TOB Male Repro System (19)

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TOB Male Repro System (19)
2013-11-07 20:10:14
Tissue Organ Biology

Exam 4
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  1. Testes
    • are paired, located in the scrotum, & have both exocrine (sperm) + endocrine (sex hormones) functions
    • develop in the fetus under the control of testicular determining factor (TDF), a transcription factor from the sex-determining region of the Y chromosome (SRY)
    • testis develop in the posterior abdominal wall; are sent into scrotum & drag with it a bubble like structure called the tunica vaginalis, an extensions of the peritoneum
  2. Layer of the Testis
    • tunica vaginalis: outermost double-layered (extensions of the peritoneum)
    • tunica albuginea: inside the vaginalis, a dense fibrous CT capsule that thickens along the posterior surface to form the mediastinum testis
    • tunica vasculosa: underneath the albuginea, a loose CT layer containing blood vessels and lymphatics that invaginates into septa, dividing testes into compartments (lobules)
    • inside each lobule are 1-4 seminiferous tubules + interstitial tissue between the tubules

    • section of a testicle
    • tunica vasculosa septa divide internal area into lobules
    • in lobules are highly coiled seminiferous tubules
    • cross-section of seminiferous tubule
    • interstitial tissue surrounding seminiferous tubule is where blood vessel, lyphatics, & *Leydig Cells, which make testosterone, are located
    • sperm are made in the seminiferous tubules
  3. Leydig (Interstitial) Cells
    • secret testosterone, DHEA (dehydroepiandrosterone), & 5-alpha-androstenedione, a process controlled by LH & interstitial cell stimulating hormone (ICSH)
    • contain extensive SER, lipid droplets, lots of mitochondria, & a well-developed Golgi apparatus
    • found in space between seminiferous tubules, along w/ CT, nerves, blood, & lymphatic vessels
    • are derived from embryonic genital ridge mesoderm
    • can see proteinaceous crystals of Reinke in the cytoplasm
  4. Sertoli Cells (Supporting)
    • large cells that sit on basal lamina & their cytoplasm reaches all the way to the seminiferous tube lumen
    • they physically support the developing sperm, provide them with nutrients, & move them toward the lumen
    • controlled by FSH from the pituitary
    • they protect sperm by forming the blood-testis barrier which protects the spermatogenic cells from autoimmune attack
    • have lots of microvili; can change their shape
    • are derived from mesoderm
    • they phagocytose residual bodies shed by maturing spermatozoa
  5. What are some factors the sertoli cells secrete?
    • Androgen binding protein (to maintain high levels of testosterone for the proper development of sperm)
    • mullerian inhibitory factor (inhibits becoming a female)
    • activin (stimulates FSH secretion)
    • inhibin (acts on pituitary to decrease FSH secretion)
    • K+ & HCO3-
  6. Spermatogonia
    • large, oval or round stem cells derived from primordial germ cells that are found on the basal lamina of seminiferous tubules
    • are diploid (2N chromosomes, 2N DNA)
    • when they divide they produce more stem cells + a terminally differentiated primary spermatocyte
  7. What are the only spermatogenic cell type present before puberty?
    Spermatogonia: small, round cells with oval to round nuclei that sit on the basal lamina
  8. Primary Spermatocyte
    • are the 2nd layer of cells up from the basal lamina
    • are large cells with a large nucleus that contains dark worm-like strands of heterochromatins
    • these cells are in PROPHASE OF MEIOSIS I (1st meiotic division)
    • when they divide to make 2ndary spermatocytes cross-over of chromosomes can occur to produce daughter cells which are genetically DIFFERENT from the somatic cells (& susceptible to immunological attack)
  9. Secondary Spermatocyte
    • are the 3rd layer of cells up from the basal lamina
    • they complete the 2nd meiotic division to produce spermatids
    • will not have to identify histologically*
  10. Spermatids
    • are located next to the lumen
    • Early: small round cells with heterochromatic nuclei (jelly-filled donut)

    • Late: condensed nuclei, tapered cell body, & have a flagellum
  11. Spermiogenesis
    • process of cytodifferentiation w/ extensive rearrangement of the cellular components but NO cell division is involved. Includes:
    • Acrosome formation: caps the nucleus opposite to where the tail develops
    • Centriole migration
    • Flagellum formation
    • Mitochondria migration: around the flagellum to provide energy for movement
    • Condensation of nuclear chromatin
    • Sloughing off residual bodies
  12. maturation phase of spermiogenesis
    • Centriole migration: both move to the spermatid’s posterior pole; 1 forms flagellum, other a collar around flagellum
    • Flagellum formation
    • Mitochondria migration
    • Condensation of nuclear chromatin
    • Sloughing off residual bodies: excess cytoplasm
    • (everything but acrosome formation)
  13. acrosome
    • a specialized lysosome that contains hyaluronidase, neuraminidase, acid phosphatase, trypsin-like protease, & other PAS-positive carbohydrate-rich components
    • it's enzymes help to penetrate the cells of the corona radiata & zona pellucida of the ovum during fertilization
  14. Spermatozoa (Sperm)
    • are released into the lumen and move into the ducts
    • are haploid & have long flagella
    • are the end product of spermiogenesis
    • made up of a head (nucleus w/ anterior 2/3s covered by acrosome) & tail
  15. Spermatozoa Tail
    • neck: has proximal centriole + base of flagellum
    • middle piece: mitochondria arranged in a spiral around the flagellum with a classical 9+2 arrangement of microtubules (axoneme)
    • principal piece: longest, 7 outer fibers + axoneme
    • end piece: no fibrous sheath & ends with 18 single microtubules
  16. clonal nature of sperm development
    • the fact that during division from spermatogenia to spermatids cells' nuclei divide completely however they remain attached to each other by small cytoplasmic bridges
    • these bridges don't break until the sperms are released into the lumen, helping to synchronize the release of a LARGE number of mature sperms at the same time rather than just 1 by 1
  17. Blood-Testis Barrier
    • protects the developing sperms from autoimmune attack
    • is made up of a belt of junctional complexes joining Sertoli cells at their lateral aspects & separates seminiferous tubule into two compartments: the basal & adluminal compartment
  18. basal compartment
    • contains the spermatogonia and preleptotene spermatocyte
    • IS ACCESSIBLE to any blood-borne substances that can get through the basal lamina
  19. adluminal compartment
    • reaches from the junctional complex to the lumen & houses primary and secondary spermatocyte & spermatids
    • it is IN ACCESSIBLE to blood-born substances except those that are taken up by the Sertoli cells and passed through gap junctions to the spermatogenic cells
    • In this compartment are primary spermatocytes onward
  20. hormone control
    • hypothalamic gonadotropin-releasing hormone (GnRH) mediates the episodic release of the gonadotrophins (LH and FSH) from the anterior pituitary
    • LH --> Leydig cells: testosterone; feeds back negatively on GnRH & gonadotrophins production
    • FSH --> Sertoli cells: ABP + tubule fluid
  21. Dihydrotestosterone (DHT)
    • a more potent androgen made from testosterone by 5 α-reductase
    • the form of a sex hormone used by accessory and external sex glands such as the prostate gland
    • 5 α-reductase can be targeted to inhibit DHT under certain circumstances, such as prostate cancer
  22. Where is testosterone aromatized by aromatase to produce estradiol (an estrogen)?
    in the peripheral tissues, eg. hypothalamus & adipose tissue to help accentuate the feedback mechanisms
  23. Prolactin in the male reproductive system
    potentiates the effects of LH on Leydig cells & may also play a paracrine role in cell proliferation & differentiation in the male reproductive tissues (eg. prostate)
  24. Cryptorchism
    • condition in which one or both testes failed to descend into the scrotal sacs
    • sperms will not develop properly in the test is subjected to higher temperature
    • fertility rate in unilateral cryptorchism is about 50%, but fertility rate in uncorrected bilateral cryptorchism is nearly zero
    • it increases the risk of testicular cancer in the undescended testis
  25. Efferentes Ducts
    • where sperm is released after being made in the seminiferous tubules
    • are derivatives of the Wolffian ducts
    • a system of channels - first through the CT of the tunica albuginea then through the rete testis - conduct the sperms out of the testis and into the excurrent ducts:
    • Ductus epididymis
    • Ductus (Vas) deferens
    • Efferentes Ducts
    • note the wavyness of tissue surrounding the lumen - can be used to differentiate excurrent duct from seminiferous tubules; also have stacking of cells
    • some cells are ciliated to move the sperm along the tubule b/c they can't swim yet
    • in the center (lumen) of a cross-section of an excurrent duct you see sperm heads & residual bodies
  26. Ductus Epididymis
    • a single, highly coiled, long tube that can be divided into the head (caput), body (corpus) & tail (cauda) - where sperm enter from the efferentes ducts
    • an important site for sperm, transport, storage, protection, & maturation whose cells are also involved in phagocytosis of residual bodies
    • sperm are moved slowly forward by peristaltic contractions of the muscles
    • Ductus Epididymis
    • has pseudostratified epithelium with tall columnar cells
    • basal reserve cells are present
    • can see surrounding walls made of smooth muscle which gradually thickens along the length of the tube
    • can see sperm in cross sections of the lumen
  27. What is the purpose of the stereocilia on epididymus cells?
    • the epididymus' pseudostratified epithelium with tall columnar cells have apical (facing the lumen) stereocilia
    • these are long NON-motile microvilli that absorb extra fluid mixed in with sperm, concentrating the sperm and beginning their maturation process
  28. What does the epithelium of the ductus epididymis secrete?
    • factors such as citrate, fructose, vitamin C to nourish the sperm as well as:
    • 1. sialic acid
    • 2. glycerophosphoryl choline
    • 3. forward motility protein - allows sperm to SWIM straight by the end of the epididymis
    • the proper function of the epididymis depends on testosterone and there is a high concentration of androgen binding protein in the epididymis
  29. How long does it take for sperms to move through the epididymis?
    • about 12 days - they are stored there
    • by the time they move into the next structure, they have acquired nearly (but not all) the features necessary to fertilize an egg
  30. Ductus (Vas) deferens
    • a single straight tube with thick muscular walls the epididymis empties into and its other end opens into the ejaculatory duct
    • it runs in the spermatic cord between the testis and the inguinal canal then proceeds by itself toward the seminal vesicle & prostate
    • it contracts strongly during ejaculation
    • this is what's snipped to make men infertile
    • Ductus deferens
    • has a narrow lumen with mucosal folds
    • its lining is pseudostratified columnar epithelium with FEWER stereocilia than in the epididymis (most absorption has already taken place)
    • basal reserve cells are present
    • its wall contains 3 layers of smooth muscles (inner longitudinal, middle circular, outer longitudinal)
  31. What is present in the spermatic cord between the testis and the inguinal canal?
    • 1. ductus deferens
    • 2. blood vessels (eg. testicular arteries & pampiniform plexus)
    • 3. skeletal muscle (cremaster muscle - derived from abdominal wall muscle)
    • 4. testicular artery
  32. Where is the thickest muscular wall found in the In the male genital tract?
    • deferent duct (ductus deferens)
    • it has 3 layers of smooth muscle in its wall to propel sperm toward accessory glands where secretions are added resulting in semen
  33. Pampiniform Plexus of Veins
    • complex of veins that return from the testes which also function to regulate their temperature
    • arteriole blood traveling to the testis is warm, so the pampiniform plexus acts as a heat exchanger absorbing heat from blood in adjacent arteries, cooling the blood
    • an abnormal enlargement of the pampiniform plexus is called varicocele

  34. Accessory Sex Glands
    • contribute secretions to a large portion of the semen & help to stabilize, nourish, & propel sperm
    • they depend on dihydrotestosterone (DHT) for proper function
  35. Seminal Vesicles
    • paired structures each made up of a highly coiled 15cm long tube
    • the mucosa is highly folded with complicated BRANCHING
    • epithelial cells contain lots of secretory granules + yellowish lipid droplets
    • its secretions make up a large portion of the semen & are rich in fructose, inositol, ascorbic acid, fibrinogen, prostaglandins & several proteins
    • under the lamina propria are smooth muscles which contract during ejaculation
    • it opens into the ejaculatory duct
    • *sperm is NOT stored here (stored in epididymus)
    • mucosa foldings look like 'brain coral'
    • can see smooth muscle surrounding layer
    • pseudostratified epithelium
    • can see lipid droplets in epithelium under high magnification - show up in puberty
  36. Prostate Gland
    • seminal vesicles open into the prostate
    • parenchyma (functional part) consists of 3-50 compound tubuloalveolar glands w/ the ducts emptying independently into the urethra (which is continuous with the bladder): secretory/prostetic acini
    • the pseudostratified columnar epithelium contains secretory & basal cells
    • the epithelium produces prostatic fluid, rich in citric acid & acid phosphatase, tissue plasminogen activator, lactoferrin, amylase, fibrinolysin, & lipids
    • its stroma is fibromuscular: contains smooth muscle cells + CT [can stain for smooth mus. actin]
  37. Prostate Parenchyma Zones
    • (from outside to inside)
    • peripheral: where carcinoma (prostate cancer) usually develops
    • central
    • transitional: where BPH usually develops
    • periurethral
  38. Carcinoma of the Prostate
    • cancer that usually arises in the PERIPHERAL zone of the prostate, classically in a posterior location, thus palpable on rectal exam
    • most common form of cancer in men and the 2nd leading cause of cancer death
    • is usually found in men above 50 years of age
    • In the normal prostate, basal cells form a complete ring around secretory cells; they're ABSENT in cancerous tissues
  39. Benign prostatic hyperplasia (BPH)
    • an increase in both the parenchymal and stromal components of the prostate; results in trouble urinating
    • usually arises in the TRANSITIONAL zone of men above 50 years of age (is very common in)
    • hyperplastic nodules later develop in the periurethral zone & may encroach upon the urethra & affect urination
  40. Prostatic acid phosphatase (PAP)
    a tissue specific marker
  41. Prostate specific antigen (PSA)
    • a proteolytic enzyme that helps to liquefy the semen which coagulates after ejaculation
    • high levels can be used to identify a potential carcinoma/cancer
  42. What is the largest of the male accessory sex glands?
    the prostate
  43. Bulbourethral Gland (Cowper)
    • paired, small tubuloalveolar accessory sex glands lined by CUBOIDAL epithelium
    • they secret a clear sialoprotein-rich mucus into the membranes urethra (the portion of the urethra which runs through the urogenital diaphragm) during sexual excitation
    • the secretion lubricates for the urethra before ejaculation
    • Bulbourethral Gland
    • mucus secreting cells
    • basally located nucleus
    • pale cytoplasm
  44. Penis
    • is made up of three cylinders of erectile tissues
    • corpora cavernosa: two side-by-side ones
    • corpus spongiosum: single (bottom) one; holds the urethra
    • white = tunica albuginea CT
  45. Erectile tissue
    • an irregular network of fibrous connective tissue trabeculae containing smooth muscles
    • the trabeculae form a framework for interconnecting channels lined by endothelium (lacunae, vascular sinuses)
  46. Corpora cavernosa
    • two dorsal erectile cylinders w/ vascular sinuses enclosed by a thick, dense connective tissue called the tunica albuginea
    • a deep artery runs through the center of each cylinder
  47. Corpus spongiosum
    • a single cylinder of erectile tissue surrounded by a thin layer of connective tissue, the tunica albuginea
    • the penile urethra runs through the center of the cylinder
    • the proximal end of the cylinder is larger than the shaft and forms the bulb of the penis
    • the distal end of the cylinder is larger and forms the glands penis
  48. Flaccid Penis
    • peripheral dorsal arteries in the CT supply much of the arterial blood which is drained by the superficial veins
    • arteriovenous shunts between the deep arteries in the corpora cavernosa & the superficial veins are OPEN
    • deep artery branches feeding the vascular spaces (the helicine arteries) are CLOSED
    • with no blood flowing in, vascular lacunae are empty
  49. Erect Penis
    • during erection the arteriovenous shunts SHUT DOWN
    • blood from the deep helicine arteries flows into the vascular sinuses (lacunae)
    • the veins which drain the sinuses are located at the periphery, close to the CT sheath (tunica albuginea)
    • compression of the veins against the tunica albuginea slows the exit of the blood
    • erection is maintained when more blood fills up the lacunae and stays there more than blood leaving via veins
  50. Detumescence
    when the penis loses its rigidity as a result of the arteriovenous shunt opening up, the helicine arteries closing up, & blood draining out of the vascular lacunae
  51. Which type of nerves cause erection and which type causes ejaculation?
    • parasympathetic stimulation causes erection (closing the arteriovenous shunts, opening the helicine arteries, & relaxing smooth muscles in the trabeculae)
    • sympathetic stimulation causes ejaculation (contraction of the helicine arteries & return to the flaccid state)
  52. What role does nitric oxide play in erection?
    • a critical one
    • it's released by nerves in erectile tissues during sexual stimulation causes the production of cGMP which relaxes smooth muscle
    • this lets blood flow into the vascular lacunae 8--D erection
    • no NO means a flaccid penis when the release of NO has stopped,
  53. How does viagra work?
    • it inhibits PDE5 (phosphodiesterase type 5), which breaks down cGMP (responsible for relaxes smooth muscle relaxation letting blood flow into the vascular lacunae)
    • always blood flow!
  54. Penile urethra
    • urethra that runs through the penis
    • has a stratified cuboidal epithelium (that can changes into stratified squamous when inflamed, possibly cancerous)
    • small Littre glands that contain mucus secretory cells can be found in the periurethral tissue or in the epithelium (intraepithelial)
    • the mucus secretion helps to lubricate the urethra solely to move URINE out of the urethra (not sperm)
  55. Semen
    • a composite fluid with contributions from various sources (testis + accessory sex glands)
    • sperms must undergo capacitation before they can fertilize an ovum - it's last step of sperm maturation; it happens IN the female reproductive tract
  56. capacitation
    • freshly ejaculated sperm are unable to fertilize until they undergo capacitation, a process where the glycoprotein coat and seminal proteins are removed from the acrosome surface (takes about 7 hours)
    • in vivo this step typically occurs in the female reproductive tract after ejaculation
  57. primary spermatocytes
    (4N; 92; tetraploid) formed from spermatogonial stem cells dividing by mitosis; are initially diploid and are undergo meiosis
  58. secondary spermatocytes
    (2N; 46; diploid) primary spermatocytes that have undergone meosis I; they undergo a meiosis II which results it HAPLOID spermatids
  59. one primary spermatocyte produces:
    four spermatids
  60. spermiogenesis
    • the process by which spermatids are remodeled to form mature sperm (spermatozoa)
    • elongation, tail development, cytoplasm shed