Since stallions are long day breeders, a stallion's libido may be reduced during the winter months due to the lowered levels of this hormone
What cells in the seminiferous tubules are responsible for growth and development of the spermatid?
sperm maturation takes place in which part of the epididymis
body of the epididymis
sperm production in a single day is great. What is roughly the number of sperm produced by a stallion in a day?
this would be considered an abnormal sperm
What is the average volume of the stallion ejaculate?
what is the term used to describe the recovery time between ejaculations?
a volatile substances produced and released by a mare through urine that can stimulate sexual behavior in a stallion is
when collecting a stallion using an artificial vagina, what is one tactile stimuli necessary for the stallion to ejaculate properly
temperature of water in the water jacket
one behavioral activity for mare in heat would be
if you are using PGF2a to synchronize the estrous cycle of a mare, you must have what structure present on the mare's ovary?
when you intend to simulate a normal CL's function, you would need to provide what hormone to the mare?
what hormone does an injection of hCG mimic or simulate in a mare?
what is the name of an oral progesterone product used to synchronize the estrous cycle of a mare?
what is the optimal length of day light for shortening the spring transition period in a horse?
what is the product name for the implant that contains GnRH?
methods used to regress the CL are not effective during this stage of the estrous cycle
if you wanted to completely synchronize estrus in a group of mares and were using PGF2a, how many injections would you recommend?
the most common and practical method of shortening the transition period is what
cystorelin is a product that contains this hormone
to shorten the anestrus and spring transition for a mare, supplement light should be started in ____ if a February breeding is desired
the total length of the mare's estrous cycle can vary greatly during different times of the year. Which stage of the estrous cycle would likely vary the least in length?
when the light portion of the day is increasing, the release of melatonin from the ____ will ____, causing a(n) _____ in the release of _____ from the hypothalamus
pineal gland - decrease
increase - GnRH
The likely explanation for the first heat in the spring of the year to sometimes not exhibit strong behavioral signs of estrus is that ___ has not been present at high levels and therefore prime the brain for a more intense response to the high levels of ___ just priod to ovulation
the highest blood concentration of melatonin is during what season of the year?
why do we typically see antral follicles increase in size as the mare progresses through the spring transition period
antral follicles increase in size as they fill with more fluid. when there is enough fluid (antral follicles are big enough) they rupture and cause ovulation as the fluid in follicle flushes the egg out
for the female, a true haploid oocyte is not actually formed, however completion of meiosis does occur. What is the event that initiates the completion of meiosis?
normally, mitosis is the first step of oogenesis. What is the main function of mitosis?
increase number of cells
what is one direct effect of progesterone on the reproductive tract of the mare?
decreased myometrial contractions
what original follicular cells does the large luteal cells develop from?
what is the term used when a corpus luteum is degenerating or regressing?
the presumed reproductive status of a mare in the luteal phase is what?
during the luteal phase, mares will have elevated levels of progesterone. a "progesterone block" prevents ovulation. What gland or tissue does the "progesterone block" affect during the luteal phase?
meiosis arrests at birth, but will resume at puberty. What is the trigger for the resumption of meiosis?
what is the hormone that causes the regression of the CL?
What term describes the transformation of the follicular cells to luteal cells?
the synthesis of estrogen requires the binding of a pituitary hormone to a receptor on the cell membrane of the granulosa cell. What is this pituitary hormone?
list two effects that estrogen would have on the reproductive tract of the female during the estrous cycle
increased edema and increased mucus secretion
what is one behavioral change that is caused by high levels of estrogen in the brain of the mare during estrus?
increased physical activity
the production of estrogen is a joint effort between the theca interna cells and the granulosal cells. What hormone is synthesized by the theca interna cells and is converted to estrogen by the granulosa cells?
follicles that do not ovulate will degenerate. What is the term used to describe the degeneration of the follicles on the ovary?
during the development of the dominant ovulatory follicle, levels of ____ will increase in the blood, ultimately reaching a threshold concentration triggering the surge of GnRH from the hypthalamus' surge center
We have talked about two hormones that are produced by cells of the follicle. Both of these hormones can inhibit or slow down the release of FSH from the anterior pituitary by providing negative feedback. What are the names of those hormones?
estrogen and inhibin
ovulation does not occur during the diestrus stage of the estrous cycle because the hypothalamus is unable to release a surge of what?
What would be one cause of the complete absense of estrus?
the dominant structure on the ovary during the follicular phase would be the?
the predominant hormone seen during the follicular phase of the estrous cycle is?
the stage of the estrous cycle that is characterized by having the highest level of progesterone is the?
the average length of an estrous cycle in a mare would be
mare have multiple estrous cycles during certain months of the year. the mare is said to be a ___ breeder
the stage of the estrous cycle when a mare is receptive to the stallion is referred to as?
the term used when describing the first estrus seen in a mare following foaling
the normal length of time for hear to take place in the mare is?
the transitional stage of the estrous cycle that immediately follows the estrus stage is?
for the first ovulation to take place in a filly, her hypothalamus must have a surge of what hormone?
of the colt or filly, which sex normally reaches puberty at the earliest age?
social cues may alter the onset of puberty in females. Prepubescent females, housed in large groups (<10), will often reach puberty at an ___ age compared to a much smaller group of prepubescent females.
the season when a filly is born can have some influence on what age filly reaches puberty. At what age would you expect for a normal filly, born in the spring (april) to reach puberty?
a fundamental difference between a male and female hypothalamus is that the female has two regions in the hypothalamus called the ___ center and the ____ center
defeminizing of the hypothalamus in the male fetus occurs when ___ crosses into the brain and is converted to ____
what compound prevents estrogen from crossing the blood brain barrier in the female fetus?
fillies that are thinly conditioned (low body fat stores) will likely reach puberty ___ as compared to those fillies that are moderately conditioned (adequate body fat stores)
XX embryo exposed to TDF will likely be?
a female that looks like a male
what is the anterior pituitary made from?
embryoinic roof of mouth
what is a cryporcid?
a colt with testicles that have not descended
What do leydig cells produce to instigate the growth of a penis on a colt?
an inguinal hernia is?
when the testicles creep back up through the inguinal ring into the abdominal cavity
where do primordial germ cells move to?
When do the testicles descend?
during 3rd trimester
Where does progesterone come from?
corpus luteum and the placenta
where does FSH come from?
where does estradiol come from?
Female: granulosal cells
males: sertoli cells
where does oxytocin come from?
synthesized in hypthothalamus and luteal cells in the coprus luteum
where does inhibin come from?
Female: granulosal cells
Male: sertoli cells
where does testosterone come from?
where does PGF2a come from?
uterus- uterine endometirum
where does LH come from?
where does equine gonadatropin come from?
where does GnRH come from?
what is the primary function of the leydig cells in the testicle?
what in one function of the bulbourethral gland found in a stallion?
produces pre-ejaculate flush
when evaluating semen of a breeding stallion under a microscope, the presence of proximal cytoplasmic droplets on the tailpieces of the sperm would indicate what?
overuse of breeding stallion
where in the reproductive tract of the stallion would sperm be produced?
the function of the pampiniform plexus is to do what?
modulate testicular temperature
the final semen product ejaculated from a male contains sperm, fluids and nutrients. Collectively, where would the fluids and nutrients originate from?
what is the function of the tail of the epididymis?
stores mature sperm
what is the function of the body of the epididymis?
allows for sperm maturation and transports sperm to tail of epididymis
when the ovum is ovulated it must first enter the ___ which funnels the ovum into the ___.
the vet procedure often performed to prevent fecal contamination of the mare's reproductive tract is referred to as?
what structure commonly suspends the reproductive tract in the abdominal cavity?
the inner-most tubular layer of the reproductive tract is called the ____ layer
the female reproductive tract is highly vascularized. What is one of the vessels providing a route for blood flow away from reproductive tract of the mare?
the cortex region of the mares ovary is located where?
inner-most tissue layer
what is the function of the uterine horn?
guides sperm to egg