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Theriogenology VCS862 > Sperm Development > Flashcards

Sperm Development Flashcards

1
Q

Spermatozoa are produced in the …

A

seminiferous tubules of the testicles

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2
Q

Spermatogenesis involves

A

proliferation of stem cells

Meiotic division of stem cells starts near puberty

Differentiation from a nucleated round cell to the specialized tad-pole shaped sperm cell

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3
Q
A

bull sperm

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4
Q
A

rat sperm

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5
Q
A

dog sperm

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6
Q

Testicle

A

is made up largely of closely packed seminiferous tubules

90% of testicular tissue in bulls, rams, rats; to as low as 60% of testicular tissue in boars and stallions

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7
Q

Leydig cells

A

Testosterone producing cells

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8
Q

Sperm development

Pathway

A

the most immature cell types are located at hte periphery of the tubule

As cell mature they move toward the lumen

Once mature, they are released into the lumen for transport to the epididymis for maturation and storage

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9
Q

Path from seminiferous tubules → vas deferens

A

Seminiferous tubules → rete testis → efferent ducts → epididymis → Vas deferens

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10
Q

Epididymis

A

Metabolically active

sperm cells mature

Divide into three regions: head, body, tail

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11
Q

Physiologic changes in spermatozoa as they transverse the tubular tract

A

Gain the ability for progressive motility

acrosome matures: tightens onto head - gets rid of excess membrane

Plasma membrane - stiffens in some areas and increases flexibility in others

All are testosterone-dependent

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12
Q

Blood-testis Barrier

A

Tight junctions between sertoli cells divide the tubules into two compartments

Basal Compartment: contains spermatogonium and preleptotene spermatocytes

Adluminal Compartment: Comminicates with lumen and contains more advanced stages

Wide range of permeability: complete exclusion of antibodies, free transfer of androgen-binding protein and inhibin

Keeps haploid cells form initiating immune response

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13
Q

Scrotum

A

Testes of many mammals descend into an extra-abdominal scrotum

Reptiles and birds do NOT have scrotums

Some mammals have intra-abdominal testes: elephants, dolphins, whales, armadillos

Some scrotum are non-pendulous: pigs, horses, cats

Some scrotum are pendulous: Dog, cattle, sheep, primates

Testicles within a scrotum are 4-7C cooler than the deep body temperature

Elevation of testicular temperature is an important cause of abnormal spermatogenesis

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14
Q

Tunica Dartos

A

smooth muscle just below the scrotal skin

helps regulate testicular temperature

CONTRACTION: reduces surface area available for heat loss

RELAXATION: increases surface area for heat loss

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15
Q

Cremaster muscle

A

retracts the testicles on cold days

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16
Q

Pampiniform plexus

A

counter current exchange of heat between testicular artery and vein

Decreases temp of blood arrive at testicle by aboutn 5C

17
Q

Puberty

A

The onset is controlled by the maturing hypothalamic-pituitary-gonad axis

in the bull, defined as the age whe an ejaculate has a minimum of 50 million sperm cells with at least 10% motility (far below level acceptable for breeding)

Sperm cells released near puberty have many of the same defects as sperm form degenerating testicles

18
Q

Distrubances of spermatogenesis

A

Reduced sperm production

Increased sperm abnormalities

19
Q

Testicular degeneration

A
  1. Temporary, followed by regeneration
  2. Permanent, with fibrosis
20
Q

Pathogenesis of abnormal sperm production

Stress

A

pain, hunger, cold

21
Q

Pathogenesis of abnormal sperm production

Heat

A

Obesity, scrotal abnormality, climate, fever

22
Q

Pathogenesis of abnormal sperm production

Season

A

photoperiod, nutrition, temperature

23
Q

Pathogenesis of abnormal sperm production

Heredity

A

sperm defects, testis size

24
Q

Pathogenesis of abnormal sperm production

Puberty

A

resembles disturbed spermatogenesis

25
Q

Pathogenesis of abnormal sperm production

Toxicity

A

Plant, bacterial, or environmental toxins

26
Q

Pathogenesis of abnormal sperm production

Nutritional

A

protein, vitamin-A, Se-deficiency

27
Q

Subfertility

increased body temp

A

cuased by excess fat in scrotum

High temperature + high humidity

Fever

Theriogenology VCS862 (13 decks)

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