wk 13, lec 1 Flashcards
Efferent ductules, vas deferens, ejaculatory duct, urethra
fucntion
move spermatozoa, fluid reasborption
epididymis function
H+ secretion, acidify luminal fluid
incapacitate spermatozoa; glycoconjugation
resevoir for mature sperm
phagocytosis of aging sperm
seminal vesicle function
secrete and store fructose rich product (energy substrate for sperm), prostaglandins, ascorbic acid, fibrinogen like and thrombin like proteins
prostate function
secrete and store fluid rich in acid phosphatase and protease
prostate specific antigen (PSA) to dissolute seminal fluid coagulation following ejaculation
bulbourethral (Cowper) glands function
secrete mucus (lubricant) into urethra upon arousal
cells in the testes
sertoli cells
leydig cells
germ cells
Sertoli cells functions
supports developing germ cells in spermatogenesis
create barrier to seperate germ cells from bloodstream (BTB)
phagocytose apoptotic germ cells to maintain quality of delveoping sperm
provides AMH during fetal development; helps to regress mullein ducts and differentiate male reproductive structures
Sertoli cells provide which hormone in fetal development
AMH
leydig cells -which hormones?
make testosterone
respond to LH
leydig cells
make and secrete testosterone
response to LH from anterior pituitary
regulate male secondary sexual characteristics
support spermatogenesis via andogenic environment
sexual function
germ cells are precursors of
spermatozoa
germ cells undergo devleopment in
spermatogenesis
germ cells include
spermatogonia, spermatocytes,
spermatids, and spermatozoa.
blood testis barrier
protect developing germ cells from immune attack
special envo for spermatogenesis
spermatogenesis
germ cell – spermatozoa
@ puberty
compartmentalized via blood testes barrier
FSH regulated
what hormone regulates spermatogenesis
FSH
controllers of spermatogenesis
controlled by FSH and testosterone
increase spermatogonia proliferation
increase sertoli angdrogen binding protein
4 stages of spermatogenesis
- proliferation of spermatogonia (stem cells)
- meiosis: spermatocytes –> spermatids (23 chromosomes)
- speriogenesis: maturation and development –> spermatozoa (sperm)
- spermiation: release of mature sperm
spermatogenesis
1. Proliferation of Spermatogonia
Gives Rise to Spermatocytes
stem cells (spermatogenonia) in seminiferous tubule
originate at puberty (gonocytes proliferate)
1 or 2 divisons of spermatogonia to maintain stem cell pool
some stay in resting pool and other proliferate to give rise to primary spermatocytes
resting spermatogonia are dormant then join new proliferation cycle
–> always residual pool in testis to make sperm
spermatogenesis
2 & 3. Meiosis of Spermatocytes
Yields Spermatids
primary spermatocytes undergo 2 divisions
meiosis 1: makes 2 seocndary spermatocytes
meiosis 2: make spermatids (haploid cells; 23 chromosomes)
spermatogenesis
4. Spermiogenesis
maturation of spermatids into spermatozoa (via nuclear and cytoplasmic changes)
- spermatid condensation of nuclear material
- formation of the acrosome
- repositioning of the spermatid to allow formation and elongation of tail structures
- mitochondrial spiral formation
- removal of extraneous cytoplasm
acrosome development in sperm for
secretory vesicle - has enzymes for mucus penetration and fertilization
mitochondrial sheath around flagellum of sperm for
provide energy (fructose derived ATP) for flagellar movement
Spermatogonia, spermatocytes,
spermatids, and spermatozoa
spermatogonia (germ cells under mitosis)
spermatocytes (diploid germ cells undergo meiosis)
spermatids (haploid via meiosis II)
spermatozoa (mature gametes that can be fertilized)
factors effecting spermatogeneiss
temperature
radiation
chemical expsoures
diet
exercise
stress
hormonal imabalnce
genetic disorders
infections
hormonal regulation of speramtogensis
hypothalamus? AP? testes?
GnRH in hypothalamus
FSH and LH in anteriori pituitary
testosterone and inhibin B in testes
FSH binds which cells in testes
Sertoli cells –> activated –> proliferate and differentiate of spermatogonia
negative feedback of FSH via
inhibin in Sertoli cells when sperm production at optimal levels
LH acts on
leydig cells
LH vs FSH act on
LH- leydig cells
FSH- sertoli cells
LH impact on sperm
bind leydig cells which make testosterone
testosterone needed for spermatogenesis and secondary sex characteristics
testosteorne functions
spermatogenesis
libido
erectile function
secondary sex characteristics
hypothalamic-pituitary-gonadal (HPG) axis regulates testosterone
inhibits GnRH and LH secretion when high
stimulates FSH and LH secretion when levels are low
modulators of spermatogenesis
growth factors: IGF1, FGF, ECF
cytokines (tissue develop): ILs, TNFa
paracrine/autocrine signals: retinoid acid and prostaglandins;
micronutrients for sperm
Zinc, selenium, and vitamin D needed in
spermatogenesis, sperm motility, and DNA integrity
scrotal pain
many causes
pt history: onset, pain location , after sex? at night? trauma?
sx: fever? N/V? discharge?
causes of scrotal pain
non acute w mass: cyst, cancer
non acute w no mass: prostatitis, epipdymzitis
acute w trauma: testicular rupture or torsion
acute >20yoa, fever, ab pain: appendicitis
acute >20yoa, fever, dysuria: epidymsitis, prostatitis
acute <20yoa, sudden: testicular torsion
ETCCC chart on slide 34
testosterone–> estradiol via what enzyme and whats the effect
CYP19 aromatase
acts on bone; epiphyseal closure, icnreased density
libido
testosterone–> dihydrotestosterone via what enzyme and whats the effect
5 alpha reductase
external genitialia: differentiation during gestation, maturation during puberty, adulthood prostatic disease
hair follicles: increase growth during puberty
testosterone act on androgen receptors; what impact
internal genitlaia: wolfing development during gestation
skeletal muscle: increased mass and strength during puberty
erythropoiesis, bone growth
which cells make testosterone
leydig cells
what stimulates leydig cells to make testosterone
LH
testosterone production rhythms
circadian- peak in early morning
hypogonadiam
low testosterone
Causes impaired spermatogenesis and
dysfunction of male reproductive system
decreased libido, erectile
dysfunction, erectile dysfunction, infertility, and
fatigue, decreased bone density, increased body fat
primary (hypergonadotrophic) vs secondary (hypogonadotropic) hypogonadism
primary: testicular failure;
–> genetic disorders (i.e.
Klinefelter’s) testicular trauma,
chemotherapy, radiation therapy, or
infections
secondary: from dysfunction of hypothalamus or pituitary (decreased GnRH, LH, FSH)
–>pituitary tumours,
hypothalamic dysfunction, head
trauma, and certain medications
hormones in primary vs secondary hypogonadism
primary: increase GnRH, LH, FSH and decrease sex steroids (estrogen, progesterone, testosterone)
secondary: primary: decrease GnRH, LH, FSH and decrease sex steroids (estrogen, progesterone, testosterone)
testosterone and metabolic function
low T has central adiposity
low T has insulin resistnace
high T to increase muscle mass
T changes gene expression, improves glucose uptake, promotes lipolysis
TRT to help with obesity and insulin
testosterone to make male sex differentation
Male Genitalia: T stimulates the
differentiation of the genital tubercle into the penis,
the urogenital folds into the penile urethra, and the
labioscrotal swellings into the scrotum
Wolffian Duct Development: T induces the
differentiation and development of the Wolffian ducts
into the epididymis, vas deferens, and seminal
vesicles. DHT is particularly important for the
differentiation of the prostate gland
Androgen Insensitivity Syndrome (AIS):
XY chromosomes but external genitialia appear female or ambiguous despite having testes internally
Congenital Adrenal Hyperplasia (CAH):
overproduce adrenal androgens –> virilization of external genitialia in females
5-alpha-reductase Deficiency
cant convert testosterone into DHT –> ambiguous genitalia at birth that may virile during puberty
FSH acts on
Sertoli cells –> make cells produce growth factors and proteins for sperm maturation
testostostone made by and acts on
made by leydig cells (spermatogenesis)
act on Sertoli cells and germ cells for proliferation, differentiation, and maturation of
sperm cells
sperm cell development stages and impact of androgens
spermatogonial phase: androgens to proliferate and maintain spermatogonia (stem cells for sperm)
meiotic phase: androgens for divison and progression of spermatocytes to spermatids
spermiogenesis: androgen to regulate gene expression and protein synthesis (i.e. nuclear condensation, acrosome formation, tail elongation)
testosterone biosynthesis pathway
cholesterol –> pregnenolone –> progesterone –> 17alpha-hydroxyprogesterone –> androstenedione –> testosterone –> DHT (via 5a-reductase)
