Male Reproductive System Flashcards
Male reproductive functions
- production of male gametes
- Production of male sex hormone testosterone
- Introduction of male gametes into the female reproductive organs
- Production of other hormones such as AMH in male embryo and ABP and inhibin in adult
Male reproductive system
Testis Epididymis Ductus deferens Accessory sex glands: vesicular glands, prostate, butbourethral glands External genitalia/penis
Testis
Site of spermatogenesis
Site of production of sex hormone
Surrounded by a tunic (tunics)
Parenchyma is composed of seminiferous tubules lined with spermatogenic epithelium
Interstitiel contains Leydig cells –> testosterone
Testicular tunics
Surrounded by parietal and visceral vaginal tunics and tunica albuginea
Vaginal tunic is composed of mesothelium and a connective tissue layer (outpouching of peritoneum)
Vaginal tunic has a parietal and visceral component. Upon removal of testis the parietal component blends and is attached to the CT of the scrotum (remains in animal) and the visceral layer surrounds the testis and the epididymis (is removed)
Tunica albuginea is a capsule of dense CT which lies under the visceral vaginal tunic-continuous with CT septa that separate seminiferous tubules and the mediastinum
Seminiferous tubules
Highly convoluted, tortuous loops
Lined by spermatogenic epithelium
Interstitial cells known as Leydig cells are located between tubules
Spermatogenic epithelium is surrounded by lamina propria of collagen and elastic fibers
Spermatogenic cells
Spermatozoa
Sertoli cells
Myoid cells
Spermatogenic cells
Progressive maturation through spermatogonia A and B, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa
Spermatozoa
in lumen of seminiferous tubules; are immotile
Sertoli cells
Line the tubules; support the spermatogenic cells
Tall cells that extend from basement membrane to the lumen of the tubule
Have pale oval to triangular nuclei and indistinct cell borders
Myoid cells
Located outside basement membrane of each tubule. Function is to move spermatozoa out of tubules
Spermatocyte-sertoli interaction
- Mitotic divisions of spermatogonia produce new germ cell and a committed cell (primary spermatocyte)
- First meiotic division produces secondary spermatocytes (haploid)
- second meiotic division originates with secondary spermatocytes and produces spermatids
- spermatogenesis begins with spermatids and results in morphological changes needed to form motile sperm
Sertoli cells -functions
Support, protect, nourish spermatogenic cells
Secrete supporting seminiferous tubular fluid
Protect (via tight junctions) spermatids from immune system
Hormone production
Sertoli cells More info
Are in contact with each other
Tight junctions divide seminiferous epithelium into basal and adluminal compartments
Spermatogonia reside in basal compartment
Early spermatocytes pass through sertoli cell barrier into adluminal compartment (isolated from blood)
Immune system recognized spermatids as foreign
Sertoli cells hormone production
Release of androgen binding protein (ABP) in response to follicle stimulating hormone (FSH) -> increases testosterone concentration in seminiferous tubules
Synthesize anti-eulerian hormone (AMH-anti-peramesonephric duct) in embryo –> prevents formation of female genitalia
Release inhibin –> suppresses secretion of FSH (pituitary negative feedback on FSH)
Interstitial leydig cells
Occur in clusters between seminiferous tubule
Nucleus is small, round, dark, eccentric
Cytoplasm is very eosinophilic (due to SER and MT, few ribosomes) and often foamy due to presence of lipids
Secrete testosterone (also estrogens in board)
Controlled by ICSH= interstitial cell stimulating hormone (aka luteinizing hormone)
Testosterone
Produced by leydig cells
High concentrations are necessary to maintain spermatogenesis
Responsible for secondary male sex characteristics and for libido=sexual drive
Other androgenic effects: stimulates development and secretory activity of male accessory glands
It has anabolic effect: stimulates growth of skeletal muscles and bones
Spermatic pathway
Seminiferous tubules Straight tubules Rete testis Efferent ductules Epididymus (head, body, tail) Vas deferens Urethra
Intratesticular ducts
Intratesticular ducts consist of the straight tubules, rate testis and efferent ductules
Lined by epithelium that varies from squamous to cuboidal to columnar
Rete testis is like a sponge that all sperm empties into
Efferent ductules have a distinction undulating profile
Which of the following hormones is not secreted by sertoli cells
testosterone
Epididymus
One very long coiled tubule surrounded by connective tissue
Lined by pseudo stratified columnar epithelium with stereo cilia- function to increase absorption of fluid, not moving maturing sperm
Presence of smooth muscle cells in its wall which are abundant in the tail region
Main functions are fluid resorption and secretion of glycoproteins, proteins, glycolipids and lipids
Site of sperm maturation (head, body) and storage (in the tail of epididymis)
Which is not an accessory sex gland
epididymus
Ductus deferens
Lined by pseudo stratified columnar epithelium lined with sterocilia
Characterized by prominent muscular –> peristaltic contractions that propel spermatozoa
In ruminants and stallions, near the junction with the urethra, the ductus deferent forms a male accessory gland known as the ampulla
During fetal life the migration of the testes towards its final position starts from
near the kidney
Accessory sex glands
Vesicular glands (seminal vesicles) Ampullary glands Prostate glands Bulbourethral glands Nb. Ampulla of the vas deferent Function: add substances to semen to promote fertilization Lined by simple (cuboidal or columnar) or pseudo stratified epithelium Are tubuloaveolar
Seminal vessicles
Vesicular glands are not present in carnivores
Produce fructose- source of energy for the sperm cells
