Hellekant - Spermatogenesis Flashcards

1
Q

Compared to oogenesis, what is a big difference with spermatogenesis?

A

Spermatogenesis occurs throughout life - both mitosis and meiosis occur through adult life

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2
Q

What is the ploidy, chromosome, DNA copy and chromatid numbers of spermatogonium?

A

2N, 46 chromosomes; 2C DNA, and 46 chromatids

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3
Q

What process is entered by spermatogonium?

A

Spermatocytogenesis (mitosis)

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4
Q

What is the ploidy of the primary spermatocyte?

A

Diploid - 2N

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5
Q

What is the number of chromosomes in a primary spermatocyte?

A

46 chromosomes

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6
Q

How many DNA copies does a primary spermatocyte have? Chromatids?

A

4 copies, 2x46 chromatids

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7
Q

What process does a primary spermatocyte enter?

A

Meoisis I

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8
Q

How may secondary spermatocytes are made from a primary spermatocyte?

A

Two

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9
Q

What is the ploidy of a secondary spermatocyte?

A

Haploid (N)

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10
Q

How many chromosomes does a secondary spermatocyte have?

A

23

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11
Q

How many copies of DNA does a secondary spermatocyte have?

A

2 copies

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12
Q

How many chromatids does a secondary spermatocyte have?

A

2x23 chromatids

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13
Q

What process does a secondary spermatocyte enter?

A

Meiosis II

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14
Q

How many spermatids are produced from the two spermatocytes?

A

Four

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15
Q

What is the ploidy of the spermatids?

A

Haploid

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16
Q

How many chromosomes does the spermatid have?

A

23 chromosomes

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17
Q

How many copies of DNA does a spermatid have?

A

One copy

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18
Q

How many chromatids does does a spermatid have?

A

23

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19
Q

In regards to the seminiferous tubules, where are Sertoli cells found? Germ cells? Leydig cells?

A

Sertoli and germ cells reside within the seminiferous tubules; Leydig cells reside outside the tubule

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20
Q

In regards to sertoli cells, where does spermatogenesis occur?

A

Between the sertoli cells

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21
Q

What is a spermatogenic wave?

A

Time it takes for the reappearance of the same stage within a given segment of the seminiferous tubule

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22
Q

How long is mitosis of spermatogonia?

A

16 days

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23
Q

How long is the first meiosis in spermatogenesis? Second meiosis?

A

24 days; second meiosis few hours

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24
Q

How long does spermiogenesis take?

A

24 days

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25
Q

How long is the approximate cycle of spermatogenesis?

A

64 days

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26
Q

In sperm production, what cells are most sensitive to drugs or environmental conditions?

A

Spermatocytes

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27
Q

What cells secrete inhibin? What is the action of inhibin?

A

Sertoli cell; inhibin has negative feedback on FSH

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28
Q

What cells phagocytize defective sperm?

A

Sertoli cells

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29
Q

What are the targets of testosterone?

A

Muscle, seminal vesicle, epididymis, bone

30
Q

What tissues produce 5 alpha reductase?

A

Prostate, external genitalia, skin

31
Q

What cells produce 95% of testosterone in men?

A

Leydig cells

32
Q

As men age, what happens to testosterone levels?

A

Total and free testosterone levels decrease

33
Q

Low testosterone levels in men result in what physical exam findings?

A

Increased abdominal fat, lower muscle mass

34
Q

Where is sex hormone binding globulin made?

A

Live, also in Sertoli cells (called androgen binding globulin)

35
Q

Testicular androgens are retained locally at high levels, how? What effect does this have?

A

Androgen binding protein maintain high levels; important/required for spermatogenesis

36
Q

Testicular androgen secretion require an intact pulsatile hypothalamic pituitary gonadal axis, how does this differ from administration of exogenous androgens?

A

Administration of exogenous androgens promote suppression of the gonadal axis

37
Q

What anabolic effects do androgens have?

A

Muscle building, bone growth and closure of epiphysis, sodium and water retention

38
Q

Normal production of androgens promotes the health and function of what? (Name 6)

A

Prostate, lower voice, external genitalia, genital tract, hair growth patterns, seminal vesicle

39
Q

Utilization of exogenous androgens has what androgenic effect?

A

Shuts down the gonadal axis

40
Q

Exogenous androgens shut down the gonadal axis, what effect does this have on the hypothalamic-gonad axis?

A

Hypogonadism (low androgen production), hypopituitary function, antifertility (endogenous testosterone is shut down; sperm count decreases)

41
Q

What anabolic effects are seen in exogenous androgen analogs?

A

Muscle building - promotes protein synthesis in muscles (counters glucocorticoid effects)

42
Q

What type of androgen ratio is preferred for anemia, osteoporosis, protein loss following trauma, surgery or prolonged immobilization?

A

High anabolic: androgenic ratio

43
Q

What is methyl testosterone?

A

Testosterone analog with c17 alkyl substitution

44
Q

What is oxandrolone?

A

DHT derivative; cannot be converted by aromatase

45
Q

Androgen therapy increases risk for what cancer?

A

Hepatic carcinoma

46
Q

If the goal is to shut down hypothalamic-pituitary-gonadal axis, what drugs should be used?

A

GnRH agonists/antagonists

47
Q

If the goal is to reduce androgen receptor signaling in the prostate, what drugs are used?

A

Androgen receptor antagonists, 5 alpha reductase inhibitors, or GnRH antagonists

48
Q

What durg is used to reduce excessive sexual drive in men?

A

Medroxyprogesterone acetate

49
Q

What is medroxyprogesterone acetate used for?

A

Androgen antagonist in men; used to reduce excessive sexual drive in men

50
Q

What is bicalutamide?

A

Nonsteroid, pure androgen receptor antagonist

51
Q

What is flutamide?

A

Nonsteroid, pure androgen receptor antagonist

52
Q

What is Nilutamide?

A

Nonsteroid, pure androgen receptor antagonist

53
Q

What are bicalutamide, flutamide, or Nilutamide used for?

A

Advanced prostate cancer

54
Q

What are the SEs of bicalutamide, flutamide, nilutamide?

A

Gynecomastia, hepatotoxicity

55
Q

What is the typical scenario using bicalutamide?

A

Add GnRH agonist (or orchidectomy)

56
Q

What is Gonadorelin?

A

GnRH agonist

57
Q

What is gonadorelin used for?

A

Functional assessment of gonadal response; male infertility (improves sperm number)

58
Q

What is Leuprolide?

A

GnRH agonist used in men

59
Q

What is Leuprolide used for?

A

Castration for cancer; gonadotropin dependent precocious puberty

60
Q

What is Degarelix?

A

GnRH antagonist

61
Q

What is Degarelix used for?

A

Advanced prostate cancer; male chemical castration; BPH,

62
Q

What is the MOA of finasteride?

A

5 alpha reductase inhibitors; inhibit conversion of testosterone to DHT

63
Q

What hormone is important in the growth and maintenance of the prostate gland?

A

DHT - dihyrdotestosterone

64
Q

What is finasteride used for?

A

BPH, prostate CA, male patterned baldness

65
Q

What is the MOA of dutasteride?

A

5 alpha reductase inhibitor - inhibits conversion of testosterone to DHT

66
Q

In an erection, what causes the production of nitric oxide?

A

Parasympathetic stimulation

67
Q

What are the effects of nitric oxide in the penis?

A

NO increases intracellular cGMP, cGMP promotes vasodilation, which causes penile engorgement

68
Q

What is the function of phosphodiesterase 5?

A

Degrades cGMP, therefore decreases vasodilation in the penis (lose erection)

69
Q

What drugs inhibit phosphodiesterase 5?

A

Sildenafil, vardenafil, tadalafil

70
Q

What is the MOA of sildenafil?

A

PDE 5 inhibitor

71
Q

What are the SEs to PDE-5 inhibitors?

A

HA, flushing, dyspepsia, nasal congestion

72
Q

What drug class can be used for hair follicle growth?

A

5 alpha reductase inhibitors