L1 - Anatomy, Histology, and Development Flashcards
At what month of development do the testes begin to descend into the scrotum?
Via what do they descend?
7th month
via inguinal canal
The testes develop from what specific part of the posterior abdominal wall?
The gonadal/genital ridges (retroperitoneal structures)
What is cryptorchidism?
How often does it occur?
A failure of one or more testes to descend into the scrotum from the abdomen.
Occurs in 2-5% of newborn males
What is the correct term for a failure of one or more testes to descend into the scrotum?
Cryptorchidism (Occurs in 2-5% of newborn males)
Rete testis - network/plexus of tubules linking seminiferous tubules (via straight tubules) to efferent ductules
What is the approximate temperature in the testicles?
~32-35 degrees Celcius
What is the rete testis?
A plexus or network of tubules linking the seminiferous tubules to efferent ductules (carry sperm)
Describe the avascular component of the seminiferous tubules (4)
Describe the interstitial compartment of the seminiferous tubules
Leydig (interstitial) cells, make up what % of adult testis mass?
20%
What are the general functions of the epididymis? (5)
Sperm maturation
Decapacotation (killing off the mutants/when those balls be full)
Motility
Transport
Storage
Describe the macro appearance of the epididymis
3-4 cm long, comma-shaped, with a head, body, and tail
How long is the epididymis tubule?
5 m
What connects the seminiferous tubules to the efferent ductules in the head of the epididymis?
The rete testis
Spermatic cord
Ductus/vas deferens
Efferent duct
Rete testis
Ductus epididymis
Straight tubule
If the immature sperm are moving rapidly, how long does it take them to move through the epididymis and achieve maturation?
2-4 days
The poorly developed tail of the epididymis contains the _____, which is continuous with _______
Ductus epididymis, which is continuous with the ductus deferens
What is the general histology of the epididymis?
Pseudostratified columnar epithelium
Principal cells in the epididymis have what roles and features? (4)
Non-motile stereocilia (microvilli)
Absorb excess fluid
Phagocytose degenerating sperm
Secrete chemicals for sperm maturation
What are basal cells in regards to the epididymis?
Small, round, stem cells that can create principal cells
How are spermatozoa transported from the testis towards the ductus deferens?
Peristalsis (smooth muscle cells)
What is the main role of the epididymis tail?
Mainly for absorption, secretion, and modification of tubular fluid - the stuff the spermy bois are suspended in.
The ductus deferens passes through what larger structure to reach the ampulla?
The ol’ inguinal canal
What histological tissue type is the ductus deferens?
Pseudostratified columnar epithelium with stereocilia
Why does the ductus deferens have thick circular and longitudinal muscularis layers?
Sperm is transported by peristalsis during ‘rest’ and by muscle contraction during the ol’ ejaculation.
Ejaculatory duct
Formed by the union of the ampulla of the ductus deferens and by ducts from the seminal vesicles
What does the ejaculatory duct join?
The prostatic urethra
What type of histology does the ejaculatory duct have?
Pseudostratified columnar epithelium
State the various subclassifications of the urethra as it exits the urinary bladder and terminates in the penis. Also, include average lengths
Starts as urinary duct at the base of the bladder, embedded in prostate tissue
Prostatic urethra (2-3 cm)
Membranous urethra (1 cm)
Penile urethra (15-20 cm)
Total length: 18 - 23 cm
What type of epithelium does the urethra have and why?
Transitional epithelium - allows maximum extension, if you know what I mean
Where are the seminal vesicles located?
Posterior to the bladder, lateral to the ampulla of the ductus deferens
What type of epithelium do the seminal vesicles have?
Pseudostratified, non-ciliated, columnar epithelium
Why do the seminal vesicles have well-developed rER?
For protein synthesis and subsequent secretion
What % of semen volume is provided by the seminal vesicles?
60%
Describe the semen volume provided by the seminal vesicles and what its general properties are (7)
Whitish yellow, viscous fluid
Alkaline to neutralise vaginal acidity
Fructose and other simple sugars (for energy for the spermy bois)
Amino acids
Prostaglandins
Fibrinogen
Ascorbic acid
What is the bulbourethral gland?
What does it do?
Paired, pea-sized glands within the urogenital diaphragm.
Secretes thick, clear, alkaline mucus into the urethra to neutralise traces of acidic urine in the urethra.
Also has glycoproteins in mucus (pre-seminal fluid) for lubrication
Approximately how many prostatic ducts open into the urethra?
~20-30
What type of epithelium does the bulbourethral gland have?
Simple columnar epithelium
What is the specific name for the glands in the bulbourethral glands?
Tubuloalveolar glands
What type of epithelia does the prostate gland have?
Simple columnar/cuboidal/squamous/psuedostratified epithelia
What % of semen volume does the prostate gland contribute?
Describe its contribution
30%
Milky, alkaline fluid
What important contributions to semen composition does the prostate gland make? (4)
Clotting enzymes
Prostate acid phosphatase (PAP)
Prostate-specific antigen (PSA) - a diagnostic marker for prostate disease
Citric acid (also a diagnostic marker)
What are the 3 zones of the prostate?
- Peripheral zone
- Central zone
- Transitional zone
Describe the peripheral zone of the prostate gland (3)
70% of glandular tissue here
Most susceptible to prostate carcinoma and inflammation
Palpable during a rectal exam
Describe the central zone of the prostate (2)
25% of the glandular tissue of the prostate here
Resistant to disease
Describe the transitional zone of the prostate
Innermost zone surrounding the urethra
Site of prostate benign hyperplasia (PBH)
Nodular growth compresses urethra (dysurea)
Which zone of the prostate surrounds the urethra?
The innermost zone