7. Male Histo Flashcards
Testis are a paired organ that is surrounded by __________ in the the scrotum and suspended by a spermatic cord.
What then happens to the tissue that surrounds it?
Tunica albuginea.
The tunica albuginea will thicken posteriorly to form mediastinum testis, which contains the rete testis.
What surrounds the tunica albuginea?
2 layers of tunica vaginalis:
- Parietal tunica vaginalis, which lines the scrotum.
- Visceral tunica vaginalis, which lines the tunica albuginea.
Each.testis is divided into ~250 lobules.
What makes up a lobule?
- Seminiferous tubule
- Leydig cells
What is the organization of cells in the seminiferous tubules?
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Seminiferous tubules is a stratified epithelium made up of 2 populations of cells:
- Sertoli cells (support cells)
- Spermatogenic cells, which become mature sperm.
- that are surrounded by peritubular (myoid) cells which create a peristaltic wave to move spermatozoa through the tubule.
In the testis, seminiferous tubules become what?
- The end of the seminiferous tubules are located near the mediastinum. The ends become [straight tubules].
- Proximal ends have sertoli cells and distal ends have simple cuboidal cells.
- Straight tubules-> become rete testis, which is a anastomosing system in mediastinum.
What type of cells are rete testis?
- Simple cuboidal epithelium
- Low columnar epithleium
The epididymis lies along the superior and posterior surface of the testis and allows for sperm maturation, which takes 2-12 days.
What are the parts of the epididymis?
1. Head
2. Body
3. Tail
What is the head of the epididymis?
- Contains efferent ductules (pseudostratified columnar epithelium), which connect the rete testis to the head of the epididymis.
What is the body of the epididymis?
- Body contains the duct of the epididymis, which is made up of principal cells (pseudostratified columbar epithelium with steriocilia)
What is the tail of the epididymis?
Connects the duct of epididymis -> ductus deferens.
What kind of muscle surrounds the epididymis?
Smooth muscle that assists with peristalsis.
What is the ductus deferens?
Tube surrounded by loose CT, adipocytes and [pseudostratified columnar epithelium w/ stereocilia] and has a muscular wall made up of 3 muscular layers: inner and outer longitudinal layer and middle circular layer.
What is the ampulla?
- Ampulla is a dilated part of the vas deferens that leads to the prostate.
- The end will receive the duct of the seminmal vesicle, which helps to form the ejaculatory dict.
Histologically, what is different between the epididymis and vas deferens?
Lumen is folded, not smooth.
What are spermatogenic cells and how are they organized?
- Spermatogenic cells come from primordial germ cells in the yolk sac and mature into sperm.
- They are organized in layers at different stages of development BETWEEN sertoli cells inside of the seminiferous vesicles.
What is the spermatogonial phase?
- Sperm stem cells divide and become: type A spermatogonia or type B spermatogoia
- Type A: oval nuclei with basophilic, granular chromatin. They. can stay stem cells or become type B
- Type B: spherical nuclei with clumps of condensed chromatin around nucleolus. They will enter meiosis to become mature sperm.
What process occurs in spermatocyte phase?
- Spermatocyte phase -> meiosis.
- 1. Type B spermatogonia -> primary spermatocytes (2N, 4D) via mitotic division.
- Primary spermatocytes. -> secondary spermatocytes (1N, 2D)
- Secondary spermatocytes -> spermatids (1N, 1D)
What is the spermatid phase?
Spermiogenesis: spermatids become mature sperm cells. Occurs in 4 phases:
- Golgi phase
- Cap phase
- Acrosome phase
- Maturation phase
Describe what occurs in the first two phases of spermiogenesis.
- Golgi phase:
- Acrosome vesicle forms next to the nucleus. Where it forms will determine the anterior pole of the sperm.
- Centrioles move to posterior pole and begin to form axoneme of the tail of the sperm.
- Cap phase:
* Acrosome enlarges and creates a acrosome cap. Nuclear envelope will attach.
Describe what occurs in the last two phases of spermiogenesis.
- Acrosome phase: the spermatid will orient itself so that the head is embedded in the sertoli cell and points toward the basal lamina. Manchette forms from cytoplasmic microtubules.
- Maturation phase: Extra cytoplasm is removed as residual bodies, creating mature spermatozoon. The spermatids are then released from sertoli cells -> lumen of the seminiferous tubules.
What is the structure of a mature sperm?
Mature sperm is separated into a head and tail.
- Head has a flat, elongated nucleus and is covered by acrosomal cap that has hydrolytic enzymes.
Tail has three pieces:
- Middle -has the mT
- Principal- fibrous sheath that adds stability
- End- contains the axonemal complex that connects microtubules.
What is the pathway of sperm?
- Semniferous tubules -> straight tubules (tubulus rectus) -> rete testis -> efferent ductule -> epididymal duct (body and tail) -> vas deferens -> ejaculatory duct -> urethra
What are sertoli cells (aka support cells)?
Shape?
- Sertoli cells are support cells give structural support to seminiferous tubules. and developing spermatozoa.
- They also secrete ABP, which binds T and DHT with high affinity.
- Columnar with apical and lateral processes that surround spermatogenic cells.
How. are sertoli cells organized?
Sertoli cells are bound together, creating a sertoli cell- sertoli cell junctional complex. This creates a tight junction called the blood testes barrier that makes a basal epithelial compartment. and luminal compartment
what makes up the tunica/lamina propria of sertoli cells?
Layers of myoid cells that contract to create peristaltic waves to help move spermatozoa and testicular fluid from tubules -> ducts.
What happens to the tunica/lamina propria of sertoli cells as we age?
- Thickens -> decreasing rate of sperm production and reduces size of seminiferous tubules.
- If this occurs early -> infertility.
What are Leydig cells (interstitial cells)?
- Shape?
- 2 big characteristics?
- Functions?
- Shape: Leydig cells are large, polygonal, eosinophillic cells
- Characteristics: fat droplets and crystals of reinke (rod shaped cytoplasmic crystals of androgenic hormones)
- Functions:
- Has a extensive sER to make testosterone (95%) and insulin-like protein 3 (INSL3)
What is the function of T and INSL3 during embryo, puberty. and adulthood?
Embryo:
- T is needed to develop gonads
- INSL3 causes testes to descend
Puberty:
- T is needed to make sperm, cause secretions from accessory sex glands and secondary sex characteristics
- INSL3 causes meiotic division in seminiferous tubules
Adult:
- T is needed to maintain sperm, secondary sex characteristics, cause accessory sex glands to secrete oxytocin
What are our accessory sex glands?
- 1. Seminal vesicles (2)
- 2. Bulbourethral glands (2)
- 3. Prostate (1)
What are the seminal vesicles?
Paired tubular glands on the posterior wall of the bladder, next to the ampulla of the ductus deferens. Duct of seminal gland joins with the ampulla of the DD to make the EJACULATORY DUCT :)
What. are the layers. of the seminal vesicles?
3 layers
- Mucosa: folded to increase secretory SA.
- Smooth muscle: contracts when we ejaculate to move secretions -> ejaculatory. duct
- Fibrous coat
What kind of epithelium do seminal vesicles have?
Pseudostratified columnar epithelium (non-cilated)
What do seminal vesicles secete?
Alkaline whitish, yellow fluid (w fructose, AA, ascorbic acid and prostaglandins) that nourishes sperm and that makes up 75% of semen.
What are bulbourethral glands?
Paired, pea size glands in the urogenital diaphragm.
Secretes pre-cum (clear-mucus like with galactose, sialic acid and methylpentose) that will lubricate spongy urethra. and neutralize acidic urine.
What kind of epithelium do bulbourethral glands have?
simple columnar epithelium
Prostate is the largest accessory gland and is the size of a walnut.
What kind of epithlium does it. have?
Simple columnar or pseudostratified
What does the prostate gland do?
- Secretes clear, akaline fluid to neutralize the acidic environment of Vag.
- Provides nutriens, transports and liquifies sperm.
What are the 4 zones of the prostate?
1. Peripheral
2. Transitional
3. Central
4. Periurethral
Describe the peripheral and transitional zone of prostate gland.
- Peripheral zone is the posterior and lateral part that is palpable during DRE. Prostatic carcinomas are located. here.
- Transitional zone surrounds prostatic urethra. During BPH, nodules compress prostatic urethra.
Describe the central and periurethral zone of prostate gland.
- Central zone: surrounds ejaculatory duct. Basophilic cytoplasm with large nuclei.
- Periurethral- has mucosal and submucosal components that get big in late stages of BPH, causing worsening of sxs.
What problem primarily occurs in the transitional zone?
- Benign prostatic hyperplasia (BPH), which will develop into periurethral zone later.
- Nodular masses form that obstruct prostatic urethra.
- 50%. of men with BPH will have symptoms and by 80 yo, 90% of men will haveit.
What problem typically occurs in peripheral zone of prostate?
- Prostate adenocarcinoma that are easily felt on DRA.
- Progress is tracked using PSA (prostate specific antigens)
Sx of prostate cancer
- need to pee alot
- dysuria
- hematuria
- low back pain
SEMEN
Secretions from:
pH:
Secretions from: testes, epididymis, ductus deferens, prostate, seminal vesicles, bulbourethral glands
pH= 7.7 to neutralize urethra and vagina.
Transport of sperm
SEVEN UP
Seminiferous tubules -> epidymis -> vas deferencs -> ejaculatory duct -> nothing -> urethra -> penis
What makes up penis?
- 3 corpora bound tuogether by tunica albuginea
- 2 dorsal masses (L/R corpora cavernosum)
- 1 ventral mass (corpus spongiosum, which surrounds spongy urethra
What is the erectile tissue?
irregular, interconnected vascular sinuses with fibrocollagenous stroma.
What runs in the R/L corpora cavernosa?
Deep a. of penis, which branches into helicine arteries.
What happens when sinuses of deep a. of penis in R/L corpora cavernosa fill with blood? and how does blood drain?
- Blood fills sinuses -> increases in size and rigity -> compresses venous outflow -> traps blood in sinus -> maintains erection.
- Drain: Sinus anastomoses with veins to drain blood
Describe process of erection
- PNS signals from pelvic splanchnic nerves go to penis
- NO is released
- GC: GTP -> cGMP
- cGMP -> + Ca2+ storage in smooth muscle cells -> smooth muscle relaxes
- increases blood floow into sinusoids of erectile tissue
- compresses veins (tunica albuginea cannot be compressed)
- Erection
What is detumescence?
Termination of erection via SNS
What is the process of detumescence?
- SNS causes contraction of SM and dexcreased blood flow to sinusoids -> opens veins of penis and releases blood
- PDE breaks down cGMP -> decreased smooth muscle relaxation.
Viagra (PDE inhibitors) do what?
increase cGMP -> increase blood flow into sinusoids.
