Physiology-Male Reproductive System

Question 1

Identify the different structures labeled below:

Answer 1

1) Tunica albuginea (connective tissue capsule) 2) Septae (invaginations of tunica albigunia separating lobules) 3) Seminiferous tubules 4) Visceral layer of tunica vaginalis 5) Parietal layer of tunica vaginalis 6) Mediastinum testes (where all vessels come in and go out)

Question 2

Identify the different structures labeled below

Answer 2

*

Question 3

What is the exocrine secretory product of the testes?

Answer 3

Spermatozoa from the seminiferous tubules

Question 4

What is the endocrine secretory product of the testes?

Answer 4

Testosterone from the Leydig cells in the testicular interstitium

Question 5

What composes the majority of the space in the testis?

Answer 5

Seminiferous tubules

Question 6

What are the spiral hairs in the center of the seminiferous tubules?

Answer 6

Flagellae of the developing spermatids, their heads are still in the seminiferous tubules.

Question 7

What cells are indicated in this slice from a testicle?

Answer 7

Yellow = tunica propria (CT covering each seminiferous tubule). Blue = fibroblasts, rarely peritubular contractile cells.

Question 8

What cells are responsible for forming the three dimensional network on top of the lamina propria in the seminiferous tubules?

Answer 8

Sertoli cells. They are tall, columnar cells that cover the thickness of the wall (lamina propria to the lumen)

Question 9

Why are Sertoli cells also called nursing cells?

Answer 9

Developing spermatids sit on their surface and utilize their nutrients and give them their waste. They also phagocytose failing cells.

Question 10

What forms the blood-testis barrier?

Answer 10

Sertoli-Sertoli junctional complex

Question 11

How can a vasectomy cause an immune reaction?

Answer 11

It breaks the blood-testis barrier.

Question 12

What products are secreted from the Sertoli cells?

Answer 12

Androgen binding protein (keeps androgen in the tubules) and inhibin (feedback inhibitor of FSH release in the pituitary gland).

Question 13

What is the sequence of events in spermato and spermiogenesis?

Answer 13

Spermatogonia (progenitor cells at base of seminiferous tubules) -> Primary spermatocytes (4n chromosomes & 2x DNA content from meiosis I) -> Secondary spermatocyte (1n chromosomes and 1x DNA, short lived) -> Spermatids (haploid in DNA and chromosomes) -> Spermatozoa (not yet motile/functional). As this process continues, the cells move closer and closer to the lumen.

Question 14

What are the two phases of spermatogenesis?

Answer 14

Proliferation: 1) maintain progenitor cell population via mitotic division 2) Reduce DNA content & chromosome number by 1/2 through meiotic division. Differentiation: morphological changes

Question 15

On EM what reflects the stage of sperm differentiation?

Answer 15

Their location in the wall: Green arrow = spermatogonia w/large nucleus. Orange arrow = primary spermatocytes actively dividing Yellow arrow = spermatids w/elongated nuclei.

Question 16

Why are secondary spermatocytes hard to find?

Answer 16

In meiosis II you do not replicate the DNA so it is an extremely fast process.

Question 17

What is spermiogenesis?

Answer 17

Spermatids begin to polarize from a round cell -> golgi accumulation fuses to form acrosomal vesical -> cell becomes more elongated -> acrosomal cap moves on top of nucleus -> flagella begins to develop -> mitochondria arranges around flagella -> cytoplasm is shed to leave nucleus, acrosomal cap and flagella. Spermatozoa leaving the seminiferous tubules are immotile and immature. Maturation takes place in the epididymis.

Question 18

What is in the head of a spermatozoa?

Answer 18

The acrosomal cap contains enzymes (hyaluronidase, acrosin) and DNA.

Question 19

What happens here?

Answer 19

Note the pseudostratified epithelium characteristic of the epididymis. This is where the spermatozoa mature and contains a lot of nutrients for the developing sperm.

Question 20

How does activation of the sperm occur?

Answer 20

Acrosomal contact with the egg.

Question 21

Where is the majority of blood supply found in the testis?

Answer 21

Intertitium. This is where the Leydig cells are that are secreting hormones into the blood. It will not be in the seminiferous tubules due to the testis-blood barrier produced by the Sertoli cells.

Question 22

Run through the development of the testis?

Answer 22

Week 3) Yolk sac -> genital ridge. Week 4-8) Primordial testis, hCG stimulates Leydig production of testosterone Week 9) Scrotum forms, testis move to internal inguinal ring Week 13) Processus vaginalis forms path for testis decent into scrotum Weeks 26-36) Testis descend into scrotum & epididymus develops Week 37-40) Processus vaginalis closes

Question 23

What is it called if the testis do not descend through the processus vaginalis into the scrotum?

Answer 23

Cryptorchidism = sterility because normal testicular function requires a temperature lower than body temperature.

Question 24

Fluid accumulation in processus vaginalis

Answer 24

Hydrocele

Question 25

2 factors that maintain proper temperature for spermatogenesis

Answer 25

Cremaster muscle suspends it and contracts, relaxes as needed. Cooled by venous pampiniform plexus.

Question 26

What is the sperms pathway out of the testes?

Answer 26

Seminiferous tubules -> Straight tubules (Sertoli-like, epithelium only) -> Rete testis (epithelium w/microvilli only in mediastinum testes) -> Ductuli efferent (pseudo stratified columnar ciliated epithelium surrounded by thin layer of smooth muscle) -> Head of epididymis (stereo cilia on pseudo stratified columnar w/circular muscle layers, highly coiled, spermatozoa mature here) -> Stored in tail of epididymus -> Sympathetic stimulation sends them out the vas deferens (star shaped, pseudo stratified stereo cilia w/muscle) -> up the spermatocord -> through the inguinal canal -> enters pelvis through deep inguinal ring -> joins seminal vesicles -> ejaculatory duct in prostate -> urethra

Question 27

How long does it typically take for a spermatogonia to develop into a spermatozoa?

Answer 27

74 days

Question 28

What is Leydig secretion of testosterone dependent on?

Answer 28

Interstitial cell stimulating hormone (ICSH) from the anterior pituitary, an analogous hormone to LH in females

Question 29

How is the muscle layer of the vas deferens arranged?

Answer 29

Thick outer longitudinal layer + inner circular layer + thin inner longitudinal layer

Question 30

High folded tubes, walls appear to have pockets or cysts, pseudo stratified columnar epithelium with smooth muscle walls.

Answer 30

Seminal vesicles.

Question 31

What is the function of the seminal vesicles?

Answer 31

To make the semen rich in fructose and prostaglandins that is released by contractile force during ejaculation with the sperm

Question 32

Tubulo-alveolar glands, columnar to cuboidal epithelium surrounded by a fibroelastic capsule and smooth muscle.

Answer 32

Prostate gland.

Question 33

What does the prostate make?

Answer 33

Enzymes (like prostate specific acid phosphatase, PSA and fibrolysin) and citrate that are expelled from the prostate gland lumen into the urethra and decrease semen viscosity after ejaculation.

Question 34

Tubuloalveolar mucus glands

Answer 34

Bulbourethral glands, lubricate the urethra prior to ejaculation

Question 35

How does an erection occur?

Answer 35

ACh stimulates endothelial NO and VIP production -> smooth muscle makes cGMP -> vasodilation -> corpora cavernosa and spongiosum fill with blood. These are surrounded by a fibrous capsule, tunica albuguinia, that compresses the venous return. This results in erection.

Question 36

How does sildenafil maintain an erection?

Answer 36

It blocks PDE5 breakdown of cGMP and it is around longer to relax the smooth muscle

Question 37

How does ejaculation terminate an erection?

Answer 37

Sympathetic stimulation causes contraction of trabecular smooth muscle in the helical arteries and blood can leave