Male reproductive system

gamete

sex cells

zygote

fertilized egg

mobile gamete

sprem

gamete containing nutrients for developing zygote

egg or ovum

primary sex organs

gonads: produce gametes

secondary sex organs

organs other than the gonads that are necessary for reproduction (uterus, penis)

secondary sex characteristics

develop at puberty to attract mate (pubic hair, scent glands, voice change)

What determines the sex of a child

interaction between genetics (sperm chromosome) and hormones

When do gonads begin to develop

5-6 weeks GA

male reproductive ducts at gonadal ridge

mesonephric/Wolffian ducts

female reproductive ducts at gonadal ridge

paramesonephric/mullerian ducts

SRY gene name

sex-determining region of Y gene

SRY gene

gene in males that causes development of testes

How does SRY gene work

testis secrete mullerian-inhibiting factor (MIF) causing the degeneration of paramesonephric ducts

how does SRY gene effect the female development

the absence of hormones (androgens) causes female development

Which is the default sex

female

homologous sexual structures

male and female organs that develop from the same embryonic structures

T/F: external genital structure at 8 weeks is the same between genders

T

Beginning structure of external genitals

genital tubercle
pair of urogenital folds
pair of labioscrotal folds

genital tubercle future development

clitoris, penis glans

urogenital folds future development

enclose urethra
form labia minora

labioscrotal folds future development

scrotum
labia majora

When do genitals become distinctly male/female

12 weeks GA

inguinal canal

passageway for testes during descent from abdominal cavity to scrotum

gubernaculum

CT that guides testicular descent

inguinal rings

bilateral oblique passageway in the anterior abdominal wall that testes must pass on descent

cryptorchidism

undescended testicle

Why do testes descend

thermoregulation for sperm production

idea temperature for sperm production

2-3 degrees centigrade below core body temperature

What structures help maintain temperature in scrotum

cremaster muscle
dartos muscle
pampiniform plexus

cremaster muscle

pulls testes close to body

dartos muscle

lifts scrotum upward

pampiniform plexus

veins ascending near testicular artery that acts as a countercurrent heat exchanger to cool arterial blood entering testis

tunica albuginea

white fibrous capsule on testes that penetrates to create lobules

where is sperm produced

seminiferous tubules

Where is testosterone produced?

interstitial (Leydig) cells

structure of teste

-tunica albuginea surrounds and separates testis into lobules
-lobules contain 1-3 seminiferous tubules
-Interstitial cells lay between seminiferous tubules

germinal epithelium role

several layers of germ cells in process of becoming sperm

germinal epithelium location

line the lumen of seminiferous tubules

sustentacular (Sertoli) cells functions

-protect/promote germ cells
-provide nutrients/waste removal/growth factor for germ cells
-secrete inhibin
-form BTB

Why is O2 supply in testicular artery low

sperm develop in hypoxic environment to mimic uterus
-develop larger mitochondria

flow of sperm

efferent ductules > epididymis > vas deferens > ejaculatory duct

efferent ductules

collect sperm from rete testes and transport it to epididymis

epididymis

site of sperm maturation and storage

How long are sperm fertile for in the epididymis

60 days

ductus deferens (vas deferens)

muscular tube in spermatic cord that ends by uniting with seminal vesicle duct

ejaculatory duct

DUCT FORMED FROM DUCTUS DEFERENS AND SAMINAL VASICLE that passes through the prostate

where does the ejaculatory duct empty

prostatic urethra

urethra

tube leading from the urinary bladder to distal end of penis

urethra function

passageway for urine and male reproductive fluids

urethra parts

prostatic, membranous, spongy/penile

seminal vesicles

pair of glands that join with each vas deferens to empty into ejaculatory duct

seminal vesicles secretions

fibrinogen, fructose, and prostaglandins

what percentage of semen is produced by seminal vesivles

60

prostate gland

surrounds urethra and ejaculatory duct and in just inferior to bladder

What percentage of semen is made by prostate gland

30

prostate gland secretions

milky, thin secretions containing citric acid

bulbourethral glands (Cowper's glands) secretions and role

mucous
-neutralize pH of vagina and urine

what percentage of semen is made by bulbourethral glands

5

how much sperm is typically in semen

50-150 mill/ml

What is considered the lowest sperm count before being infertile

20 mill/ml

penis functions

urination, serves as vehicle for injecting sperm into vagina

WHat are the 3 columns of erectile tissue

2 corpora cavernosa
1 corpus spongiosum

glans penis

enlargement of corpus spongiosum

circumcision

surgical removal of the prepuce (foreskin)

another name for forskin

prepuce

What begins development again after birth

surge of pituitary gonadotropins

When does development begin again for girls

8-10

When does development begin again for boys

10-12

Adolescence

onset of gonadotropin secretion and reproductive development until a person attains full adult height

puberty onset for girls

12

puberty onset for boys

13

Brain testicular axis

- Hypothalamus produces GnRH
- Stimulates anterior pituitary (gonadotrope cells) to secrete LH and FSH

LH stimulates:

The intestinal cells to produce testosterone

FSH stimulates:

spermatogenesis

Effects of testosterone

-stimulates spermatogenesis
-inhibits GnRH
-development of 2nd sexual organs
-growth spurt
-erythropoiesis
-libido

inhibin role

inhibits FSH secretion

Sperm morphology

head and tail

parts of sperm head

nucleus, acrosome, basal body

acrosome

hat of sperm that has enzymes to penetrate egg

parts of sperm tail

middle piece, principal piece, terminal piece

Where is the mitochondria in sperm located

midpiece

life expectancy of sperm in female reproductive tract

48 hours

requirements for sperm motility

elevated pH and energy source

What system triggers penial erection

parasympathetic

What is secreted to trigger erection

NO

What nervous system controls emission

sympathetic nervous system

stages of ejaculation

emission and expulsion

expulsion stage

semen in urethra activated muscular contractions

Sympathetic effects on erection

reduce blood flow causing penis to soften

primordial germ cells

stem cells destined to become sperm

spermatogonia location

lie along periphery of seminiferous tubule outside of the BTB

What 2 cells are created by spermatogonia mitosis

Type A: remain outside BTB and multiply
Type B: Migrate past BTB and differentiate

2 types of type B spermatogonia

primary spermatocytes and secondary spermatocytes

primary spermatocytes

pass through BTB and move into lumen of tubule

secondary spermatocytes

primary spermatocytes that move outside the BTB and undergoes meriosis I

What stage of spermatogenesis ends DNA replication

secondary spermatocytes

Meiosis II of spermatogenesis

secondary spermatocytes split into 4 haploid cells (spermatids)

final stage of spermatogenesis (spermiogenesis)

development of haploid spermatids into sperm

process of spermiogenesis

-spermatids transform into the elongated form
-acrosome forms atop nucleus
-flagellum develops
-mitochondria multiply