Myometrium is located
between the endometrium and the outer connective tissue of the uterine wall
What is the function of the myometrium?
Muscle layer that contracts to expel the baby
