Lecture 5: Male Reproduction Flashcards
What is the function of the testes?
Produces gametes (exocrine) (spermatozoa) and steroids (endocrine)
What is the function of the duct system?
Transport of gametes
What is the function of the accessory glands?
Produce additional additives to the semen
Additives
- fructose → seminal vesicles
- citric acid, fibrinolysin, PSA → prostate
Where does the production of sperm occur? Where does it travel after this?
Produced in the testis → carried externally through the duct system → exits through the penis
Testes (produce sperm) → epididymis (duct system) → vas deferens (duct system) → seminal vesicles (accessory gland) → prostate gland (accessory galnd) → urethra (penis)
What are the layers of the scrotum (4)?
- Skin
- Dartos muscle (from the membranous layer of superficial fascia)
- Colles’ fascia (CT)
- Parietal tunica vaginalis (from peritoneum)
Skin → dartos → colles fascia → parietal tunica vaginalis → visceral tunica vaginalis → tunica albuginea → testis
What are the layers of the testis (2)?
- visceral tunica vaginalis
- tunica albuginea
Skin → dartos → colles fascia → parietal tunica vaginalis → visceral tunica vaginalis → tunica albuginea → testis
Where is the testis located?
in the scrotum
Where are Leydig cells located within the testis? What is their function?
- within interstitial space of testis
- produce testosterone
Where does gametogenesis occur within the testis?
- Occurs within the seminiferous tubules
- Also contain supporting Sertoli cells
What structure divides the testis into lobules?
septum from the tunica albuginea
What two structures make up the tunica albuginea?
mediastinum + septum
Mediastinum → thickened area of posterior aspect of testis = vessels, nerves, and ducts enter and leave here
What are the 2 compartments of the testis? What does each contain?
- interstitial compartment → contain vasculature, lymphatics, and Leydig cells
- seminiferous tubule compartment → divided into basal and adluminal compartments by Sertoli - Sertoli cell tight junctions
Tubular wall → made of fibroblasts + CT
What compartment is the largest in the fetal testis? What does this compartment contain?
- interstitial comparment is the largest
- Leydig cells are indistinct and mostly nonfunctional
- Tubules contain supportive cells and gonocytes but lack a lumen
Gonocytes → pale staining precursors to the germ cells
Supportive cells → early Sertoli cells
What is the tunica vaginalis?
- layer of the scrotum
- thin layer of CT covered by mesothelium
What is the tunica albuginea?
- layer of the testis
- thick layer of CT which contains the functional parts of the testis
Which cells are the primary producers of testosterone? Where are they located?
- Leydig cells
- Interstistial space of testis
Has round nucleus often seen with a ring of heterochromatin
Cells that produce steroids are characterized by an abundance of certain organelles. These include which organelles (3)?
- Golgi → lipid transport
- sER → steroid hormone synthesis
- Mitochondria with tubular cristae
What is testosterone derived from? What stimulates its secretion?
- Derived from cholesterol
- Stimulated by the action of luteinizing hormone (LH) from the anterior pituitary
LH secreted by basophils
What are the functions (2) of inhibin (from Sertoli cells)?
- inhibits activation of LH release = prevents testosterone production
- inhibits FSH + LH in the anterior pituitary
- Negative feedback loop
What is the function of the androgen-binding protein (ABP)?
Binds testosterone to keep it in the tubules = ↑ testosterone
What 4 cells increase testosterone?
- LH
- FSH
- Leydig cells
- ABP (sertoli)
What separates the seminiferous tubule from the interstitium? What is it made up of?
- Separated by tubular wall → made up of CT layers → layers of fibroblasts and a distinct basement membrane
What are the supporting cells aka “nurse cells” of the seminiferous epithelium (simple columnar)?
Sertoli cells
Rests on the basement membrane and reaches to the luminal surface
One of the primary functions of the Sertoli cell is the formation of speciliazed junctions. What are the 2 most important?
- Sertoli-Sertoli junction → divides epithelium into a basal & adluminal compartment
- Sertoli-Spermatid junction → forms as the spermatid reaches the luminal edge
Sertoli-Sertoli junction → in basal compartment
Sertoli-Spermatid → in adluminal compartment
What are the functions of the Sertoli-Sertoli junction (2)?
- Excludes most substances from reaching the adluminal compartment forming a blood-testis barrier
- Important in protecting the developing germ cells
What are the functions of the blood testis barrier (2)?
Sertoli-Sertoli junction
- Protects the germ cells from autoimmune destruction
- Prevent nutritional components from reaching the later stages of the germ cells
What is the result of the blood-testis barrier being broken down?
Destruction of the germ cells and infertility → immune cells see sperm as non-self and attack the cells
What is the function of the antimullerian hormone?
Only in females
prevents development of the mullerian duct
What cell produces the androgen binding protein, antimullerian hormone, inhibin and transferrin?
Transferrin → transfers iron
Sertoli cell
Where does spermatogenesis begin? What is the result?
In the basal compartment with the mitotic division of dark A spermatogonia → results in the production of Type A pale and dark
Spermatogonia → Type A (diploid) → Type B (diploid) → 1° spermatocyte (diploid) → 2° spermatocyte (haploid) → spermatid (haploid) → sperm (haploid)
What does the Type B spermatogonia divide mitotically to form?
primary spermatocytes
After formation of primary spermatocytes, meiosis begins in the ______ compartment.
adluminal
What is the result of the first meiotic division in spermatogenesis?
Results in secondary spermatocytes and these divide in the second division to form spermatids
What do the early spermatids in spermiogenesis differentiate into?
elongated spermatids and the mature sperm (aka spermatozoa) in lumen
Why is the development of germ cells in spermatogenesis not synchronized throughout the tubule?
Allows for constant production of sperm
Different from females who are born with a set number of eggs
What is 1 important factor that can cause the degradation of the seminiferous epithelium?
increased temperature such as occurs in cryptorchidism
cryptorchidism = a condition in which one or both of the testes fail to descend from the abdomen into the scrotum
Explain the flow of sperm
seminiferous tubule → tubulus rectus → rete testis → ductuli efferentes → epididymis → vas deferens
What makes up the epithelium of the tubuli recti?
Sertoli cells → become more cuboidal as you move towards the rete testis
What cells (2) line the efferent duct?
Lined by nonciliated cuboidal cells and ciliated columnar cells
What type of epithelium lines the epididymis?
pseudostratified columnar epithelium with basal cells and principal cells
What are the functions of the epididymis (2)?
- absorbs a large proportion of the fluid to help concentrate sperm
- produces glycerophosphocholine → inhibits capacitation
What type of epithelium lines the vas deferens?
pseudostratified columnar epithelium (has stereocilia)
What type of muscle surrounds the vas deferens and how many layers are there?
Vas deferens is surrounded by smooth muscle organized into 3 layers
What happens when the vas deferens reach the prostate gland?
It expands into the ejaculatory duct which enters the prostate gland and empties into the prostatic urethra
Duct is line by simple columnar epithelium and lacks smooth muscle
What is the function of the pampiniform plexus of veins?
plays an important role in the counter-current exchange of heat → helps to keep the testis cooler than body temperature
What type of epithelium lines the navicular foss (terminal part of the urethra)?
stratified squamous
What are the mucous secreting glands (1) associated with the urethra?
mucous secreting glands of littre
The penile urethra begins as the urethra enters the penis. What structure surrounds this portion? What type of epithelium lines it?
- The portion is surrounded by the corpus sponiosum
- Lined with stratified and pseudostratified columnar epithelium
What makes up most of the penis?
erectile tissue organized as the corpora cavernosa and corpus spongiosum
Is an erection a sympathetic or parasympathetic response?
parasympathetic
What do the seminal vesicles secrete?
secrete fluid rich in fructose → an energy source for sperm
What type of epithelium lines the lumen of the seminal vesicle?
pseudostratified columnar epithelium
Same as vas deferens and epididymis
What type of tissue/muscle surrounds the tubule of the seminal vesicle?
surrounded by fibroelastic CT and by 2 layers of smooth muscle (inner circular and outer longitudinal)
What gland provides a large amount of the fluid of the semen?
prostate gland
What type of epithelium lines the prostate gland?
simple to pseudostratified columnar epithelium
What makes up the stroma of the prostate gland?
CT and smooth muscle
What are the primary secretory products of the prostate gland (3)?
- citric acid
- fibrinolysin
- prostate-specific antigen (PSA)
What is an indication of prostate cancer through a blood test?
increase in PSA
What glands does benign prostatic hypertrophy affect (BPH)? What is the result?
Affects the periurethral glands → results in restriction of the urethra
- Stroma shows an increase in the amount of smooth muscle
- Common in men over 65
Where does prostatic cancer originate?
originates in the peripheral gland (posterior lobe)
- Does not constrict the urethra (unlike BPH)
- Means that palpation of the gland through the rectum will often reveal the cancer → DRE = digital rectum exam
What cells are A? What cells are B?
Identify A, B, and C
Identify A, B, C, and D
Identify A, B, and C
Identify A, B, C, and D
Identify all the letters
- A & B= Sertoli cells
- C = Primary spermatocyte
- D = Spermatogonia
- E = Leydig cells
- F = Myoid cell
- G = Round spermatid
- During spermiogenesis, which phase takes place when the early spermatid starts to form the flagella and acrosomal cap?
a. Golgi
b. Acrosomal
c. Maturation
d. Elongation
a. Golgi
- Testosterone is secreted by ________ and stimulated by ________.
a. Sertoli cells; LH
b. Leydig cells; ABP
c. Sertoli cells; FSH
d. Leydig cells; LH
d. Leydig cells; LH
- Which product gets secreted by the seminal vesicles to serve as an energy source for spermatozoa?
a. Citric acid
b. Fructose
c. Glucose
d. Glycogen
b. Fructose
- The duct system is important for the transmittal of sperm, but which structure is also responsible for concentrating the sperm as it travels through the male reproductive system?
a. Vas deferens
b. Seminal vesicles
c. Epididymis
d. Seminiferous tubules
c. Epididymis
- Columnar epithelial cells which line the seminiferous tubules and support the germ cells are called:
a. Leydig cells
b. Sertoli cells
c. Spermatogonia
d. Myoid cells
b. Sertoli cells
- Sertoli cells produce androgen binding protein (ABP) in response to which other hormone?
a. FSH
b. LH
c. Testosterone
d. GnRH
a. FSH
- Which layer of the scrotum is derived from the membranous layer of the superficial fascia?
a. Colles’ fascia
b. Dartos muscle
c. Parietal tunica vaginalis
d. Tunica albuginea
b. Dartos muscle
- What is the secretory product of these cells?
a. Antimullerian hormone
b. Luteinizing hormone
c. Testosterone
d. Androgen
c. Testosterone
Identify the cell type:
a. Round spermatid
b. Primary spermatocyte
c. Spermatogonia
d. Secondary spermatocyte
a. Round spermatid
Identify the structure:
a. Corpus cavernosum
b. Penile urethra
c. Seminal vesicle
d. Prostate
a. Corpus cavernosum
- Which of the following best describes spermiogenesis?
a. Meiotic cell division
b. Formation of secondary spermatocytes
c. Cell differentiation of spermatogonia
d. Mitotic cell division
a. Meiotic cell division
- Identify the structure:
a. Pampiniform vein
b. Seminal vesicle
c. Corpus spongiosum
d. Vas deferens
d. Vas deferens
