Spermatogenesis

Question 1

Know how GnRH, LH, and FSH work together to cause spermatogenesis (including the cell types that secrete the, the cell types that have receptors for them and where feedback occurs).

Answer 1

-GnRH: Secreted from tonic center, Target the gonadotropic cells in the anterior pituitary, Feedback occurs in Hypothalamus
-LH: Secreted from the anterior pituitary, Acts on Leydig cells in the testes, Feedback occurs in Anterior lobe and Hypothalamus
-FSH: Secreted from the anterior lobe, Acts on sertoli cells, Feedback occurs in Anterior pituitary and Hypothalamus

Question 2

GnRH

Answer 2

-Frequent, intermittent bursts: Lasts a couple of minutes
-Cause release of LH: Lasts 10-20 mins, Occurs 4-8 times a day

Question 3

FSH

Answer 3

-Lower concentrations & longer durations: Constant secretion of inhibin and Longer half-life of FSH
-Received by Leydig cells: Progesterone is synthesized (Most is converted to testosterone)

Question 4

LH

Answer 4

-Prevents Leydig cells from becoming unresponsive (reduced receptors)
~low testosterone levels occur
~LH pulses cannot be too long: Excess of testosterone, Intense negative feedback, Reduced testosterone (in long run)
-Too much testosterone
~FSH reduction: From negative feedback
~Sertoli cell function compromised

Question 5

Know the different forms of the male germ cell.

Answer 5

-Spermatogonia
-Primary Spermatocytes
-Secondary Spermatocytes
-Spermatids
-Spermatozoa

Question 6

Spermatogonia

Answer 6

-A1-A4, I, & B
-Specialized diploid cells
-Can revert back to less mature space
-Basal seminiferous epithelium

Question 7

Primary Spermatocytes

Answer 7

-Haploid cells
-Adluminal seminiferous epithelium

Question 8

Secondary Spermatocytes

Answer 8

-Haploid cells: “Crossed Over” chromosomes
-Adluminal seminiferous epithelium

Question 9

Spermatids

Answer 9

-Haploid
-Spherical
-Adluminal compartment

Question 10

Spermatozoa

Answer 10

-Highly condensed nucleus
-Acrosome is formed
-Motility achieved: Development of a flagellum and development of mitochondrial helix
-Lumen

Question 11

What are between cytoplasmic bridges?

Answer 11

Daughter cells

Question 12

Know how the divisions of Spermatogenesis progress.

Answer 12

-Spermatocytogenesis: Mitosis, A1-A4, I, & B Spermatogonia, Stem cells left over, and Last division produces Primary Spermatocytes
-First Meiosis: Produces Secondary Spermatocytes
-Second Meiosis: Produces Round Spermatids
-Spermiogenesis: Transformation into sperm-like shape (Golgi phase, Cap phase, Acrosomal phase, and Maturation phase)
-Spermiation: Separation of formed Spermatozoa from seminiferous epithelium

Question 13

What is the order of the maturation phases of sperm development.

Answer 13

-Golgi
-Cap
-Acrosomal
-Maturation

Question 14

Golgi phase

Answer 14

-Development of acrosome
-Migration of centrioles

Question 15

Cap phase

Answer 15

-Acrosome development continues
-Flagellum elongates

Question 16

Acrosomal phase

Answer 16

-Acrosome development finishes
-Manchette development: Series of microtubules, Associated with nuclear elongation
-Elongation progression

Question 17

Maturation phase

Answer 17

-Manchette disappears
-Mitochondria migrate
-Dense fibers form

Question 18

Spermatogenesis

Answer 18

The whole process of sperm production

Question 19

Spermiogenesis

Answer 19

Differentiation of Spermatids

Question 20

Spermiation

Answer 20

Separation of formed Spermatozoa from seminiferous epithelium

Question 21

Know why stem cell renewal is important.

Answer 21

-Stem cell renewal
-Replenish testis: Injury, Trauma, and High heat
-Keep Spermatogenesis going indefinitely

Question 22

Stem cell renewal

Answer 22

-process of renewing early mitotic cells to always have cells that are dividing to produce sperm.
-A2, A3, A4: Can revert back to less mature space, Can be maintained as a stem cell (Produce more sperm)

Question 23

Stage of spermatogenesis

Answer 23

-Designation applied to a given cross section of a seminiferous tubule.
-Each seminiferous tubule can be at a different stage in any given cross section.
-Based on the degree of maturation of the cells closest to the lumen.

Question 24

Cycle of spermatogenesis

Answer 24

-Time it takes the same cross section to complete all established stages
-Species dependent
-Multiple cycles needed for the whole development process
-All about TIME.

Question 25

Wave of spermatogenesis

Answer 25

-Spermiation only occurs at certain sites. -During a wave seminiferous epithelium progresses through stages. -Causes spermiation to occur at different sites along the seminiferous tubule: creates a wave of sperm cell release. -Provides a relatively constant rate of spermatozoa to the epididymis. -Distance between the same stage is a wave. -Think DISTANCE.

Question 26

Know relative cycle length and duration of spermatogenesis for the boar, bull, and stallion.

Answer 26

Boar ~Cycle: 8.3 days ~Spermatogenesis: 39 days Bull: ~Cycle: 13.5 days ~Spermatogenesis: 61 days Stallion: ~Cycle: 12.2 days ~Spermatogenesis: 57 days

Question 27

Know relative cycle length and duration of spermatogenesis for the ram and man.

Answer 27

Ram: ~Cycle: 10.4 days ~Spermatogenesis: 47 days Human: ~Cycle:16 days ~Spermatogenesis: 75 days

Question 28

Know what factors cause variation in sperm production.

Answer 28

-Testis size -Efficiency of spermatogenesis: Mitotic division and Degeneration of germ cells -Length of spermatogenesis

Question 29

Know how many germ cells are present in the sertoli cells of stallions.

Answer 29

-Primary spermatocytes: 3.0 +/- 0.2 -Round spermatids: 10.9 +/- 0.9 -Max. Potential spermatids: 64

Question 30

Know how many germ cells are present in the sertoli cells of bulls.

Answer 30

-Primary spermatocytes: 1.2 +/- 0.1 -Round spermatids: 5.2 +/- 0.6 -Max potential spermatids: 64

Question 31

Know how many germ cells are present in the sertoli cells of men.

Answer 31

-Primary spermatocytes: 1.3 +/- 0.1 -Round spermatids: 4.2 +/- 0.2 -Max potential spermatids: 16

Question 32

Know what factors might increase apoptosis.

Answer 32

-Normal: Typical part of spermatogenesis -Abnormal: ~Seasonal factors ~Disease ~Trauma ~Heat ~Hormone levels ~Age