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END 207: Physiology > Male 1: Testicular compartment, Spermatogenesis > Flashcards

Male 1: Testicular compartment, Spermatogenesis Flashcards

1
Q

Describe spermatogenesis

A
  1. Mitosis:
    primary spermatogonia –> Secondary spermatogonia (diploid)
  2. Seconadry spermatogonia increases in size –> Primary spermatocyte
  3. 1st mieotic division:
    Primary spermatocyte —-> secondary spermatocyte (Haploid)
  4. Second Mieotic division (actually mitosis):
    Spermatocyte –> Spermatid (same haploid)
  5. Spermiogenesis: Spermatid matures and acquires motility in the epididymis —> Spermatozoa
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2
Q

complete cycle of Spermatogenesis take about ___

A

64 days

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3
Q

Single primary spermatogonia gives rise to ____ spermatids/spermatozoa

A

512

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4
Q

Importance of Joined cytoplasmic bridges between developing germ cells arising from same 1ry spermatozoa

A

so that cells containing X chromosomes share essential products that dont exist in Cells containing Y chromosomes

otherwise, Y chromosomes containing cells would die

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5
Q

Progressive motility of spermatozoa depends on:

A
  • Activation of CatSper ptn: Alkaline sensitive cation, which is more active at Cervical mucous pH=8 –> allows cAMP calcium influx
  • Chemotaxis: they have olfactory receptors to odor like chemicals produced by ovary
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6
Q

Describe capacitation

A

exposure of sperm to female genital tract make it able to fertilize, by:
* Increasing its motility (catsper ptn & Chemotaxis)
* Preparation for acrosomal reaction

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7
Q

Importance of Capacitation

A

facilitatory more than obligatory, as fertilization could occur in vitro

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8
Q

Deficiency in spermatozoa ACE (Angiotensin converting enzyme) leads to:

A

Infertility

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9
Q

Enumerate importances of Sertoli cells

A
  1. Provide nutrinets (glycogen) & physical support to maturing germ cells
  2. Phagocytosis of debris from spermatogenesis
  3. Secretion of important substances for spermatogenesis
  4. Formation of blood-testis barrier
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10
Q

Substances secreted by Sertoli cells:

A
  • MIS (mullerian inhibitory substance)
  • Activin –> Stimulate FSH
  • Inhibin —> Inhibits FSH
  • ABP (Androgen Binding protein) —> maintain high androgens in tubular fluid by keeping constant concentration
  • Aromataze –> Converts androgen to estrogen
  • Estrogens
  • Proteolytic enzymes
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11
Q

Function of proteolytic enzymes secreted by Sertoli cells

A

helps progression of developing germ cells towards the lumen

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12
Q

Explain how tubular fluid is different in composition from plasma

A
  • Very little protein
  • Very little glucose
  • High androgens & estrogens
  • Aspartic & glutamic acids
  • Inositol
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13
Q

Explain how spermatozoa remain concentrated in Tubular fluid

A

via estrogen:
1. Estrongen binds to estrogen receptor Alpha
2. Increases reabsorption of water

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14
Q

Substances prevented to pass by Blood-testis barrier

A
  • Antigeneic products from spermatogenesis to blood –> prevent autoimmune reaction
  • Harmful blood agents into tubular lumen
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15
Q

Substances Allowed to pass by Blood-testis barrier

A
  • Steroid
  • Maturing germ cell (it has to break tight junctions created for blood-testis barrier in order to progress towards the lumen)
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16
Q

Function of LH in Spermatogenesis

A

Acts on Interstitial cells of Lyedig —> produce more Androgens (testosterone) to maintain spermatogenesis

17
Q

Function of FSH in Spermatogenesis

A
  • Sensitizes Leydig cells to LH by facilitating more LH receptors
  • Promotes production of ABP (androgen binding protein)
  • Acts on Sertoli cells in late stage spermatid maturation
18
Q

Function of Activin & Inhibin

A

regulate FSH secretion

19
Q

Androgens acting on sertoli cells is important for:

A
  • Maintainace of germinal epithelium
  • to complete miotic divisions
  • early stage of Spermogenesis (spermatid –> spermatozoa) as it is Androgen dependent
20
Q

Androgen levels are kept high locally for spermatogenesis by:

A
  • Counter current exchange
  • Androgen binding protein (ABP)
  • High number of Leydig cells
21
Q

other hormones important for Spermatogenesis

A
  • Growth hormone (for early)
  • prolactin (for early)
  • Thyroixine
  • Leptin (for start)
  • Estrogen (mediate actions of FSH)
22
Q

Explain how optimum temperature of 35 for spermatogenesis is aquired:

A
  • Absence of subcutaneous fat in scrotum
  • if weather is cold, dartos muscle contrats to proximate testis towards body
  • Scortum is located outside abdominal cavity
23
Q

Factors inhibiting Spermatogenesis

A
  • X ray/irradiation (irreversible but leydig cells still secrete tetosterone)
  • bacteria
  • Chemical toxins
  • Prolonged fever
  • hot baths more than 40 degrees for more than 30 mins
  • Tight pants
24
Q

Balanced diet vital for Spermatogenesis should contain:

A
  • Zinc
  • Selenium
  • Vit A,B,C,E
25
Q

Factors may increase sperm count

A

Seasonal –> increase in winter

END 207: Physiology (20 decks)

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