Endocrinology of the Male

Question 1

Do males have a surge or tonic center? Why or why not?

Answer 1

Males only have a tonic center because estrogen defeminizes the surge center; the surge center is also not important to males, because it is only appropriate for the GnRH surge and driving the LH surge for CL formation, oocyte formation, etc. which is only needed in the female

Question 2

What are the LH surge patterns in males?

Answer 2

LH surges with a subsequent surge of testosterone, which cycles and continues in this pattern

Question 3

Is GnRH important for males?

Answer 3

yes. after binding the gonadatropins in the anterior pituitary, GnRH causes a release of both LH and FSH.

Question 4

Importance of LH in males?

Answer 4

it causes testosterone production by the Leydig cells, which once produced is released into the general circulation and has a negative feedback at the level of the hypothalamus and pituitarty to control the amount of GnRH and LH that is released.

Question 5

why is the negative feedback loop of testosterone important?

Answer 5

it regulates how much testosterone is being produced by those Leydig cells that are in the interstitial space in the testis

Question 6

What is another function of testosterone for when it enters the ST?

Answer 6

it is important for sertoli cell function and for promoting the further development of those spermatagonial cells (early pre-sperm cells)

Question 7

how is testosterone transported to the epididymis?

Answer 7

it gets into the lumen of the ST, binds with androgen binding protein which allows it to be transported to the epididymis and further needed to regulate the function of the epididymal cells

Question 8

Why is FSH important?

Answer 8

from the anterior pituitary, it is important in terms of sertoli cells: binding receptor of sertoli cells, important for tight junctions to form between sertoli cells, forming a microenvironment important for spermatagenesis; causes production of inhibin by sertoli cells to regulate how much FSH is released by AP; sertoli cell produces ABP; binds testosterone in ST to take out and get it to epididymis; allows for production of estradiol

Question 9

Where is testosterone produced in the female?

Answer 9

theca interna cells

Question 10

Where is testosterone produced in the male?

Answer 10

Leydig cells, but then travels to the sertoli cells under the influence of FSH that testosterone is aromatized via the enzyme aromatase to estradiol

Question 11

What does testosterone get aromatized to?

Answer 11

estradiol

Question 12

What is produced under the influence of FSH?

Answer 12

inhibin which has a negative feedback at the AP where some estradiol has a negative feedback to AP and hypothalamus

Question 13

What is the relationship between GnRH, LH, and FSH?

Answer 13

release of GnRH, shortly after, a release of LH which regulates FSH release (small peaks of FSH at high surge peaks of LH with small peaks of GnRH just before the LH surge and FSH peaks)

Question 14

Which hormone plays a role in the release o testosterone from the Leydig cells?

Answer 14

LH (it surges and regulates the release of surges of testosterone

Question 15

spermatogenesis?

Answer 15

the process of producing spermatazoa; sum of all cellular transformations in developing germ cells in ST

Question 16

Where do spermatic cells progress in the ST as they increase in maturity?

Answer 16

the lumen

Question 17

What shape are early sperm cells?

Answer 17

round

Question 18

What will sperm cells closest to the lumen resemble?

Answer 18

sperm with head and tail unlike early sperm cells (round)

Question 19

myoid cells?

Answer 19

muscle like cells that facilitate movement of sperm out of lumen of ST

Question 20

What are the three phases of spermatogenesis?

Answer 20

Proliferation, meiosis, differentiation

Question 21

proliferation phase?

Answer 21

starts with early primitive cells that undergo mitotic divisions (proliferation) and at some point they have to enter and complete meiosis to become the haploid gamete required to meet up with the oocyte; this is the time period where sperm cells undergo a series of mitotic divisions (spermatocytogenesis)

Question 22

Meiosis phase?

Answer 22

time period after mitotic divisions stop and germ cells enter into meiosis and sperm (once they start) complete it - unlike oocytes

Question 23

differentiation phase?

Answer 23

round cells undergo a metamorphasis and become like the cell type (easily identifiable) that has an elongated head and a tail (spermiogenesis)

Question 24

spermatocytogenesis?

Answer 24

time period where early spermatagonia goes from this stage up to the primary spermatocyte; stage capable of initiating meiosis

Question 25

Are mitotic divisions species specific?

Answer 25

yes, usually between 2-6 divisions with potential daughter cells ranging from 4-64

Question 26

what are spermatic cells are connected by?

Answer 26

cytoplasmic bridges with allow the cells to communicate and ensures that the sex ratio remains around 51% males, 49% females

Question 27

meiosis?

Answer 27

production of haploid gametes beginning with the spermatocytes and ending with round spermatids

Question 28

Difference between meiosis in males and females?

Answer 28

in males, meiosis doesn't stop, it gets completed. In females, it stops twice

Question 29

Where does DNA synthesis occur in meiosis?

Answer 29

the S phase

Question 30

What cell types are present in the gap phase?

Answer 30

primary spermatocytes and primary oocytes (diploid cells)

Question 31

At what point do the diploid cells each split into two copies to where the cell is 4N?

Answer 31

s phase

Question 32

Before entering DNA synthesis, cells switch from __ to __.

Answer 32

mitosis to meiosis

Question 33

5 phases of prophase in meiosis?

Answer 33

leptotene, zygotene, pachytene, deplotene/dictyate, diakinesis

Question 34

leptotene phase?

Answer 34

chromosomes condense 1st phase

Question 35

zygotene?

Answer 35

homologous chromosomes begin to pair: phase 2

Question 36

pachytene?

Answer 36

pairing is completed; crossing over of homologues (recombination): phase 3

Question 37

diplotene/dictyate?

Answer 37

homologous chromosomes pull apart but remain attached at crossover points (chiasma), RNA synthesis is possible, oocytes arrest here until LH surge or other stimulus initiates resumption of meiosis phase 4

Question 38

diakinesis?

Answer 38

transition to metaphase; chromosomes recondense, RNA synthesis stops, not as distinct in males: phase 5

Question 39

Metaphase I?

Answer 39

homologous chromosomes move toward opposite poles and pair across from one another, homologous chromosome held together by chiasma

Question 40

Anaphase I?

Answer 40

begin to pull apart and are different from before as a result of recombination of crossing over

Question 41

Telophase I?

Answer 41

(cytokinesis); secondary spermatocyte; in oocyte extruded as polar body (only 1 copy of chromosomes), but in males you get two cells that look the same (with 2 copies of chromosomes)

Question 42

Metaphase II?

Answer 42

secondary spermatocytes formed (oocytes stop here until fertilized but sperm continues)

Question 43

Anaphase II?

Answer 43

completion of meiosis

Question 44

end result of meiosis?

Answer 44

fours cells from the first one that entered with each having a unique set of chromosomes

Question 45

All phases of meiosis in order?

Answer 45

prophase, metaphase I, anaphase I, telophase, metaphase II, anaphase II

Question 46

spermatogenesis vs oogenesis?

Answer 46

each has a unique set of chromosomes that can contribute to the genome of the zygote, assuming it gets fertilized; the oocyte while it is sitting to be fertilized has two and it doesn't become haploid until after fertilized by the sperm and a series of things occurs for it to get rid of the second polar body

Question 47

spermiogenesis?

Answer 47

round spermatids are transformed to spermatozoa in four phases

Question 48

What are the four phases of spermiogenesis (differentiation)?

Answer 48

golgi, cap, acrosomal, maturation

Question 49

What three things occur during spermiogenesis?

Answer 49

nucleus becomes highly condensed, acrosome forms, cells become potentially motile (tail forms and acquire of metabolic power plant which provides fuel for driving and allowing motility

Question 50

golgi phase?

Answer 50

acrosome development, migration of centrioles; small golgi vesicles fuse giving rise to larger secretory proacrosomic granules; proximal and distal centrioles migrated which gives rise to the tail (flagellum)

Question 51

Function of proximal centriole?

Answer 51

allows flagellum to be anchored to the nucleus

Question 52

Function of distal centriole?

Answer 52

gives rise to developing axoneme (central part of flagellum)

Question 53

cap phase?

Answer 53

acrosome forms a distinct cap over anterior portion of nucleus; primitive flagellum from distal centriole begin to elongate; golgi migrates to caudal part of the cell; distal centriole forms axoneme or flagellum and begins to elongate; acrosomic vesicle flattens to form a distinct cap by spreading over the nucleus and allowing it to elongate

Question 54

acrosomal phase?

Answer 54

acrosome continues to spread until it covers 2/3 of anterior nucleus; nucleus begins to elongate (shifted to one part of the cell); manchette froms (unique system of microtubules) and attaches just posterior to acrosome

Question 55

maturation phase?

Answer 55

manchette disappears; mitochondria migrate to cluster around flagellum; assembled from nucleus base to anterior 1/3 of tail; form mid-piece; dense outer fibers of flagellum and fibrous sheath are formed; assembly is completed

Question 56

where is ATP produced?

Answer 56

in the middle piece

Question 57

Where is mitochondria located?

Answer 57

in the middle piece

Question 58

function of the neck?

Answer 58

anchors the tail to the head of sperm

Question 59

spermiation?

Answer 59

once metamorphasis is complete, spermatozoa is release from the sertoli cells to the lumen; most cytoplasm stays and is not release as part of sperm and remains is the sertoli cells to be phagosotized

Question 60

sertoli cells = ?

Answer 60

nurse cells

Question 61

cytoplasmic droplet?

Answer 61

remnants of cytoplasm that remains; moves farther down sperm tail as it increases in maturity

Question 62

where is sperm not motile and not fertile?

Answer 62

epididymal head (proximal CD)

Question 63

where does sperm have some motility and fertility and can bind to the ova?

Answer 63

epididymal body (translocation CD)

Question 64

Where is sperm motile, fertile, and can bind to ova?

Answer 64

epididymal tail (distal CD)

Question 65

Sperm cell types in order?

Answer 65

spermatogonia, primary spermatocyte, secondary spermatocyte, round spermatid, spermatozoa

Question 66

After spermiation where does the spermatozoa enter?

Answer 66

rete testis to make its way out and continue progression

Question 67

4 reasons for sertoli cells importance?

Answer 67

support for germ cells, environment for germ cell development and maturation, initiates meiosis, hormonal signals affect the AP (think of sertoli cells as jello)