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ANIMAL PRODUCTION - Reproduction > 3 – Male Reproductive System I > Flashcards

3 – Male Reproductive System I Flashcards

1
Q

Sperm journey

A
  1. High speed manufacturing
  2. Nuclear and flagellar stabilization, motility (head and body of epididymis)
  3. Warehouse and shipping (tail of epididymis)
  4. Final alteration and packaging
  5. Delivery system
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2
Q

Thermoregulation of testis

A
  • 4-6 degrees C cooler than body
  • Short periods of high temperature is probably tolerated
    o If more than 8 hours = reduce sperm MOTILITY and cause DNA damage
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3
Q

Cooling is a function of

A

> creamster muscle
scrotal skin
tunica dartos (lots of SM fibers)
vascular countre-current (pampiniform flexus)

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4
Q

Pampiniform plexus

A
  • Venous network wrapped around the testicular artery
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5
Q

Pampiniform plexus has an effect in:

A

o Heat exchange
o Pulse pressure reduction
 Pulse over time could cause damage to testes
 Mechanism is not clear
 *maybe the testicular artery is more elastic?
o Transfer of testosterone

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6
Q

Rete testis

A
  • Pigs and bulls: central
  • Horses and humans: superficial
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7
Q

Leydig (interstitial endocrine) cells

A
  • Produce testicular androgens
    o Lots of estrogen in pig and horse
  • Occupies most volume in pigs
  • Large polymorphous acidophilic (pink) cells w/round nucleus
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8
Q

3 distinct Leydig cell populations

A
  1. Fetal Leydig
  2. Infantile/early postnatal Leydig
  3. Adult Leydig
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9
Q
  1. Fetal Leydig
A

a. Sex determination to shortly after birth

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10
Q
  1. Infantile/early postnatal Leydig cells
A

a. Only in some species
b. Very short-lived

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11
Q
  1. Adult Leydig cells
A

a. From puberty thru adult life

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12
Q

Seminiferous cords/tubules

A
  • Convoluted double-ended loops (2m in mice, 5kim in bulls)
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13
Q

Seminiferous cords/tubules consists of

A

o Lamina propria
 Made up of basal lamina surrounded by peritubular cells
o Sertoli cells
o Spermatogenic cells

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14
Q

Seminiferous cords

A

o Immature and lack a lumen
o 70-90um
o Sertoli and gonocytes (early generation of germ cells)

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15
Q

Seminiferous tubules

A

o More developed and have a lumen
o 150-300um
o Sertoli and multiple generation of germ cells

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16
Q

Peritubular myoid cells (PTMCs)

A
  • 1-5 layers of contractile cells surrounding the basal lamina
  • Contain abundant actin filaments and cytoskeleton proteins
  • Resemble myofibroblasts (ex. bull) or SM fibers (ex. boar)
  • *contractile action assists in propulsion of sperm and testicular fluid
    o Along seminiferous tubules toward rete testis
17
Q

Sertoli (sustentacular) cells

A
  • Oval nucleus w/prominent nucleolus near base
  • Adult cells differ and lose mitotic capability
  • Large elongated cells w/irregular outlines touching basal membrane
  • Even spaced in tubule
18
Q

Sertoli (sustentacular) cells ROLES

A

o Provide nutrients and signals to dividing germ cells
o Move germ cells along to lumen
o Secrete testicular fluid into lumen for sperm transport
o Phagocytize faulty germ cells and their excess cytoplasm
o Produce chemical mediators to regulate spermatogenesis

19
Q

Sertoli cells’ junctional complexes

A
  • Sertoli-Sertoli tight junction
  • Sertoli-spermatid junction
20
Q
  • Sertoli-Sertoli tight junction
A

o Between adjacent cells
o Forms blood-testis barrier
o Divides tubules into basal and adluminal compartments
o *opens like a zipper to allow germ cells to pass from basal to lumen

21
Q
  • Sertoli-spermatid junction
A

o Specialized with spermatid nucleus

22
Q

Gonocytes

A
  • Part of male GERMLINE stem cells
    o Come after primordial germ cells (PGCs)
    o Come before spermatogonia stem cells (SSCs)
  • Appear at 13.5dpc in rodents and 7wk of gestation in human embryos
    o Development is HORMONE-Independent
23
Q

Gonocytes appear when

A
  • Testis cords are formed
  • PGCs have lost alkaline phosphatase (AP) activity and adopted male germ cell fate
24
Q

Gonocytes classification

A
  • Mitotic fetal gonocytes
  • Quiescent gonocytes
  • Mitotic postnatal gonocytes
25
Q

Mitotic fetal gonocytes

A
  • Multiplying (M) prospermatogonia
  • Immediately after PGCs and before mitotic arrest
  • Proliferate from 13.5-18dpc in rodents, 18 weeks in humans
  • Become quiescent
26
Q

Quiescent gonocytes

A
  • Primary transitional (T1) prospermatogonia
  • Large round cells
  • 1-2 nucleoli in prominent nucleus
  • Start after mitotic arrest until 1-2 days (rodents) or weeks/months after birth
27
Q

Mitotic postnatal gonocytes

A
  • Secondary transitional (T2) prospermatogonia
  • In transition to A-spermatogonia (residing at basement membrane)
  • T1-prosp develop pseudopods, migrate to basement membrane, resume mitosis, differentiate into T2-prosp
    o Failure to develop pseudopods=apoptosis and maybe testitcular cancer in young men?
  • Start 1-4 days postnatally (rodents) or 8week after birth (humans)

ANIMAL PRODUCTION - Reproduction (17 decks)

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