ANSC 333 exam 3

Tonic center of the hypothalamus; every 4-6 hours

Where does GnRH come from within the brain in males? What is the frequency of the pulses?

Testosterone

When looking at LH, there is a corresponding pulse of what other hormone?

Leydig cells (interstitial cells)

Where is testosterone synthesized?

He does not because he lacks the testosterone

Would a castrated male still have the sexual behavior/secondary male characteristics? Why or why not?

Sertoli cells

In males FSH acts on which cells?

aromatase

Leydig cells produce small quantities of ________ resulting in small qualities of estradiol to be in circulation.

estradiol and dihydrotestosterone

Testosterone can be transported into sertoli cells, which can convert it to ________ or _________, which is a "more potent version."

Inhibin; because without FSH, spermatogenesis would fail

Sertoli cells will make ______, which has negative feedback to suppress FSH secretions. However, we still get minimal FSH secretions. Why?

constant and continuous

What is a good way to describe the pattern of male hormone production?

Testosterone, Estradiol, Dihydrotestosterone

What 3 hormones are released from the testes and all have negative feedback effects on GnRH production?

Every hormone is metabolized and broken down to be utilized. Once testosterone is utilized, its levels result in going down. The body recognizes it needs to increase the levels again. This creates a new wave of testosterone. Testosterone inhibits GnRH, therefore once testosterone is low, GnRH pulses, releasing LH, and pulsing Testosterone.

Describe why there is pulsation of testosterone within the male body.

GnRH, LH, FSH, Testosterone, Inhibin, Estradiol, and Dihydrotestosterone.

What are the 7 male hormones produced?

Testes

Where are all germ cells/gametes produced?

Proliferation, meiosis, differentiation

What are the 3 different stages of spermatogenesis?

Proliferation

Which stage of spermatogenesis are cells undergoing mitotic replication, even though they are gametes? A1 ends up being 32B spermatogonia.

Sperm Cell Renewal

spermatogonia stem cells can only choose to be a sperm cell. One or some of these cells which have already begun division can start over and "revert" back to become an A1 spermatogonia again.

61 days

In the bull, to get from A1 to end/release of the sperm, how many days is the process?

Meiosis

Which process involves the 32B spermatogonia entering splitting their DNA chromosomes ending with 256 sperm? Transforms from spermatogonia to spermatocyte (primary to secondary).

crossing over

Why are all sperm unique and not clones?

Differentiation

Which stage of spermatogenesis involves the cell making "decisions" to obtain functional competence? This happens in every cell in the body. Transforms from spermatocyte to spermatid.

Golgi Phase, Cap Phase, Acrosomal Phase, Maturation Phase

What are the 4 stages of differentiation?

Golgi phase

Which phase of sperm differentiation involves the golgi apparatus creating an acrosomic granule on top of the nucleus. (becomes the tail).

cap phase

Which phase of differentiation in spermatogenesis puts a cap on the nucleus? Centrioles form the axon to ultimately be the tail.

acrosomal phase

Which phase of differentiation involves the shape of the nucleus changing from a large and round shape to gain functionality. Male is producing ejaculate. Condensation is the packaging of contents as small as possible, all the mitochondria are just below the neck, and provide the energy.

maturation phase

Which phase of differentiation involves the head, neck, middle piece, and the "Principle Piece." The rest of the cytoplasm is removed from cell cytoplasmic drop (contains the Golgi, ER, etc). There is a fully functional tail

Hook-shaped head of sperm

What is unique about the rooster sperm?

basal compartment

Where does proliferation take place? (mitosis)

Continual release of mature spermatids, and an always ready supply available

Seminiferous tubules have different cells at different point for maturation. This allows what?

Spermiation

the release of mature spermatids into the seminiferous tubules from within the sertoli cells prior to their passage into the epididymis.

4.5 cycles * 13.5 days per cycle = 61 days for complete spermatogenesis

How is the spermatogenesis cycle time for cattle calculated to equal 61 days?

to make sure the male is suitable for breeding

What is the purpose of a Breeding Soundness Exam?

60 days; to allow complete spermatogenesis to check viability of new sperm.

How long should you wait between BSE exams? Why?

Apoptosis

What happens to sperm not ejaculated?

measuring tape

How is scrotal circumference measured in species with pendulous penises? (Bulls, Rams)

there is likely lower fertility

With a low number of sperm, one can also infer what?

She will reach puberty later and her fertility will possibly be lower as well

Smaller scrotal circumference can imply what about a sires daughter?

Test at a later date; 60 days later to see a new population of sperm

If an animal has illness or an influx of immune cells at the time of their BSE what happens?

DNA is stored in the head as well as the acrosome. Acrosomes that do not function will cause trouble with fertilization since the sperm cannot penetrate the zona pellucida of the female oocyte.

Why are head abnormalities of sperm an issue?

Crater, Tapered, Ruffled, Knobbed

What are 4 main sperm head abnormalities?

Coiled, Double Mid-Piece, Folded, Detached

What are 4 main sperm tail abnormalities?

the DNA may be okay but without motility (progressive and forward motion), there is no point. If a sample has 0 movement, the collection was either done incorrectly or all the sperm are dead. Sperm also may be subject to temperature shock or it is a defect of the accessory sex glands.

Why are tail abnormalities of sperm an issue?

The dairy industry wants predominantly female offspring, therefore select sperm for x chromosome, and a club lamb facility males are making the profits so a y chromosome is desired.

Why would you need to sort spermatozoa for x or y chromosome DNA?

True

T/F: Semen contains predominantly x chromosomes. X chromosomes are heavier in weight/density.

Staining; with the use of light-activated vital dyes, you will detect x chromosomes. This is because they are more dense than y chromosomes causing them to use more dye and have a higher excitation level than y chromosomes. Dye is taken up only by living cells, however some dyes are used to detect dead cells. Excitation with a laser gives X a charge and Y receives the other charge (+ and -). Magnetism used to attract/repel a specific charge, thus separating the x, y, and dead sperm cells.

What method is used to detect if there is an x or y chromosome in a sperm cell?

search for sexual partner (libido)

courtship (vocalization, kicking, head contact, etc).

sexual arousal

achieve erection

penile protrusion

What are the traits a male should express in pre-copulatory reproductive behavior?

mounting

intromission

ejaculation

What copulatory reproductive behavior should a male express?

dismount

refractory period (male is incapable of achieving an erection/ejaculation)

memory (want the memory to be pleasant for him to establish willingness)

What post-copulatory reproductive behavior should a male express?

HUMAN ERROR; AV too hot or cold, lack of pressure or too much pressure, an audience is present, etc.

What could cause a male's memory to be unpleasant during mating?

They seek their own mates therefore search more

What female animal activity increases during estrus?

Dairy industry; pedometers can measure the steps their females take.

What industry is tracking female activity during estrus?

Menses and Ovulation

At what times does the activity in women (people only) increase?

visual (winking, flagging)

olfactory (pharamones, flehman)

auditory (most auditory is goats)

tactile (kicking by goats)

When talking about reproductive behavior, we are referring to the senses. Give an example of each category of senses used.

Goat Rams

Which species is the most vocal and tactile when interacting with females?

Checking for the position of lordosis (standing/willingness to breed)

Why do goats kick their females?

Males put their nose in the females stream of urine which uses the Vomeronasal organ, to detect if estrus pheromones present or absent.

What is the Flehman response?

This increases the amount of sperm present in their next ejaculation. The idea of competition is stimulating the epididymis to release more sperm. It is important the male be focused during mating.

Why will males watch other males mate?

The safety of handlers and for males to be stronger and faster in their copulation to save time.

Why is the males "focus" during mating important?

Rams; flaccid to flaccid in a matter of seconds.

Which species has the shortest copulation time?

False! Both vascular and fibroelastic penises require blood flow for erection

T/F: Only vascular penises require a large amount of blood flow to achieve erections.

50 mm Hg

What cavernous arterial pressure is considered to be a flaccid penis?

The male recieves a stimulus in the brain which acts on NANC neurons. NANC neurons release nitric oxide in response to the stimulus. The nitric oxide acts on epithelial cells. This causes is an increase in blood pressure within the cavernous and bulourethral arteries in the penis. The increase in blood pressure is due to vasodilation which is where the artery increases in diameter causing an increase in blood flow, which raises the blood pressure. The bulbospongiosus muscle and ishiocavernosus muscle clamp down on the veins to stop the outflow of blood. This means blood comes in through the arteries but does not leave, making blood pressure skyrocket, resulting in the erection.

Describe how the male achieves erection.

bulbospongiosus muscle and ishiocavernosus muscle contract and move the sperm rapidly and forcefully through the urethra. Once ejaculation occurs, male undergoes the refractory period where all muscles relax and blood flow rushes out of the penis to become flaccid again.

Describe the process of ejaculation:

1. Nitric oxide converts GTP to cGMP. cGMP relaxes the sinusoid smooth muscle.

2. Or PDE5 converts cGMP back to GMP to end the erection.

How is vasodilation (to achieve erection) achieved? 2 ways

By blocking PDE5. This prevents the conversion of cGMP back to GTP. This inhibits the return back to a flaccid penis.

How does viagra work in order to maintain an erection?

Sperm travel to the epididymis via the seminiferous tubules from the testes. In the epididymis, the sperm cells mix with the accessory sex fluids. Oxytocin is released from the posterior pituitary as a response to stimuli (visual, bulls watching others etc). Oxytocin binds to the smooth muscles in the vas deferens, causing sperm and accessory sex fluids to move up. Nerves in the glans penis sense their surrounding temperature and pressure. When a warm and pressurized environment is reached, this stimulates the muscles to expel the sperm through the penis.

Before the ejaculation, where are sperm? What causes ejaculation?

If a male has familiar females in a new location, the male will increase his mounting/breeding. This could be caused by the idea or fear of a new male possibly being present. His aggression increases, therefore he mates his females to prevent them being bred by another male.

If a male is in a familiar environment with new females, he will still mate more. His job is the spread his own genetics and every opportunity is taken due to uncertainty of when the females will leave.

If a male is subject to change in environment or females, describe how his breeding behavior will be altered.

1. change in environment

3. change in females

temperature and pressure

What factors can affect a males willingness to be mated via AV?

females

Which gender makes up a majority of production breeding herds?

< 10%

On average, what percentage of a breeding herd do males account for?

at least 2

How many males are needed to have a successful breeding herd?

87.5%

Over the last 3 generations, the ram is responsible for roughly what percentage of the genetic influence within a flock?

1. produce sperm supply via spermatogenesis

2. Detect females in estrus

3. Inseminate and fertilize the female gamete

What are the roles of a breeding male?

False! This is because the BSE does not account for willingness to breed/libido.

T/F: The BSE guarantees fertility.

recognize/examine breeding behaviors

What do most vets fail to do when evaluating breeding males?

electroejaculator

The vast majority of BSEs are preformed with what collection tool?

False, not always

T/F: Every male is stimulated with electroejaculators

feet, leg, eyes

What is examined in the physical portion of a breeding soundness exam?

Rambouillet

Which breed of sheep struggles with sight in regards to breeding soundness?

STDs

Accessory sex glands not functioning can be a sign of what problem?

If a prepuce is long it can be dangerous. They are prone to bacterial infections from the ground, trapping dirt, and subject to being stepped on by surrounding animals or the male himself. Trauma from rough terrain is also cause for concern. Prepuce prolapse will bring bacteria into the sheath, creating a warm and moist environment for bacteria to thrive. During copulation bacteria can be transmitted to the female.

What issues could be a result of a loose prepuce?

Epididymis inflammation, which is detected by palpation.

What can be detected when examining the scrotum in a BSE?

True; servicing capacity is the males ability to breed a large number of females

T/F: The bigger the testicles the higher his servicing capacity

amount of sperm producing tissue

repeatable breeding

heritable; more likely to have sons with larger testicles and can maintain the herd

sperm quality

pubescent age of offspring

what factors give importance to scrotal circumference?

if you have small testicles, you are more likely to also have sperm defects. There are genetics involved in testicular development. Therefore, scrotal circumference has become a factor in selection criteria. It is inferred if a male cannot develop larger testicles, he is incapable of producing quality sperm.

How is testicular size related to semen quality?

A bull with larger testicles will have a female offspring that reaches puberty sooner than a calf sired by a bull with smaller testicles. Heifers calf by 2 years of age. Bull selection is important for this goal being reached. This also matters in males, however females are necessary for herd growth so they're the focus.

How is scrotal circumference of a bull and indicator for the pubescent ages of his offspring?

False, this is a fault of BSEs

T/F: Libido and drive of a male is determinable by BSE and scrotal circumference.

the shorter the spermatic cord, the closer the testicles are to the body permanently. This causes heat stress, disrupts the thermoregulation of the testes and causes sperm death.

Why would a short spermatic cord be an issue?

Sperm must bind to the zona pellucida, bind to the plasma membrane, and the cortical reaction stops others from binding. If a sperm has a crater head defect, it can still bind to the plasma membrane and cause the cortical reaction. However, if the sperms DNA is not good, fertilization will not be achieved or the embryo will deteriorate. The ruffled sperm head defect results in a low functional sperm count. If all sperm are ruffled, no sperm can bind, causing no fertilization.

Can sperm with head abnormalities fertilize oocytes?

True

T/F: Tail abnormalities do not allow entrance into the oviduct for fertilization.

cold shock; if the glass slide is at room temperature

What could be the cause for bent tails in terms of mishandling?

Even though the dominant bull is capable of exhibiting breeding behavior and mounting, the females would re-cycle due to no fertilization. This means more females would end up mating with the the lesser dominant bull, at a later time. This results in fewer calves and later births, causing a decrease in calf production value.

If 2 bulls were responsible for breeding a herd, and the dominant bull was infertile, what would happen?

sperm cryopreservation

what is the technical term for preserving sperm for later use via liquid nitrogen?

Bulls

Which species is the most lasting and cooperative in sperm cryopreservation?

Boars

Which species is collected and often extended in order to impregnate multiple females?

egg yolk and milk

What are the 2 main nutrients for extending semen?

True, this results in cell death

T/F: Cells are undergoing respiration. Without sufficient buffer, the pH will be altered.

True

T/F: There is no ejaculate that is sterile.

To the uterus

Failure to include antibiotics will grow bacteria. These bacteria can be transferred where?

This changes the osmolarity of the cell. it enters into the cell wall and causes sperm to push out water. This change allows for the freezing of the cells.

Why is glycerol included in sperm?

50%

Sperm cryopreservation (freezing) on average kills what percentage of sperm within the sample?

Cryoprotectants are toxic, even though they are required to freeze the sperm.

Why is glycerol the only cryoprotectant used for semen?

True

T/F: Once cryopreserved, semen can last in a nitrogen tank for years.

Dairy

Which industry has driven sexing semen?

X chromosome

Which chromosome has a higher weight due to its increased DNA content?

Dye will bind to the DNA of each sperm cell, as it is run single file through a laser machine that adds a charge to the sperm. Once charged, it is run between a set of magnets which will either retract or attract depending on the charge. Dead sperm will not hold a charge. This is a very slow and stressful process, causing AI to be done in low sperm amounts.

Describe the process for sexing semen:

10-15%

Sexed semen decreases the pregnancy rate by ____ to ___ %

35%

What is a "good" pregnancy rate for dairy cows?

25%

What is the pregnancy rate for a dairy cow with sexed semen AI?

You put them in a parlor and determine which to keep. Typically older cows are sold, along with the less genetically superior, to feedlots. However, feedlots prefer steers, therefore you're losing money.

If you have 1000 head of dairy cows, all bred with sexed semen, and all retaining calves, how do you determine which to keep?

Whitetail Deer

What is actually the high income business for sexed semen?

Intro cytoplasmic sperm injection

(ICSI)

What does ICSI stand for?

True. ICSI is used when the sperm is insufficient. Either not motile, cannot bind, etc. All that is needed is quality DNA from the sperm.

T/F: ICSI skips the acrosomal reaction, penetration, etc and DNA is injected into the female oocyte.

use in people, followed by the equine industry

What drove the development of ICSI?

Freezing stallion semen is difficult, and ICSI allows low motility semen to be used and still achieve fertilization.

Why is ICSI used most commonly in equine?

True, live cover is often required

T/F: Certain breed associations for horses do not permit AI and other assisted reproduction method.

cancer, ultra rapid propagation of superior sires, insurance, alternative to cloning

What are the implications for spermatogoneal stem cell transplantation?

Taking stem cells out of the male and transplanting them elsewhere within the body to function.

What is spermatogoneal stem cell transplantation?

For testicular cancer. This is an issue because radiation targets rapidly proliferating cells. This also affects spermatogenesis (mitosis) and causes DNA damage.

Why did people drive/develop spermatogoneal stem cell transplantation? (What is the problem it is addressing)?

Spermatogoneal stem cell transplantation will harvest and isolate some spermatogoneal stem cells when the male is initially diagnosed with testicular cancer. It will be stored via cryopreservation, in liquid nitrogen, until the cancer treatment is completed. During remission, sperm cells will be placed back into the male, and spermatogenesis can continue.

How is spermatogoneal stem cell transplantation solving the problem of radiation being destructive?

It is deemed unethical to expose animals to livestock

Why is spermatogoneal stem cell transplantation not practiced in livestock?

Immediate transport, the cervix, the uterus, the oviduct, fertilization

What are the stages in the cycle from once sperm are transmitted to Fertilization?

retrograde loss

phagocytosis

entrance into cervix/ uterus

what are the components of immediate transport?

"privileged" pathways

removal of non-motile sperm

removal of some abnormalities

what occurs within the cervix once the sperm enter?

Fast transport and then slow transport

Components of ejaculate/copulation stimulates contractions to move sperm up. How does the speed of sperm change during immediate transport?

washing out of sperm

What is retrograde loss?

Boars

Which species releases a gel fraction in order to increase volume and seal off the cervix?

When the female immune system attacks sperm cells

What is phagocytosis?

the cervix

Where do sperm begin to change within the female?

capacitation is initiated. capacitation is the process of sperm gaining their ability to bind. When sperm mix with seminal plasma, protein structures on the sperm become rigid and strong. This is a protectant of the DNA, given that ejaculation is such a rapid and violent process and in order to prevent premature binding so it reaches the oocyte. The sperm head has to bind to the oocyte but early on binding cites are covered up by protein. Enzymes in the uterus and oviduct cleave and break off structural proteins so sperm can bind to oocyte.

Describe what occurs in the uterus/oviduct for capacitation

capacity is completed

hyperactive motility

what occurs within the oviduct?

Acrosome reaction

spermatozoon penetrates the oocyte

male and female pronuclei form

What occurs during fertilization

Because copulation is not sterile. Ideally immune cells target bacteria, but semen is recognized as foreign and become target and subject to phagocytosis.

Why is the number of immune cells higher in the uterus during copulation?

AI bypasses the natural mechanisms when inseminating

Why is AI a problem with sperm count?

because phagocytosis

Why is there such a high sperm count requirement?

sperm gaining the ability to bind to oocyte

what is capacitation?

uterus, horns

99% of the time, sperm are deposited into the ______ , not the ______ because the rod is solid and the uterus is twisted. This prevents trauma.

True

T/F: The site of deposition of sperm during AI does not matter as long as it is beyond the cervix.

True!

T/F: Embryo transfer is more likely to cause extra trauma because you need to get the embryo into the uterine horn.

cervix

Copulation occurs in the vagina. Sperm then have to travel through the _______ .

All mucosal cells are not created equally so not all mucus is secreted in equal amounts. Towards the luminal center, mucosal cells produce sulfomucin, which is a really thick mucus. Since bacteria do not have tails, thus lack locomotive function, they are trapped and caught in the mucus. Sperm which have low motility also get caught in the mucus. In the crypts, sialomucin which is a more watery mucus. Sperm make it through the sulfomucins to sialomucins and make their way up the crypts to the more water watery mucus as a way to conserve energy.

Describe the privilege pathways of the cervix:

Cows were inseminated in their uterine horns and the uterine body, and tested for how much sperm was recovered within the vaginal canal. There was not difference. However, when inseminated deep within the uterine horns and the cervix, more sperm was recovered in the vagina. The explanation is that the cervix flushes out unwanted contents. Therefore, AI must bypass the system in order to guarantee sperm makes it through the uterus.

Describe why AI deposition is beyond the cervix:

Sheep, because their cervix is too difficult to get through. Sheep have laproscopic AI instead.

Which species is transvaginal AI not practiced in and why?

equine

which species is in estrus for up to a full week, thus making ultrasound very important to see the follicle and determine the time of ovulation? In this species, the AI sperm is only a fraction of the amount that would be ejaculated during copulation through live cover.