Lecture 28 3/22/24

Question 1

What are the endocrine requirements that must be met for sperm production?

Answer 1

-adequate secretion of GnRH from hypothalamus
-FSH and LH secretion from anterior pituitary
-secretion of testosterone and estrogen

Question 2

Which cells produce testosterone?

Answer 2

Leydig cells

Question 3

What is the role of Sertoli cells?

Answer 3

convert testosterone to estradiol

Question 4

How do testosterone and estradiol act on the hypothalmus?

Answer 4

negative feedback on the hypothalamus leads to reduced GnRH production, which reduces LH and FSH production

Question 5

Which type of center is present in the hypothalamus in males, and which is not?

Answer 5

-tonic center IS present
-surge center IS NOT present

Question 6

Why is it important that LH is released in pulses in the male?

Answer 6

-high conc. of testosterone is needed in the seminiferous tubules for spermatogenesis
-Leydig cells can become refractory/reduce secretion of testosterone when exposed to sustained high levels of LH

Question 7

What is puberty in the male?

Answer 7

ability of the male to produce and ejaculate at least 50 mil. sperm with at least 10% motility

Question 8

What are the endocrine hallmarks of male puberty?

Answer 8

-sharp increase in testosterone
-secretion of GnRH, FSH, and LH

Question 9

What pathway do sperm follow from the testis out of the body?

Answer 9

-rete tubules
-efferent ducts
-epididymis
-ductus deferens
-urethra

Question 10

What happens to sperm in the head and body of the epididymis?

Answer 10

changes that allow the sperm to become fertile

Question 11

What is the function of the tail of the epididymis?

Answer 11

storage organ for sperm prior to ejaculation

Question 12

What is seminal plasma?

Answer 12

mixture of spermatozoa with fluids from the accessory sex glands

Question 13

How does a normal testis appear on ultrasound?

Answer 13

hypoechoic homogenous oval structure

Question 14

What are the phases of spermatogenesis?

Answer 14

-proliferation
-meiotic phase
-differentiation

Question 15

What is the proliferation phase?

Answer 15

phase in which the spermatogonia undergo mitotic divisions

Question 16

What is the meiotic phase?

Answer 16

phase in which the spermatogonia undergo meiotic division to form spermatocytes/spermatids

Question 17

What is the differentiation phase/spermiogenesis?

Answer 17

-no divisions occur
-spermatid undergoes transformation to become a fully differentiated and specialized sperm cell

Question 18

What phases occur within the differentiation phase?

Answer 18

-Golgi phase
-cap phase
-acrosomal phase
-maturation phase

Question 19

What happens during the Golgi phase?

Answer 19

highly-developed Golgi apparatus gives rise to the acrosome

Question 20

What happens during the cap phase?

Answer 20

-acrosome forms a distinct cap over anterior portion of nucleus
-primitive flagellum forms

Question 21

What happens during the acrosomal phase?

Answer 21

-acrosome continues to spread and cover more of anterior nucleus
-nucleus begins to elongate and shift to one aspect of cell
-spermatids become deeply embedded in Sertoli cells

Question 22

What happens during the maturation phase?

Answer 22

-final assembly to form spermatozoon
-mitochondria cluster around flagellum in a spiral fashion

Question 23

What is spermiation?

Answer 23

process by which mature spermatids are released from the Sertoli cells into the lumen of the seminiferous tubules

Question 24

Which features are seen in mature sperm?

Answer 24

-head with acrosome and nucleus
-neck that joins head to mid-piece filled with mitochondria
-tail containing flagellum

Question 25

What are the components of the testis parenchyma?

Answer 25

-seminiferous tubules -interstitial space containing vessels, connective tissue, lymphatics, nerves, and Leydig cells

Question 26

What are the two major regions of the seminiferous tubules?

Answer 26

-basal compartment -adluminal compartment

Question 27

What occurs in the basal compartment of the seminiferous tubules?

Answer 27

spermatogonium divide to form other spermatogonia and primary spermatocytes

Question 28

What occurs in the deep adluminal compartment of the seminiferous tubules?

Answer 28

primary spermatocytes divide into secondary spermatocytes and spherical spermatids

Question 29

What type of sperm are in the peripheral adluminal compartment of the seminiferous tubules?

Answer 29

sperm cells that are near complete maturation but still in contact with Sertoli cells

Question 30

Why is it important that there is a counter current between the testicular artery and vein?

Answer 30

allows for some testosterone to be recycled in order to maintain high local concentrations in the testes

Question 31

Which hormones are produced by Sertoli cells?

Answer 31

-estradiol (converted testosterone) -inhibin

Question 32

What determines the number of sperm cells that a testis can produce?

Answer 32

-number of Sertoli cells -size of the testis

Question 33

What is the blood-testis barrier?

Answer 33

tight junction of Sertoli cells with the basement membrane that prevents immune attack of the sperm cells

Question 34

How do sperm motility and fertility change throughout the epididymis?

Answer 34

-sperm are non-motile when in the head -sperm have some motility and fertility in the body -sperm are motile and fertile once they reach the tail

Question 35

What are the characteristics of the ampulla?

Answer 35

-enlargement of ductus deferens -serves as sperm reservoir

Question 36

What is the main characteristic of the seminal vesicle/vesicular gland?

Answer 36

produces the majority of the ejaculate

Question 37

What is produced by the bulbourethral gland?

Answer 37

gel fraction of the ejaculate

Question 38

What is produced by the prostate gland?

Answer 38

sugars and proteolytic enzymes

Question 39

What are the functions of the seminal plasma?

Answer 39

-vehicle, protection, and energy for sperm -capacitation -effects on female repro tract

Question 40

What are the characteristics of the spermatic cord?

Answer 40

-suspends testis in scrotum -provides pathway to and from the body for testicular vasculature/lymphatics/nerves -houses ductus deferens, cremaster muscle, and pampiniform plexus

Question 41

What is the function of the pampiniform plexus?

Answer 41

transfer heat from the arterial blood into he venous blood so that the blood reaching the testes is optimal temp.

Question 42

What is the tunica dartos?

Answer 42

smooth muscle in the scrotum that responds to temp. changes to move the testes closer to or away from the body

Question 43

Why is it important that the scrotum is heavily populated with sweat glands?

Answer 43

allows for thermoregulation and cooling of the testes via evaporative heat transfer

Question 44

What is evaluated in a sperm analysis?

Answer 44

-sperm producing ability of the testis -number of morphological normal sperm -number of motile sperm -viability of sperm

Question 45

Why is an artificial vagina used to collect sperm?

Answer 45

provides appropriate temp. and pressure stimuli

Question 46

What are the main parameters evaluated in semen collection?

Answer 46

-total vol. in mLs -conc. of sperm/mL -total number of sperm

Question 47

How is sperm motility assessed?

Answer 47

% of sperm that move in forward direction; count out of 50 sperm and estimate

Question 48

What percent of sperm must be morphologically abnormal to cause reduced fertility?

Answer 48

20% or greater

Question 49

How is the number of insemination doses per ejaculate determined?

Answer 49

number of morphologically normal and progressively motile sperm/number of sperm wanted per dose