Male Reproductive System Flashcards
Genitalia
- Sex organs
- divided into:
- primary sex organs
- accessory sex organs
Primary Sex Organs
- AKA Gonads
- “seeds”
- Produce gametes (sex cells)
- Produce sex hormones, functioning as endocrine glands
- testes in males: produce sperm
- ovaries in females: produce ovum (egg)
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accessory sex organs
- all other genitalia in both sexes
- includes:
- internal glands and ducts
- external genitalia
Scrotum
- Pouch
- a sac of skin and superficial fascia
- hangs inferiorly external of the abdominopelvic cavity at the root of the penis
- contains testes/testicles
- septum at the midline dividest scrotum into to compartments
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Dartos Muscle
- a layer of smooth muscle in the superficial fascia
- responsible for wrinkling the scrotal skin (in cold conditions)
- increases thickness
- reduces heat loss
cremaster muscles
- bands of skeletal muscle that extend inferiorly from the internal oblique muscles of the trunk
- responsible for elevating the testes
- relax in hot conditions
width and length of testes
- average 2.5 cm (1 inch) in width
- average 4 cm in height
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Tunica Vaginalis
(Anatomy of Teste)
- a serous sac inside the scrotum
- each teste is posterior to and partially enclosed by this
- develops as an out pocketing of abdominal peritoneal cavity
- Consists of:
- superficial parietal layer
- intermediate cavity containing serous fluid
- visceral layer that hugs the surface of the testes
- Keep testes retroperitoneal
tunica albuginea
(Anatomy of Teste)
- Just deep to the visceral layer of the tinica vaginalis
- “white coat”
- fibrous capsule of the testes
- septal extensions project inward to divide the testes into 250-300 wedge-shaped compartments called lobules
Lobules
(Anatomy of Teste)
- 250-300 wedge shaped compartments in the testes
- each contain 1-4 seminiferous tubules
seminiferous tubules
(Anatomy of Teste)
- 1-4 coiled tubules in each lobule
- the actual sperm factories
- most are looped like hairpins
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straight tubule
(Anatomy of Teste)
- convergence of seminiferous tubules of each lobule, posteriorly
- conveys sperm into rete testes
rete testes
(Anatomy of Teste)
- “network of testes”
- lined by simple cuboidal epithelium
- a complex network of tiny branching tubes.
- lies in the mediastinum testis
- region of dense connective tissue
- posterior part of testes
- sperm leave here through efferent ductules
pampiniform plexus
(Anatomy of Teste)
- venous network in the scrotum
- from which testicular veins arise
- “tendril shaped”
- surround testicular arteries like climbing vines
- absorb heat from arterial blood
- cooling it before it enters the testes
- keeping testes cool
- called countercurrent heat exchange
innervation of testes
(Anatomy of Teste)
- innervated by both divisions of the autonomic nervous system
- abundant visceral sensory nerves transmit impulses
- results in agonizing pain and nausea when testes are hit forcefully
varicocele
(Anatomy of Teste)
- a varicose vein in the pampiniform plexus
- disrupts venous return from the testicles
- found in 15% of men in gen pop
- found in 40% of men being evaluated for fertility treatments
- may cause sperm abnormalites
spermatogenisis
(seminiferous tubules and spermatogenesis)
- the process of sperm formation
- begins at puberty
- an adult will form 400 million sperm/day
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spermatogonia
- the stem cells from which sperm cells are formed
- “sperm seed”
- lie peripherally on the epithelial basal lamina
- produce:
-
primary and secondary **
- spermatocytes
- spermatids
- spermatozoa
-
primary and secondary **
3 stages of spermatogenisis
- Formation of Spermatocytes
- Meiosis
- Spermiogenisis
Stage 1: Formation of spermatocytes
(Spermatogenisis)
- Spermatogenia divide by mitosis
- each division produces two daughter cells
- Type A: remain at basal lamina to maintain germ cell line* *
- *Type B: *move toward lumen to become primary spermatocytes
Stage 2: Meiosis
(Spermatogenesis)
- “a lessening”
- cell division that reduces the number of chromosomes found in typical body cells
- essential part of gamete formation in both sexes
- Meiosis I:
- primary spermatocytes produce 2 secondary spermatocytes
- Meiosis II
- secondary spermatocyte produce 2 small cells called spermatids
Stage 3: Spermiogenesis
(Spermatogenesis)
- spermatids differentiate into sperm (Spermatozoon)
- fashions tail, sheds cytoplasm
- sperm detaches from seminiferous tubule and enters lumen
- do not gain ability to swim until after they leave testes
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spermatozoon
- “animal seed”
- new sperm cell
- has head, tail and midpiece
Head of spermatozoon
- flat, sunflower seed-shaped nuclueus which contains:
- condensed chromatin
- helmetlike *acrosome *
Acrosome
Head of spermatozoon
- “tip piece”
- a lysosome-like vesicle made by the Golgi apparatus
- contains digestive enzymes that enable sperm to penetrate an egg
midpiece of spermatozoon
- thickened first part of tail
- contains mitochondria spiraled tightly around the core of the tail
- provide whiplike movements of the tail that propel the sperm through the reproductive tract of the female
tail of spermatozoon
- long, elaborate flagellum
- motile cytoskeleton has grown out from a centiole near nucleus
Hormones that control spermatogenesis
- follicle-stimulating hormone (FSH)
- from anterior part of pituitart gland
- testosterone
- primary male sex hormone produced by testes
Sustentacular Cells
(seminiferous tubules and spermatogenesis)
- surround spermatogenic cells
- AKA sertoli cells
- extend from the basal lamina to the lumen of the seminiferous tubule
- bound to each other by tight junctions on lateral membranes
- divide the seminiferous tubule into two compartments:
- basal compartment
- adluminal compartment
basal compartment
of seminiferous tubule
- extends from the basal lamina to the tight junctions of sustentacular cells
- contains spermatogonia and earliest spermatocytes
Adluminal Compartment
of the seminiferous tubule
- “near the lumen”
- lies internal to the tight junctions of sustentacular cells
- includes more advanced spermatogenic cells and the lumen of the tubule
Blood-testis barrier
- tight junctions of the sustentacular cells
- prevents the escape of membrane antigens of differentiating sperm through the basal lamina and into the bloodstream
- they’d activate the immune system
- immune system’s response would destroy gametes and produce sterility
- they’d activate the immune system
- must pass through adluminal compartment
Ways sustentacular cells assist sperm production
- convey nutrients to spermatogenic cells
- move these cells toward the tubule lumen
- phagocytize the cytoplasm that is shed as spermatids become sperm
- secrete *testicular fluid *
- secrete *adrogen-binding protein *
- secrete inhibin
testicular fluid
- secreted from sustentacular cells
- secreted into the tubule lumen
- pressure of fluid pushes sperm through tubule and out of testes
androgen-binding protein
- secreted from sustentacular cells
- concentrates male sex hormone (testosterone) near the spermatogenic cells
- testosterone stimulates the spermatogenesis
inhibin
- hormone secreted by sustentacular cells
- slows the rate of sperm production (when necessary)
- inhibits FSH secretion from pituitary gland
Myoid Cells
(seminiferous tubules and spermatogenesis)
- smooth-muscle-like cells
- surround the seminiferous tubules in several layers
- contract rhythmically
- may help squeeze sperm and testicular fluid through the tubules and out of the testis
interstitial cells
(seminiferous tubules and spermatogenesis)
- leydig cells
- spherical/polygon-shaped cells
- found in clusters in the loose connective tissue between seminiferous tubules
- make and secrete androgens (male sex hormone–testosterone being the main one)
androgens
- male sex hormone
- made and secreted by interstitial(leydig) cells
- Main type: Testosterone
- circulates through the body and maintains all male sex characteristics and sex organs
- all male genitalia atrophy if testes (and testosterone) are removed
Luteinizing Hormone
LH
- a hormone from the anterior part of the pituitary gland
- controlls secretion of testosterone by interstitial cells