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GGE > Embryos - Male Reproductive System > Flashcards

Embryos - Male Reproductive System Flashcards

1
Q

Lateral view of male reproductive system

A
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2
Q

What does the dartos muscle constitute

A

The subcutaneous muscle layer of the scrotum - continues internally to make up the scrotal septum (the wall dividing the scrotum into 2 compartments for the testes)

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3
Q

Where do the 2 cremaster muscles descend from

What do the dartos and cremaster muscles do together

A

descend from internal oblique muscle

2 cremaster muscles cover each testis like a muscular net

By contracting simultaneously, the dartos and cremaster muscles can elevate the testes in cold weather (or water), moving the testes closer to the body and decreasing the surface area of the scrotum to retain heat

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4
Q

What are the raphae

A

Raised medial thickening on the surface

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5
Q

Describe the outer tunica vaginalis of the scrotum

A

A serous membrane that has both a parietal and a thin visceral layer

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6
Q

What lies deep to the tunica vaginalis

A

Tunica albuginea - a tough, white dense CT layer covering the testis itself

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7
Q

Name the 2nd function of the tunica albuginea (other than covering the outside of the testis)

A

It also invaginates to form septa that divide the testis into 300-400 structures called lobules, and sperm develop in SEMINIFEROUS TUBULES within the lobules

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8
Q

When does the testes descend into the scrotal cavity

A

During the 7th month of the development period of a male foetus

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9
Q

What is cryptorchidism

A

When 1 or both of the testes fail to descend into the scrotum prior to birth

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10
Q

Sagittal view of the testis

A
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11
Q

Where does sperm travel to, after it has been produced at the seminiferous tubules

A

Transferred to epididymis to mature

Leave the epididymis during an ejaculation via the ductus deferens

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12
Q

What are seminiferous tubules composed of

A

Developing sperm cells surrounding a lumen, the hollow centre of the tubule, where formed sperm are released into the duct system of the testis

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13
Q

Where does sperm go once it leaves the lumen of the STs

A

From the lumen of the STs, sperm move into the straight tubules (tubuli recti) and from there into a fine meshwork of tubules - rete testes

Sperm leaves the rete testes and the testis itself through the 15-20 efferent ductules that cross the tunica albuginea

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14
Q

What do sustentacular cells do

A

Support the testis

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15
Q

Name the group of developing germ cells

A

Germ cells

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16
Q

How does the development of germ cells progress within the tubule

A

From the basement membrane (at the perimeter of the tubule) towards the lumen

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17
Q

Name the group of developing cells in the STs

A

Germ cells

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18
Q

What do sertoli cells do

Where are they found

A

These elongate, branching cells are sustentacular cells that secrete signaling molecules that promote sperm production and can control whether germ cells live or die

They are found in epithelial tissue, and extend physically around the germ cells from the peripheral basement membrane of the seminiferous tubules to the lumen

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19
Q

How is the blood-testis barrier created

What is its function

A
  • Tight junctions between these sustentacular cells create the blood–testis barrier
  • this keeps bloodborne substances from reaching the germ cells and, at the same time, keeps surface antigens on developing germ cells from escaping into the bloodstream and prompting an autoimmune response
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20
Q

What are the least mature cells called

A

Spermatogonia

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21
Q

Where are spermatogonia found

Can they differentiate

A

They line the basement membrane inside the tubule

Spermatogonia are the stem cells of the testis, which means that they are still able to differentiate into a variety of different cell types throughout adulthood

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22
Q

What is spermatogenesis

A

The process that begins with spermatogonia, which then divide to produce primary and secondary spermatocytes, then spermatids and concludes with sperm produced

(Occurs in STs)

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23
Q
A
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24
Q

How long does it take for a cycle of spermatogenesis to take place

A

64 days

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25
Q

How often does a new cycle of spermatogenesis start

A

Every 16 days but it can vary - not synchronous across the STs

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26
Q

Cross section of a ST

A
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27
Q

Overview of spermatogenesis

A
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28
Q

Describe the appearance of the haploid spermatid

A

Look similar to earlier stages of spermatogenesis - round shape, central nucleus and a large amount of cytoplasm

29
Q

Define spermiogenesis

A

Transforms these early spermatids, reducing the cytoplasm, and beginning the formation of the parts of a true sperm, and a spermatozoa is produced

30
Q

Structure of formed sperm

A

Smaller than most cells in the body

Verry little cytoplasm in the head

31
Q

How is the axial filament (central strand of flagellum) formed

A

From one centriole inside the maturing sperm cell during the final stages of spermatogenesis

32
Q

What is the role of the epididymis

How long does it take for sperm to move through it

A

Maturation of sperm occurs here

12 days

33
Q

How is sperm moved through the epididymis

A

Sperm enters the head of the epididymis and are moved along by the contraction of SM lining the epididymal tubes

34
Q

Where are mature sperm stored in the epididymis

A

Stored in the tail until ejaculation occurs and then pushed by SM contraction to the ductus deferens

35
Q

Where can the vas deferens be found

A

In the spermatic cord

36
Q

Where does the vas deferens extend to superiorly

A

Into the abdominal cavity through the inguinal canal, continues posteriorly to the pelvic cavity, ending posterior to the bladder where it dilates in a region called the ampulla

37
Q

How much of semen is made up of sperm

A

5%

38
Q

What accessory glands produce semen

A

Seminal vesicles

Prostate

Bulbourethral glands

39
Q

How much of the semen volume do seminal vesicles contribute

A

60%

40
Q

What does seminal vesicle fluid contain

A

Large amounts of fructose, which is used by the sperm mitochondria to generate ATP to allow movement through the female reproductive tract

41
Q

What structure of the ductus deferens is the seminal vesicle associated with

A

The ampulla

42
Q

Now containing seminal vesicle secretions, where does the fluid move to next

A

The associated ejaculatory duct - a structure formed from the ampulla of the ductus deferens and the duct of the seminal vesicle

43
Q

Where is the prostate gland located

A

Anterior to rectum at the base of the bladder surrounded by its prostatic urethra (the portion of the urethra that runs within the prostate)

44
Q

What sort of tissues is the prostate made from

A

Muscular and glandular tissues

45
Q

What does the prostate release

A

Excrete an alkaline, milky fluid to the passing seminal fluid (now called semen) that is critical to first coagulate and then decoagulate the semen following ejaculation

46
Q

How does the temporary thickening of semen help in fertilisation

A

Helps retain it within the female reproductive tract, providing time for sperm to utilise the fructose provided by seminal vesicle secretion

When the semen regains its fluid state, sperm can then pass farther into the female reproductive tract

47
Q

Change in size of the prostate over a lifetime

A

Normally doubles in size during puberty

At 25 it begins to enlarge again

48
Q

What is BPH - Benign Prostatic Hyperplasia

A

abnormal growth of the prostate

Causes constriction of the urethra as it passes through the middle of the prostate gland, leading to a number of lower UT symptoms

(40% of men have some degree @ 60)

49
Q

What do the bulbourethral glands release

What is its purpose

When is it released

A

A thick, salty fluid that lubricates the end of the urethra and vagina and helps to clean urine residues from the penile urethra

Fluid is released after the male becomes sexually aroused, and shortly before the release of semen => pre-ejaculate

50
Q

Cross Sectional view of the penis

A
51
Q

What is the end of the penis called

A

Glans penis and has a high conc of nerve endings, resulting in very sensitive skin that influences the likelihood of ejaculation

52
Q

What does the foreskin/prepuce contain

A

A dense conc of nerve endings, and both lubricate and protect the sensitive skin of the glans penis

53
Q

How does erection occur

A
54
Q

How does erection occur

A
  • Nitric oxide (NO) is released from nerve endings near blood vessels within the corpora cavernosa and spongiosum
  • Release of NO activates a signaling pathway that results in relaxation of the smooth muscles that surround the penile arteries, causing them to dilate
  • This dilation increases the amount of blood that can enter the penis and induces the endothelial cells in the penile arterial walls to also secrete NO and perpetuate the vasodilation
  • The rapid increase in blood volume fills the erectile chambers, and the increased pressure of the filled chambers compresses the thin- walled penile venules, preventing venous drainage of the penis
55
Q

What enzyme degrades a key component of the NO signalling pathway in the penis

A

PDE5

56
Q

What cells produce testosterone (steroid androgen hormone)

A

Leydig cells

57
Q

Where are leydig cells located

A

Between the STs in the testes (hence sometimes called interstitial cells)

58
Q

When is testosterone secreted in development

A

By the 7th week of development, with peak concentrations reached in the 2nd trimester

  • results in anatomical differentiation of the male sexual organs
59
Q

How much testosterone do leydig cells produce per day

A

6-7mg

60
Q

What does testicular steroidogenesis result in

A

Testosterone concentrations that are 100 times higher in the testes than in the circulation

Maintaining these normal concentrations of testosterone promotes spermatogenesis

61
Q

Other than the testes, where else is testosterone secreted

A

By the adrenal glands in both sexes

By the ovaries, although most is converted to estradiol

62
Q

Regulation of testosterone production

A
63
Q

Name the 3 parts of the male urethra

A

Prostatic - most dilatable, opening of ejaculatory duct

Membranous - urogenital diaphragm, sphincter urethrae, bulbourethral glands (fixed and narrow)

Penile/Spongy - longest, lacunae openings of urethral glands, commonly infected in venereal disease

64
Q

How much does each gland contribute to content of semen

A

Testes - 2%

Prostate - 30%

Seminal vesicles - 65%

Bulbourethral/urethral gland - 1%

65
Q

What do the secretions of the seminal vesicles contribute

A

Fructose

Prostaglandins

Fibrinogen

66
Q

What do the secretions of the prostate contain

A

Proteolytic enzymes

Prostatic acid phosphatase

Prostate-specific antigen

67
Q

Contents of secretions of bulbourethral glands

A

Secrete alkaline mucus with lubricating properties

68
Q

What is hypospadia

A

The urethra fails to completely close

69
Q

INNERVATION NOTES

A

GGE (33 decks)

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