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Physiology final exam > Topic 87 - Male genitals, hormone regulation in the male reproductive system, spermatogenesis > Flashcards

Topic 87 - Male genitals, hormone regulation in the male reproductive system, spermatogenesis Flashcards

1
Q

Words to include in male genitals

A
  • Internal male genitals
    • Testes
      • Sperm
      • Sex hormones
    • Epididymis
      • Sperm maturation
    • Ductus deferens
      • Mature sperm from epididymis → urethra
    • Accessory seminal gands
      • Seminal vesicle (60% seminal fluid)
      • Protstate gland (30% seminal fluid)
  • External male genitals
    • Penis
    • Prepuce
    • Muscles
      • Protrusion
      • Erection
      • Ejaculation

Role of male reproductive system

  • Spermatogenesis
  • Spermatozoa
  • Ejaculation
  • 2nd sexual characteristics
    • Neuroendocrine control
      • Endocrine control
        • Androgens synthesized in thestes
        • Hypothalamo-pituitary control of secretion
      • Neural control
        • Formation of copulatory reflexes
          • Erection
          • Ejaculation
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2
Q

Words to include in hormone regulation in the male reproductive system

A
  • GnRH
  • Hypophyseal hormones
    • FSHLH (ICSH)
  • Peripheral hormones
    • Testosterone
    • Other androgens
    • Inhibin
  • Hypothalamus-hypophysis-gonad axis
    • Feedback mechanism

Testosterone

  • Lyding’s cells
  • Secretion
    • LH through hypothalamo-pituitary axis
    • LH-RH control
  • Blood & lymph
    • Diffuses across cell membranes
    • Accessory sex glands → androgen dependent tissues
    • Adluminal compartments of seminiferous tubule
      • Binds to ABP
        • Testosterone-ABP complex
          • Accessory sex glands
          • Androgen dependent tissues
      • Stimulate ABP production
        • Paracrine effect
  • DHT (Dihydrotestosterone)
    • Enter serotoil cells → metabolized to DHT
    • Bind to high-affinity androgen receptor
      • Maintains spermatogensis

Sertoil cells

  • Endocrine/paracrine function
    • Synthesis of ABP
    • Inhibin production
    • Estrogen
    • Müllerian inhibitory factor
      • Paracrine, endocrine and autocrine effect
  • Spermiocytogenesis
  • Spermiomorphogenesis
  • Acrosin (proteinase)
  • Acrosin binding protein (inhibitor)

FSH (Follicle Stimulating Hormone)

  • Interaction with sertoli cells
    • Stimulates ABP production
    • Stimulates spermiocytogenesis
      • Primary → secondary spermatocytes
    • FSH + LH + testosterone = Complets spermatogenesis
  • Conversion of testosterone
    • Dihydrotestosterone (DHT)
    • Estrogen
  • Completion of sperm release
  • Secretion of inhibin

LH (Leutenising hormone)

  • ICSH (Interstitial Cell-Stimulating Hormone)
  • Hyperthrophy of leydig cells
  • Stimulation of testosterone production by leydig cells
  • Endogenous testosterone production
    • Administration of LH or GnRH

Acrosin & acrosin-binding protein

  • Acrosin
    • Protease
  • Acrosin-binding protein
    • Inhibitor
  • Protein enabling penetration of oocyte by spermatozoa
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3
Q

Words to include in spermatogenesis

A
  • Germ cells
    • FSH
    • Testosterone
  • Continous supply of androgens
  • Spermatocytogenesis
    • Primordial germ cells → haploid spermatid
  • Spermiomorphogenesis
    • Haploid spermatid → spermatozoa
  • Golgi phase
    • Golgi complex → acrosomal granule → acrosomal vesicle at anterior of cell
    • Centrioles → axoneme
  • Cap phase
    • Acrosomal cap
      • Hydrolases
      • Proteinases
      • Hyaluronidae
      • Neuranidase
      • Acid phosphatase
  • Acrosomal phase
    • Spermatid re-orientation
    • Condensation of chromatin
      • Cell cytoplasm → cell posterior
  • Maturational phase
    • Residual cytoplasmic body sheds
  • Released spermatid
    • Peristalic movements of myoid cells
  • Final maturation
    • Motility
      • Flagellum
      • Lecithin cover
  • Complete cycle
    • 60-70 days

Blood-testis-barrier

  • Tight junctions
    • Serotoli cells
  • Spermatozoa
  • Immune system
  • Autoantigenic cells
  • Intratesticular sperm autoantigens
    • Immunoglobulin tolerance
    • Immunomodulatory mechanisms
      • Within testes
        • Steroids
        • Macrophages
        • Suppressor cells
    • Immunomodulation distal to testes
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4
Q

Topics to include in the essay

A
  1. Male genitals
    • Internal male genitals
    • External male genitals
    • Role of male reproductive system
  2. Hormone regulation in the male reproductive system
    • Hormonal regulation
    • Paracrine effects
    • Sertoli cells
    • Testosterone
    • FSH
    • ABP
    • Inhibin
    • MIF
    • LH
  3. Spermatogenesis
  4. Blood-testis-barrier
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5
Q

Male genitals

List the male genitals

A
  • Internal male genitals:
    • ​Testes
      • ​Produce sperm and sex hormones
    • Epididymis
      • ​Point of sperm maturation
    • Ductus deferens
      • ​Carry mature sperm from epididymis → urethra
    • Accessory seminal gland
      • ​Seminal vesicle (60% of seminal fluid​)
      • Prostatae gland (30% of seminal fluid)
  • External male genitals:​
    • Penis
    • Prepuce
    • Muscles for protrusion, erection and ejaculation
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6
Q

Give the role of male reproductive system

A
  • Spermatogenesis
  • Storage of spermatozoa
  • Ejaculation
  • Development and maintainance of 2nd sexual characteristics:
    • ​Coordinated nueroendocrine control
      • ​Endocrine control:
        • ​Andorens synthesized in testes
        • Secretion under hypothalao-pituitary control
      • Neural control:
        • ​Formation of copulatory reflexes
          • ​Erection
          • Ejaculation
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7
Q

Hormone regulation in the male reproductive system

List the hormones

A
  • GnRH
  • Hypophyseal hormones
    • ​FSH
    • LH
  • Peripheral hormones
    • ​Testosterone
    • Other androgens
    • Inhibin
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8
Q

Hormone regulation in the male reproductive system

FSH

A

FSH effects on sertoli cells

  • Production of ABP
    • ​Androgen Binding Protein → testosterone → stimulates in paracrine manner → ABP binds to testosterone and helps its transport to epididymis
  • Conversion of testosterone to dihydrotestosterone (DHT) and estrogen
  • Stimulation of spermiocytogenesis
    • Conversion from p​rimary spermatocytes → secondary seprmatocytes
      • ​Happens only if FSH is present
  • Completion of sperm release
  • Secretion of inhibin
    • ​Negative feedback action of FSH release (GnRH)
    • Paracrine effect:
      • ​Increasing speramtogenesis
      • Activation of aromate enzymes
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9
Q

Hormone regulation in the male reproductive system

LH

A
  • Other name: ICSH (Interstitial cell-stimulating hormone)
  • Results in hyperthrophy of Leydig cells
  • Stimulates production of testosterone by leydig cells
  • If administrated, LH or GnRH stimulate endogenous testosterone production
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10
Q

Hormone regulation in the male reproductive system

Testosterone

A
  • Produced by leyding cell
  • Passes freely across cell membranes
    • Enters blood and lymph
      • ​Causing negative feedback at hypothalamus which inhbibits LH release​
  • Some testosterone enters the adluminal compartments in the seminiferous tubules
    • ​When crossing the basal membrane, testosterone is bound to ABP
    • Testosterone-ABP complex serves to carry to the accessory sex glands and androgen dependent tissues
  • Some testosterone entering the sertoli cells may be metabolized to the more potent DHT (dihydrotestosterone)
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11
Q

Hormone regulation in the male reproductive system

Inhibin

A
  • Paracrine effect
    • Activates aromatase enzymes in sertoli cells
      • ​Testosterone estrogen conversion ↑
    • Spermatogenesis ↑
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12
Q

Hormone regulation in the male reproductive system

ABP

A
  • Produced by sertoli cells due to paracrine effect of testosterone
  • ABP binds to testosterone = testosterone-ABP complex​
    • ​Transports testosterone to epididymis for maturation of spermatozoa
  • Converts testosterone to dihydrotestosterone (DHT) and estrogen
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13
Q

Hormone regulation in the male reproductive system

Sertoli cells

A
  • FSH stimulates their activity
  • Major function:
    • Spermiocytogenesis
    • Spermigenesis
  • Hormones and other factors:
    • Estrogen
    • Inhibin
    • Dihydrotestosterone (DHT)
    • Androgen Binding Protein (ABP)
      Müllerian Inhibitory Factor (MIF)

​Summary of endocrine/paracrine role:

  • ABP synthesis
  • Inhibin production
    • ​Paracrine effect
    • Autocrine and endocrine action
      • Negative action on FSH and GnRH
  • Estrogen
    • ​Produced in sertoli cells by conversion of testosterone
  • Müllerian Inhibitory Factor
    • ​Helps development towards male gender in embryonic life
    • Paracrine, endocrine and autocrine action
    • Negative action on pituitary FSH
    • Positive action on LH production
  • Acrosin (proteinase) and its inhibitor acrosin binding protein are synthesized in serotoli cells
    • ​Key enzyme of penetration of spermatozoa
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14
Q

Hormone regulation in the male reproductive system

Hormonal regulation, figure

A
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15
Q

Hormone regulation in the male reproductive system

Paracrine effects

A
  • Testosterone
    • ​Stimulates ABP production in the tubules
  • Inhibin
    • ​Activates aromatase enzymes in sertoli cell
      • ​Testosterone estrogen conversion ↑
    • Spermatogenesis ↑
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16
Q

Spermatogenesis

​

A
  • Can only be completed when both FSH and testosterone can reach layer of germ cells
  • Most stages of spermatogenesis require continuous supply of androgens
  1. Spermatocytogenesis:
    • Primordial germ cell → haploid spermatid
    • ​Mitosis
      • ​Type A spermatogonium
      • Type B spermatogonium
    • Meiosis
      • ​Spermatocytes I-II
  2. Spermiomorphogenesis: haploid spermatid → spermatozoa
    • ​Spermatid
    • Sperm (spermatozoa)

​Phases of spermiomorphogenesis:

  1. Golgi phase​
    • ​Golgi complex → acrosomal granule → acrosomal vesicel at anterior of cell
    • Centrioles → axoneme (central portion of “tail”)
  2. Cap phase
    • ​Acrosomal cap develops over nucleus
    • Chromatin condense
    • Flagellum develops from axoneme
  3. Acrosomal phase
    • Spermatid re-orientates
    • Further chromatin condensation​
  4. Maturational phase
    1. Residual cytoplasmic body sheds
    2. Cell linkage lost
    3. Cell released into lumen of tubule
  5. Released spermatid
    1. ​Move in fluid according to peristaltic movements of myoid cells
  6. Final maturation
    1. Sperm gain motlity of flagellum and lecithin cover​
  7. Complete cycle​
    1. ​60-70 days

Figure: spermatogenesis

Physiology final exam (111 decks)

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