Male Reproductive Anatomy Flashcards
Function of Male repro tract
manufactures and delivers sperm, also synthesizes and secretes androgens
Excurrent Duct System
ducts that bring scrotum from testes to penis (ductus deferens)
Spermatic Cord
Suspends testes in scrotum via inguinal canal, provides pathway for vascular supply (testicular artery + pampiniform plexus), lymph, and ductus deferens
-contributes to regulation for temperature and concentration of testosterone in testes
Pulse Pressure
Significantly reduced when testicular artery enters the spermatic cord so that countercurrent exchange of heat and testosterone can occur
Testicular vein
Surrounds testicular artery as pampiniform plexus
Ductus deferens
sperm transport
Cremaster Muscle
Supports testes and aids in blood flow, somatic muscle that is continuous with internal abdominal oblique muscles
-intermittent contractions causing pumping on pampiniform plexus, improving venous return + aids heat exchange + thermoregulation of testes
Scrotum
Functions as a temperature sensor & regulator, protects and supports testes
Scrotum Skin
Many sympathetic thermosensitive neurons, minimal fat and hair. The neurons signal temp changes to brain signaling sweat glands in scrotum to increase production and respiratory muscles to breathe more
Tunica Dartos
Smooth layer, capable of maintaining strained contractions, changes scrotal location relative to body
Scrotal fascia
supportive layer
Parietal vaginal tunic
prevents adhesions, maintains free floating testes
Scrotal cooling
Essential to maintain proper spermatogenesis and keep sperm viable
Chronic Hypothermia
Caused by high environmental temp, excess fat in scrotum and spermatic cord, inflammation from infections or injury, or frost damage of scrotum
-reduces spermatogenesis, damaged DNA of sperm, reduced fertilization capacity
Testes
Primary reproductive organs that produce sperm, hormones, and tubular fluid (transports sperm)
-vary in size & shape amongst species but share 4 common basic structures
Testicular Capsule
Double layered covering of testes
Visceral vaginal tunic
outer layer of testis
Tunica albuginea
Connective tissue with smooth muscle, directly under visceral tunic
Parenchyma
Functional tissue, 70% of cellular mass in testes
- 2 compartments
Tubular compartment
Seminiferous tubules, further divides
Seminiferous epithelium
Divided into basal and adluminal compartments, germ and sertoli cells
Basal & Adluminal Compartments
Basal - basal lamina to sertoli cells junctions
Adluminal - cell junctions to tubular lumen
Sertoli cells
- somatic “nurse” cells for sperm with TSH and T receptors
- secrete androgen-binding protein, sulfates glycoproteins, transferrin, inhibin and fluids
- positively associated with sperm production
Peritubular cells
Form basal compartment, surround seminiferous tubules and form basement membrane to seperate tubular and interstitial compartments
Blood-testis barrier
Prevents immune cells and Ig from entering adluminal compartment and so prevents autoimmune reactions from destroying germ cells
Leydig cells
Have receptors for LH and produce testosterone
Mediastinum
Central connective tissue core of testis, houses & connects rete testis to efferent ducts
Rete tubules/testis
Small channels through which sperm leaves testes
- drain seminiferous tubules, aided by contraction of testicular capsule and peritubular cells
Excurrent duct system
Site of final maturation, storage, and delivery of spermatozoa
Efferent ducts
Convey newly formed spermatozoa and tubular fluid to epididymal duct, converge to form single duct
Epididymis
Gradual maturation of sperm, acquisition of motility and fertility, storage of sperm (9-14 day transit)
-surrounded by smooth muscle layer which contracts rhythmically to move sperm
Ductus Deferens
Convey stored spermatozoa from tail of epididymis to urethra via smooth muscle contractions until ampulla
Head of epididymis
Spermatozoa are immotile, infertile, and have a proximal cytoplasmic droplet and low disulfide crosslinking
- cytoplasm moves down tail as sperm matures
Body of epididymis
Sperm have some fertility and motility, are capable of binding to oocyte, have a translocating cytoplasmic droplet and have moderate disulfide crosslinking
Tail of epididymis
Sperm have normal fertility and motility, bind oocytes, have lost distal droplet, high degree of crosslinking
Accessory sex glands
Produce seminal plasma, a fluid for delivery and support of sperm
Vesicular glands
Paired glands dorsal-cranial to pelvic urethra, absent in dogs and toms
-vesicular secretions are medium in which sperm is carried
Ampulla
Enlargement of ductus deferens near bladder
- large in stallion, medium in bulls, small or absent in boars
Prostate gland
Close to junction of bladder and pelvic urethra
-only accessory sex gland in dogs
Bulbourethral gland
Paired glands near ischial arch
Penis function
Functions as a copulatory organ and a duct for urine, composed of 3 parts
Base of penis
Attached to ischial arch
Shaft of penis
Main portion of penis and point of attachment for retractor penis muscles
- composed of erectile tissue
Fibroelastic penis
Has a sigmoid flexure (S-shape) of shaft; erections cause increase in length but not width due to non-expandable connective tissue surrounding erectile tissues
Musculocavernous/vascular penis
Changes in length and diameter during erection, contain large areas of erectile tissue
Glans penis
Distal end of penis is highly populated with sensory nerves to stimulate ejaculation
Urethralis mm (UM)
Thick striated muscle that surrounds pelvic urethra and contracts to help movement of sperm to penis urethra
Ischiocavernosus muscle (IcM)
Paired muscle in root of penis (keeps penis in place) that connects pelvic urethra and penis with ischial arch
Bulbospongiosus muscle (BsM)
Overlaps root and extends ventrally, helps empty extrapelvic part of urethra
