Male Reproductive Physiology Flashcards Preview

Repro Exam 2 > Male Reproductive Physiology > Flashcards

Flashcards in Male Reproductive Physiology Deck (46):

What do the testes consist of?

1. seminiferous tubules, where sperm are made
2. interstitial tissue, between the tubules
3. sperm transport duct system


What are the seminiferous tubules?

convoluted, hollow, fluid filled tubes that open at both ends and empty into the rete testis


What types of cells are in the seminiferous tubules?

sertoli cells
germ cells


What is on the basement membrane and lumen of the seminiferous epithelium?

basement membrane = spermatogonia (least differentiated)

lumen = spermatids (most differentiated)


What is the function of Sertoli cells?

serve to nurture the developing germ cells

(extend from basement membrane to the lumen and surround the germ cells)


Spermatogenesis consists of what?

1. cellular proliferation by repeated mitotic division
2. entry into meiosis with chromosome duplication, genetic recombination, and meiotic reduction divisions to give haploid spermatids
3. terminal differentiation of spermatids to spermatozoa


Proliferation, meiosis, and differentiation are associated with which intermediate cell types?

proliferation = spermatogonia
meiosis = spermatocytes
differentiation = spermatids


How do type A spermatogonia turn into type B spermatogonia

after going through several mitotic divisions


Spermatogenic cycle

when spermatogonia clones enter meiosis, resting spermatogonia on basement membrane signaled to mitotically divide and new clones push previous clone closer to lumen


What happens in meiosis of spermatocytes?

Meiosis 1 - primary spermatocytes (2N4C) turn into secondary spermatocytes (1N2C)

Meiosis 2 - secondary spermatocytes (1N2C) are turned into spermatids (1N)


What happens in spermiogenesis?

long phase of terminal differentiation where the newly formed haploid round spermatid undergoes dramatic cellular changes to form the spermatozoa


Name some steps in spermiogenesis

-nucleus elongates and chromatin condenses
-Golgi apparatus produces small granules that coalesce to form acrosome
-pair of centrioles migrate to nucleus and bind to it
-axoneme elongates to form the core of the tail
-spermatid loses large amounts of cytoplasm to form the residual body


What is spermiation?

release of spermatid from its tether

(released cell is now a spermatozoa)


What is the function of apoptosis in spermatogenesis?

-keep number of germ cells to a level the Sertoli cells can support
-removal of defective sperm at quality check points


What are the functions of the Sertoli cells?

1. organize clones of germ cells in seminiferous epithelium, support the cells, and ensure their timely release
2. secrete controlling factors that regulate germ cell differentiation and maturation
3. phagocytose degenerating cells
4. produce androgen-binding protein that traps androgens for local and downstream use
5. form tight junctions that form the blood-testis barrier
6. major source of estrogen


What is the purpose of LH and FSH in males?

LH - acts on Leydig cells to increase testosterone secretion

FSH - acts on Sertoli cells and stimulates them in their supporting role, promotes seminiferous tubule growth, and androgen-binding protein production


Why is testosterone important for spermatogenesis?

testosterone helps maintain binding of Sertoli cells to developing sperm cell stages


What is the blood-testis barrier?

formed by tight junctions between adjacent SErtoli cells, divide the seminiferous epithelium into basal and adluminal compartments


What is the purpose of the blood-testis barrier?

to maintain fluid differences and provide immune compartmentalization


Why is there testicular temperature control?

reduced temperature is required for normal spermatogenesis


What are the effects of elevated temperature on spermatogenesis?

-spermatocytes and early round spermatids are very sensitive to heat, become dysfunctional
-Sertoli cells become dysfunctional


What are the 3 main regions of a spermatozoa?

1. head
2. mid piece
3. principal piece


What is the spermatozoa head made of?



What is the spermatozoa nucleus made of?

haploid DNA that is tightly condensed


What is the spermatozoa acrosome made of?

-derived from Golgi
-forms a cap over the apical 1/2 of nucleus
-contains complex array of proteins and enzymes


What is the equatorial segment?

an area where the caudal part of the acrosome thins


What are the 4 sections of the tail?

1. connecting piece
2. middle piece
3. principal piece
4. end piece


What are the major structural components of the tail?

outer dense fibers
mitochondrial sheath
fibrous sheath
plasma membrane


What is the axoeneme made of?

microtubules in the classic "9+2" array, runs down the center of the entire tail


What is the mitochondrial sheath?

confined to the middle piece, the mitochondria are helically arranged around the outer dense fibers


What is the fibrous sheath?

extends the length of the principal piece and starts at the end of the mitochondrial sheath


What is the end piece?

occurs after the fibrous sheath and consists only of the tapering axoneme covered by plasma membrane


What is the sperm plasma membrane?

covers the entire sperm and is vital for normal sperm physiology and the events of fertilization


Explain the path of sperm transport

seminiferous tubule - rete testis - efferent ducts - proximal epididymis


What is the epididymis?

highly coiled structure that connects the efferent ducts to the vas deferens


What is the function of the epididymis?

transport, protect, sustain, mature, and store spermatozoa


Describe the different segments of the epididymis

initial segment = fluid resorption
middle segment = sperm maturation
terminal segment = sperm storage


What is sperm maturation?

when sperm gain fertility


Name some changes that occur in the sperm during transport

-acquisition of the potential for progressive motility
-change in cell surface electrical charge
-major alteration of plasma membrane lipid structure
-movement of the cytoplasmic droplet from the neck to the distal part of the midpiece


Why can't sperm be stored in the epididymis indefinitely?

aging sperm undergo degeneration


How is sperm quiescence maintained during storage?

1. low sodium content in the bathing fluid
2. high sperm concentration
3. secretion of viscous mucoprotein
4. secretion of cell permeating acids that diffuse into cells to keep pH low


What happens if activation of sperm occurs too early?

-incapable of reaching the site of fertilization
-incapable of fertilizing the egg


What are decapacitation factors?

proteins secreted by the epididymis that coat sperm membranes and stabilize them


What is the vas deferens?

an extension of the epididymis that runs from the cauda of the epididymis to the pelvic urethra


What are accessory sex glands?

supply the bulk of fluid in the ejaculate (seminal plasma)

seminal vesicle
bulbourethral gland


What are the functions of the accessory gland fluids?

1. activation of sperm motility
2. buffering capacity
3. nutrient supply
4. stimulate uterine contractions
5. clean the urethra
6. plug the cervix
7. decapacitating factors