8 Cell Bio Male Reproduction

Front 1

When does an undescended testicle need to be brought down surgically in order to preserve fertility? What, besides infertility, can happen if it is not done?

Back 1

Needs to be brought down within two years. If that is not done: very high incidence of cancer.

Front 2

What is optimal temperature for the testis? How is this achieved? What happens if it gets TOO cold?

Back 2

Optimal = 2 degrees below body temperature.

Veins form a plexus around the testicular artery (pampiniform plexus) which cools the blood. (“Countercurrent heat exchanger”)

If it falls to more than 2 below body temp, then the DARTOS MUSCLE and spermatic cord can contract to bring the testis closer to the abdomen.

Front 3

What is the tunica vaginalis?

Back 3

A single layer of mesothelium: Originally peritoneum that is displaced and brought down from the abdomen during the descent from the abdomen → allows the testis to “float around” in the scrotum.

Front 4

What is the term for the thick layer of connective tissue surrounding the testis and is surrounded by the tunica vaginalis?

Back 4

Tunica albuginea

Front 5

What is the pathway for sperm from maturation to ejaculation?

Back 5

SEVEN UP
Seminiferous tubules, epididymis, vas deferens, ejaculatory duct, n = “nothing” (I didn’t make this up), urethra, penis.

Front 6

True or false, sperm passes through the seminal vesicle?

Back 6

False. This is a misnomer → due to post-mortem artifact. In life, the seminal vesicle is just a gland. Sperm never enters.

Front 7

Where is sperm stored in preparation for ejaculation?

Back 7

There is a dilation (ampulla) of the vas deferens where it meets the seminal vesicle. It’s NOT stored in the seminal vesicle itself.

Front 8

What is the term for the place where the seminal vesicle and vas deferens meet?

Back 8

Ejaculatory duct.

Front 9

What are the accessory glands of the male reproductive system?

Back 9

Seminal vesicle, prostate, bulbourethral gland

Front 10

What is another term for the bulbourethral gland? What does it do?

Back 10

Cowper’s gland. Secretes mucous into ejaculate.

Front 11

What are the names of the erectile tissues of the penis? Where do they lie?

Back 11

Corpus cavernosum → two of them on the dorsal side
Corpus spongiosum → surrounds the urethra

Front 12

Germ cells are generated in the __________. Interstitial cells (aka _____ cells) secrete _________.

Back 12

Seminiferous tubules
Leydig
Androgens

Front 13

Leydig cells respond to _____, produce ______, which feeds back onto the hypothalamus to inhibit ______.

Back 13

LH
Testosterone
GnRH

Front 14

What two types of cells do you find in the seminiferous tubules? What hormone acts here?

Back 14

Sertoli (supporting) and Spermatogenic cells

FSH

Front 15

The seminiferous epithelium is divided into basal and luminal compartments. ______ are located on the basal side and _______ are luminal.

Back 15

Spermatogonia
Spermatids

Front 16

The ______ is the “school for sperm training.” How long do the spermatids spend there?

Back 16

Epididymis. 1-2 weeks (learning to swim)

Front 17

60% of fluid in semen is produced in the _________, while the rest is produced in the _______.

Back 17

Seminal vesicle
Prostate

Front 18

The seminiferous tubules are divided into incomplete compartments by the ______. The tubules drain through this into the _______. The ends of seminiferous tubules are called _______. Do these ends produce spermatozoa?

Back 18

Tunica albuginea
Rete testis (holes)
Straight tubules
No – they just deliver them

Front 19

Describe the efferent ducts: what do they do and how do they do it?

Back 19

Drain the testis. Have cilia that push the sperm out. Absorb water leading to a net outward flow. Deliver sperm to epididymis.

Front 20

The ______ is highly contractile. Where does the energy to “shoot” the sperm out come from?

Back 20

Vas deferens (also → ejaculatory duct)
Energy comes down via fructose from the seminal vesicle.

Front 21

The stem cells that give rise to the spermatozoa are called _______.

Back 21

Spermatogonia.

Front 22

What is one key way in which male and female gamete production differs (related to stem cells)?

Back 22

Male stem cells give rise to a sustained population of gamete precursors. Female has a finite number that is exhausted through maturation.

Front 23

How many sperm per ejaculate? When does sperm production end? What quantity would be considered male infertility?

Back 23

400 million

Usually ends in the 8th decade of life.

<25 million per ejaculate would be considered infertile.

Front 24

What are the five stages of spermatogenic cells, where are they located, what is their chromosome status, and what cell process does it undergo? Which is committed to differentiate?

Back 24

1.) Spermatogonia → basal → self-renewing mitotic
2.) Primary spermatocytes → basal to luminal → 4n, 1st meiotic division
3.) Secondary spermatocytes → luminal → 2n, 2nd meiotic division
4.) Spermatids → luminal → haploid, remodeling
5.) Spermatozoa → luminal → haploid,


Primary spermatocyte is committed to differentiate.

Front 25

Most of the cells you see in the testis deep to the spermatogonia are what type of spermatogenic cell and in what stage? How long does this stage last?

Back 25

Primary spermatocytes in prophase of the 1st meiotic division.

(Prophase takes 22 days)

Front 26

What is spermiogenesis?

Back 26

Remodeling of the spermatids (into sperm)
[Not to be confused with spermatocytogenesis]

Front 27

True or false, after the remodeling of spermatids, the sperm are ready for fertilization?

Back 27

False

Front 28

What is special about the seminiferous epithelium (compared to any other epithelium in the body)? How does this feature come about? Why is it necessary?

Back 28

The basal portion is separated from the luminal portion. This creates the blood-testis barrier, which is needed for immunological isolation of haploid cells. This is necessary because spermatids do not come about until puberty, after the body has already created its “immunologic inventory.” So a spermatid is seen as “foreign.” The barrier is the result of tight junctions between Sertoli cells.

Front 29

What are the stages of prophase that correlate with 1.) condensation? 2.) progression? 3.) packing and crossing over? What are the last two stages of prophase?

Back 29

1,) Leptotene
2.) Zygotene
3.) Pachytene

Also … diplotene and diakinesis

Front 30

Describe the S phase and prophase of secondary spermatocytes.

Back 30

S phase → absent! No DNA synthesis before division.
Prophase → very short. Division is immediate. No waiting period like with primary spermatocytes.

Front 31

Spermatogonium divide to form _________ or ___________.

Back 31

Another spermatogonium (self-replication)
Spermatocytes

Front 32

What is the role of the sertoli cell?

Back 32

Lifeline of the spermatocyte. Provide nutrition to the spermatocyte, which is quarantined from the rest of the body. Also: Take up the cytoplasm that must be disposed of when the spermatid grows its flagella and condenses to a swimming ball of DNA (spermiogenesis).

Front 33

What stage in cell division is incomplete in spermatogenic cells?

Back 33

Cytokinesis
Cells remain connected via cytoplasmic bridges. This keeps them in synchrony. So the cells go through the seminiferous tubules in waves.

(With the exception of spermatogonia, which do complete the division.)

Front 34

What happens during spermiogenesis?

Back 34

Golgi apparatus becomes very prominent and migrates to the opposite pole. Stops delivering proteins from endoplasmic reticulum by vesicles; it retains them and in doing so forms the acrosome.

Front 35

What is contained in the acrosome and what is its purpose?

Back 35

Proteolytic enzymes and hyluronidase
Enables sperm to dissolve mucous of the female reproductive system and “elbow their way through” to get to the follicle. Also, it can blast and dissolve the zona palucida.

Front 36

Gershon calls this the “flame thrower” of the spermatozoa.

Back 36

Acrosome

Front 37

Describe the spermatozoa from head to tail.

Back 37

Tip = acrosome (flame thrower)
Head = condensed DNA
Middle piece = “energy-producing factory” formed by centriole, wrapped in mitochondrial sheath
Tail = “motor” wrapped in fibrous sheath

Front 38

_______ have the look of a steroid producer. (Lots of lipoid crystals, lots of smooth ER, highly eosinophilic).

Back 38

Leydig cells

Front 39

_______ lie between seminiferous tubules and the rete testis.

Back 39

Tubuli recti

Front 40

This structure drains the tesis, resorb water, have weak pumping smooth muscle. True or false, this structure contains cilia?

Back 40

Efferent ductules
True

Front 41

How can you distinguish efferent ductules from epididymis?

Back 41

Efferent ductules: cilia, highly irregular

Epididymis: much more ordered, pseudostratified columnar epithelium, stereocilia

Front 42

Where do sperm learn to swim? How long do they stay there? Describe this area histologically.

Back 42

Epididymis: pseudostratified columnar epithelium, lined by stereocilia, large golgi (very secretory epithelium, sperm can be seen in the lumen

Sperm stay there 2-3 weeks

Front 43

What is the purpose of stereocilia in the epididymis?

Back 43

Sperm are in constant contact with the microvilli. They secrete material that “puts the sperm to sleep” → (b/c sperm are theoretically capable of moving after 24 hours, but they’re “kept quiet” for 2-3 weeks)

Front 44

What is special about the structure of the vas deferens that permits emission of sperm? What is responsible for emission (sympathetic or parasympathetic)?

Back 44

It has a very thick muscle coat (3 layers – inner longitudinal, middle circular, outer longitudinal). It contracts explosively under direction of sympathetic nervous system.

Front 45

What is the purpose of the ampulla? Where is it located?

Back 45

It is temporary storage of sperm in the vas deferens.

Front 46

True or false, the seminal vesicle has a thick muscular coat?

Back 46

True – like the vas deferens, it secretes explosively.

Front 47

_______ is a fibromuscular gland that just keeps on growing. What is the term for the overgrowth? Why is this a problem? What are two substances secreted by this gland (a common lab measurement)?

Back 47

The prostate
BPH : benign prostatic hypertrophy → causes occlusion of the prostatic urethra, which runs through the prostate.
PSA & Acid Phosphatase

Front 48

What is a common cause of prostatitis?

Back 48

The prostate contains concretions that often calcify, blocking the ducts and leading to prostatitis.

Front 49

Describe the processes leading to tumescence and detumescence.

Back 49

Tumescence: Parasympathetic innervation cause dilation of arteries and relaxation of smooth muscle (Ach causes NO release, which activates cGMP). Vascular spaces of cavernous bodies fill with blood. Fibrous sheath doesn’t giveway, so pressure makes penis erect.

Detumescence: smooth muscle contracts, A-V shunts open, pressure fales. cGMP is metabolized by cGMP specific phosphodiesterase 5.

Front 50

What is the target if sildenafil (Viagra)?

Back 50

cGMP specific phosophodiesterase 5; this enzyme normally catalyzes detumescence.

Front 51

What is the purpose of the internal urethral sphincter?

Back 51

Contracts to prevent retrograd ejaculation.

Front 52

What nerve mediates ejaculation? What is the trigger?

Back 52

Pudendal nerve
Triggered by emission