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ACBS Reproductive > Spermatogenesis > Flashcards

Spermatogenesis Flashcards

1
Q

3 Phases of Spermatogenesis

A

Proliferation: Mitotic divisions of spermatagonia
Meiosis: Meiotic Divisions resulting in haploid spermatids
Differentiation: Morphological transformation of spermatids into spermatozoa

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2
Q

Endocrine Regulation of Testis Requirements

A

Pulsatile LH and FSH
Pulsatile GnRH
High [ ] of test. in seminif tubules
adequate number of LH receptors in Leydig Cells

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3
Q

Pulsatile GnRH

A

every 3-6 hours
frequent, intermittent episodes lasts for only a few minutes at a time
causes LH and FSH discharge

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4
Q

LH and FSH discharge from GnRH

A

LH: 10-20 minutes and 4-8 times a day
FSH: lower [ ] than LH but longer duration. Is inhibited by inhibin from adult testis (sertoli cells)
lasts 100 minutes?

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5
Q

Sustained Testosterone Secretion in Men

A

Lack of Surge Center
-LH remains consistent
-Episodic pattern
-Steady Pulses of GnRH and LH= steady release of testosterone

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6
Q

High Testosterone in Seminiferous tubules

A

Leydig Cells
- Blood LH elevates about 30-75 minutes
-synthesize and secrete test
-convert P4 to Test

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7
Q

Low Testosterone in Systemic Blood

A

High Testosterone is neccesarry for spermatogenesis
intratesticular testosterone [ ] is 100-500 x greater than systemic
Low test. in systemic prevents down regulation of of GnRH and LH (test has - feedback on GnRH and LH)

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8
Q

LH receptors in Leydig Cells
Importance for testicular function

A

Prevents sustained LH
Sustained LH would decrease LH receptors in Leydig Cells

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9
Q

Leydig Cells

A

Below Basement membrane
LH stimulates P4 production, most of which is converted into testosterone
-pulsatile LH thus important
-testosterone in testis 100-500x greater

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10
Q

Sertoli Cells

A

-Converts Testosterone to Estradiol and a-DHT (- hypothal feedback)
-Androgen Binding Protein
(increases test [ ] in seminif)
Produces inhibin –> FSH suppression
-FSH stims tight junction formation btwn Sertoli cells (FSH dependent)

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11
Q

Goals of Spermatogenesis

A

-Male supplied with continual gametes through stem cell renewal
- Genetic Diversity
-Billions of sperm to maximize repro opportunity
-immuno privileged sites where germ cells not destroyed while developing

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12
Q

Participating Cell Types in Spermatogenesis

A

Spermatagonia (stem cells)
-goes from 2n to 1n and then change shape to become spermatazoa
Sertoli Cells
-support for germ cells
-env’t for maturation
-substances for meiosis
-hormonal signals to control spermatogenesis
-Primary spermatocyte
-Secondary Spermatocyte (spermatid)

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13
Q

Proliferation

A

Stem Cell Renewal (2n)
A, I, and B spermatagonia
Mitotic Division (lots of B)
Intercellular Bridges lost to allow spermatagonia to go back to stem cells
-Basal Compartment
-Maintenance of Stem Cells, keeps spermatogenesis going indefinitely
replenishes stem cells in case of trauma/ high heat

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13
Q

Meiotic Phase

A

Haploid Spermatids (n)
Crossing Over = diversity
each spermatid unique (heterogeneity)

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14
Q

Differentiation Phase

A

Spermatazoan (n)
-Head and Flagellum (middle and principle piece)
- NO further cell division

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15
Q

Where does spermatogenesis take place?

A

Entirely in Seminiferous Tubules

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16
Q

Intercellular Bridges

A

Communication for synchronizing development
spermatagonia, spermatid, and spermatocytes all connected by these bridges

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17
Q

Differentiation (spermiogenesis) phases

A

Golgi Phase
Cap Phase
Acrosomal Phase
Maturation Phase

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18
Q

Golgi Phase

A

Acrosomic Vesicle Formation
centrioles –> axoneme

???
Cap like structure contains enzymes– also central portion of flagellum

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19
Q

Cap Phase

A

Acrosomic Vesicle Spreading over the nucleus
1) acrosomic vesicle spreading over nucleus
2) prim flagellum: DC goes towards seminiferous tubule lumen

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20
Q

Acrosomal Phase

A

nuclear and cytoplasmic elongation
1) acrosome covers 2/3 of nucleus
2) nucleus elongates
3) manchette forms

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21
Q

Maturation

A

Final Assembly that form spermatazoan
-postnuclear cap forms
-formation of middle piece
principle piece forms
-plasma membrane integrity important for survival of sperm
released into lumen

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22
Q

Sperm Head Parts (main)

A

Nucleus, Acrosome, post-nuclear- cap

23
Q

nucleus

A

nuclear condensation
chromatin keratinized
histone replaced by protamines

24
Q

Acrosome

A

contains hyrdolytic enzymes for penetrating corona radiata and ZP

25
Q

Post-nuclear cap

A

lower 1/3 of nucleus
developed from microtubules of manchette

26
Q

Tail Parts

A

Capitulum
Middle Piece
Principal Piece
Terminal Piece

27
Q

Capitulum

A

fits into implantation socket
neck region flexibility

28
Q

Middle Piece

A

(axoneme) covered in mitochondria
9 microtubule doublets
2 central filaments

29
Q

Principle Piece

A

Majority of tail

30
Q

Terminal Piece

A

MIcrotubules only

31
Q

Spermiation

A

release of sperm from Sertoli cells into the lumen of seminiferous tubule

32
Q

Seminiferous cycles

A

-Cellular generations
-stages of cycle
-DUration of one cycle
-How cycles are repeated

33
Q

Spermatogenic wave

A

?? SLide 5 lecture 2

34
Q

spermatogenesis efficiency

A

amount of spermatazoa in semen
2 weeks for adverse effects to prevent
6-10 weeks to full recover sperm amount

35
Q

Sperm motility

A

% sperm swimming in linear fashion
stops moving under 18, measure at 37 c

36
Q

Sperm Temperature

A

Temp dependent
ATP production increases as temp increases
motility increases with temp too

37
Q

sperm metabolism: ATP utilization in sperm

A

-Motility (uses 60%)
-Substrate Cycling (other 40%)
Maintenance of Ionic gradients
-very small amount
Transcrip and Transl
-uses none after nucleus condenses

38
Q

Sperm Head abnormalities

A

originate in testis
faulty differentiation

39
Q

Sperm Tail Abnormalities

A

originate in epididymus
faulty epididymal transit/maturation

40
Q

Extenders in sperm

A

Extend ability of sperm to be further used in fertilization
SHOULD BE:
Isotonic
Buffer
cryoprotectant
Provide nutrients
Antibiotic
Low in Cost

41
Q

Semen Quality Evaluation

A

Ejaculate Volume
General Appearance
Concentration of spermatazoa
% of motile sperm

42
Q

Isotonic

A

hypotonic- cell lysis
hypertonic- dehydration

43
Q

Buffer

A

Prevent changes in PH
tris, citarte, phosphate

44
Q

Cryoprotectant

A

cell penetrating (glyceros+DMSO)
non-penetrating (milk, egg yolk, lipoprotein)

45
Q

Nutrients

A

Glucose and Fructose
spermatazoa have no anabolic activity

45
Q

Flow Cytometry

A

look at end of lecture 14

46
Q

Flehman Response

A

Uses vomeronasal organ to recognize pheromones
turnes lip up to expose teeth on cows

47
Q

Penis Erection Physio

A

-Elevated Arterial blood flow
-Dilation of Corporal Sinusoids
-Elevated Intrapenile pressure
-Relaxation of the retractor penis muscle

48
Q

Viagra

A

Keeps Cyclic GMP levels high
Or inhibits PDE5
No parasnythetic induction of NO ???

49
Q

EJaculation

A

expulsion of semen and spermatazoa
simple neural reflex
-intromission
-glans penis stim
-forceful muscle contraction
Muscles
-urethralis
-ischiocavernosa
-bulbospongiosa

50
Q

steps to expulsion

A

1- intromission
2- glans penis sensory stimulation
3- sudden powerful contraction of the three muscles above
4-semen released

51
Q

sexual prep
increase sperm released

A

false-mounting
restraint

52
Q

Postcopulatory

A

Refractivity and Recovery
-degree of rest prior
-age
-species
-degree of female novelty
-number of previous ejaculates
satiation vs ehaustion

53
Q

Repro behaviors controlled by CNS (central nervous system)

A

relies on estradiol and test.

54
Q

Hypothalamus and testosterone

A

inherently female with surge and tonic center
test crosses blood brain barrier during embryogensis and destroys surge center
testosterone is converted to estradiol via aromatase

55
Q

alpha-fetoprotein

A

produced in ebryonic yolk sac and fetal liver
fetal blood osmotic regulator and carrier of fatty acids
binds with E2 but not test

ACBS Reproductive (9 decks)

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