The expression of estrus by mammalian female is
dependent on elevated serum estrogenan outward sign of impending ovulation
spontaneous ovulators
do not require the mating stimulus to ovulate
Induced ovulators
dependent upon a hormonal and neural stimulus to ovulatebecome pseudopregnant after sterile mating
characteristics of a long estrus cycle
estrus is day 1 of the cyclehave long luteal phase
animals displaying short estrus cycles can form CL
which may or may not be functionalwhich may depend on the secretion of PRL triggered at time of mating
pseudopregnancy serves an important function in the reproduction of a species
that are either induced ovulators or have short estrous cyclesallows time for the embryo to signal its presence so that the CL can be maintained.
the menstrual cycle differs from the estrous cycle in the following ways
ovulation occurs in the middle of the cycleestradiol concentrations in the blood are relatively high during luteal phase
the preovulatory LH surge in mammals
is initiated by a rapid increase in estradiol produced by the granolas cellsis dependent upon estradiol triggering a significant release of GnRH from hypothalamus is terminated when serum E2 decreases
Annie, a promiscuous rat, has encounters with male rats. Which are true?
annie mates josh, a sterile rat, becomes pseudopregnant for 12 dannie mates with mark, a fertile male. 3 days later, Bruce, a strange male, visits annie. She aborts one or 2 days later
the LH surge in chickens occurs at a later time each night because
ovulation occurs later each day making the F1 follicle less mature at the time of the crepuscular peak and less able to increase the LH surge.
List in correct order 1. oviposition, 2. ovulation, 3. crepuscular peak of LH, 4. P4 secretion by F1 follicle is initiated 5. LH surge
3, 4, 5, 1, 2
fertilization of the avian egg occurs in the
infundibulum
the following structural features are characteristics of steroid producing cells
abundant mitochondriaextenive smooth ERabundant lipid droplets
fertilization of the avian egg occurs in the
...
the steroidogenic acute regulatory protein is
localized between the inner and outer mitochondrial membranenecessary for the conversion of cholesterol to pregnenolone
the amount of P4 produced by a luteal cell is influenced by
the amount of cholesterol availablethe number of LH receptors on the luteal cell membranenumber of LDL and HDL receptors on the cell membrane
Aromatase is a key steroidogenic enzyme because
it converts T to E2 it is present in granulosa cells of mammals and responsible for induction of LH surgeit is present in sperm and has a role in fluid regulation in the efferent ductules
serum binding proteins
prevent the rapid clearance of the hormones they bindare produced by the liver
differences between a free and conjugated steroid are
free steroids are the active formfree steroids are generally found in the feces
steroids synthesized in the delta 4 pathways are
progesterone, testosterone
what's correct order of synthesis in these steroids1. estradiol 2. pregnenolone, 3. androstenedione, 4. progesterone, 5. testosterone
2, 4, 3, 5, 1
steroids synthesized in the delta 4 and 5 pathway differ in what ways
more potenthave double bond between C4 and C5
enterohepatic recirculation of steroid
is recycling of steroids between the gut and liverhelps to maintain elevated concentrations of androgens and estrogens in the bloodcan be altered by diet and antibiotics
secondary sites of steroidogenesis
convert an active steroid to another active steroidconvert an active steroid to conjugated steroidare skin, gut, hypothalamus
mrs jones is taking a high dose of tetracycline, a broad spectrum antibiotic and the birth control pill. As a result, the enterohepatic recirculation of estrogen in her body will be
decreased, resulting in decreased blood concentrations of estrogens
the enterohepatic recirculation of steroids can be altered by
reducing or eliminating the bacteria in the gutincreasing the liver enzyme responsible for conjugation of steroidsincreasing movement of food through the intestine
identify the activities which change enterohepatic recirculation of steroids
taking sleeping pillstaking antibioticsbeing exposed to high concentrations of pesticides
a graffian follicle differs from a primary follicle in what ways
largerhas an antrumhas many layers of granolas cellshas theca layers
the granulosa layer in mammals differs from the theca layer in what way
granulosa is a target for FSHgranulosa layer produces primarily estrogen
the 2 cell theory is different between birds and mammals in what way
in birds, the granolas synthesizes P4 and theca synthesizes androgens and estrogensin mammals, the granolas synthesizes estrogens and theca synthesizes P4 and androgens (do not consider the follicle immediately preceding ovulation)
the single cell layer covering the ovary is called
surface epitheliumis proposed to be the site for ovarian cancer
the ovarian follicles are regulated primarily by the pituitary hormones FSH and LH. What is true about these?
FSH receptors are on granulosa cellsLH receptors are present on theca cells and then as the follicle matures, LH receptors are also present on granolas cells
Inhibin and activin, both ovarian hormones, differ in the following ways
inhibin acts on the anterior pituitary gland to decrease FSH secretionaction acts on the ant pituitary to increase FSH secretion
What is the correct order of these functions going from that function which requires the least exposure time to LH to that which requires the longest exposure time to LH?
oocyte formation, ovulation, CL formation
at the level of the ovary, which of the following steroids and steroid receptors are essential for ovulation
P4P4 receptor(NOT estradiol)
The following changes occur as the follicle undergoes morphological and biochemical changes to become a CL
basal lamina between the granulosa and theca layer is broken downnerves and blood vessels invade the granulosa layerthe number of LH receptors on the newly formed luteal cells increasethe amount of the steroidogenic enzyme, 3-beta hydroxysteroid dehydrogenase required for the synthesis of P4 is increased
the uterus is involved in luteolysis in the following species
sheep and cow
You are a vet for a farmer who has a large sow and dairy operation. He wants you to inject his sows and cows with PGF on day 10 of their cycle to synchronize them for breeding. You tell him you will only inject the cows on day 10 because...
The CL of sows on day 10 of their cycle is not responsive to PGFthe CL of cows has adequate PGF receptors on day 10 so the CL is responsive to the luteolytic effects of PGF
luteolysis in the human and non-human primate is primarily caused by
change in the size of the LH receptor so that eventually the LH receptor is not able to signal to the 2nd messenger in the luteal cell
RU-486 can cause abortion because
it binds to the P4 receptor thus preventing the action of P4 in the CL
the endocrine cells in the testis are
leydig cellsprimary spermatocytes, spermatids, and spermsertoli cells
sertoli cells are essential for fertility because
they produce inhibitthey produce the androgen BPare nurse cells supporting the maturation of sperm
Leydig and sertoli cells secrete hormones. What is correct?
leydig cells are the major target for LH which stimulates testosterone secretionsertoli cells are the major target for FSH which causes secretion of inhibin
prolactin has an important role in the over and testis of seasonal reproducers because
PRL receptors are present on luteal cells and stimulate P4 production in rats and micePRL receptors are present on leydig cells of seasonal reproducers (bears and sheep)PRL communicated photoperiodic signals to the testes
The absence of steroudogenic enzyme, 5a-reductase, in young boys results in..
failure of the prostate to developlack of male external genitalia
androgen BP
is produced by sertoli cellsbinds testosterone and maintains very high concentrations of T in the male repro tract
oral contraceptives prevent pregnancy by
preventing ovulationmaintaining relatively low and constant concentrations of FSH and LH in the blood
the transgenic estrogen receptor knockout mouse (ERKO) is infertile because
the mouse is unable to respond to estrogenmovement of ions and water from the efferent ductile lumen to the interstitial tissue is significantly low compared to controls
Copper IUDs prevent pregnancy by
preventing implantationmaking the uterus toxic to sperm
injection of depo-provera or the insertion of an implant releasing progestin prevents pregnancy by
maintaining low and relatively constant concentrations of FSH and LH in the bloodblocking ovulation
as an emergency contraceptive, plan B, the injection of a very high dose of progestin, is only effective in a woman under certain conditions:
she has not ovulatedshe weighs less than 177 lbs
Delta 5 pathway
theca layer- DHEA
Delta 4 pathway
granulosa layer- P4
Which two proteins are involved in spermatozoa-oocyte fusion
Izumo on the inner acrosomal membrane and CD9 on the egg membrane
A dog presents at your veterinary clinic and has the following diagnostic findings as compared with a diagnostic assessment just 2 days prior: increasing progesterone, decreasing estradiol and 100% cornified superficial vaginal epithelial cells. This dog is in which phase of the estrous cycle?
estrus
sperm chemotaxis is
directed movement in response to a chemical gradient
Sperm plasma membranes are "scrubbed" by mucous in the ______________which results in removal of ______________.
cervix, membrane sterols
In cryopreservation, a _____________ replaces ___________ in the sperm head so that during freezing ice crystals are not formed.
permeable cryoprotectant, water
Which of the following is not true about cortical granule exocytosis?
it results in depolarization of the egg
Which of the following is not an accessory sex gland in human males?
prostatic urethra
A tom presents at your veterinary clinic for fertility assessment. On physical exam you note that he does not have any penile spines. What can you directly conclude from this finding?
he will have low serum testosterone he will be unlikely to stimulate ovulation on copulation
The correct order of events in spermatozoa chemotaxis in the sea urchin is:
resact binds to GC, cGMP increases, intracellular Na+ increases, intracellular Ca+2 increases, tail begins to move
Which of the following pairs is not correct?
salamanders - allurin-like proteins
What is unique about ovulation, fertilization, and pregnancy in the dog as compared with other animals?
An MI oocyte is ovulated
The process of sperm maturation results in spermatozoa that:
are motilepossess a distal cytoplasmic droplet
The end result of sperm capacitation is:
tyrosine phosphorylation and hyperactive motility
A scientist develops a drug to prevent the acrosome reaction; this would be a useful contraceptive because:
sperm-egg fusion is impaired because Izumo is on the inner acrosomal membrane
__________ response is needed for erection and __________ response is needed for ejaculation.
parasympathetic; sympathetic
Calculate the number of insemination doses you would have if you had the following semen parameters in a cow:Ejaculate volume=4 mlSperm concentration= 200 million/mlProgressive motility= 75% Desired concentration of motile sperm per straw= 20 million/dose
30
In porcine IVF done in a lab setting, hyaluronidase is added to oocytes prior to insemination. What role does this enzyme play in fertilization?
it digests the cumulus cell extracellular matrix
Viagra prolongs an erection by:
inhibiting phosphodiesterase
semen extenders do not
decrease the volume of the original ejaculate
Which of the following is not a function of the epididymis?
production of clotting enzyme
In amphibians and sea urchin the vitelline envelope is the same thing as the____________________ in mammals.
zona pellucida
Equilibration is the time needed for spermatozoa and egg yolk:citrate in an cryoprotectant to mix effectively, for ___________ to be more effective, and for ____________ to enter the cell.
antibiotics, cryoprotectant
What is the difference between pseudopregnancy in the dog and the cat?
It is the same length as pregnancy in the dog but shorter than pregnancy in the cat
A cat just came out of estrus and it is late fall. If she was not bred, what phase of her estrous cycle is she most likely to enter this time of the year?
anestrus
Insufficient vaginal stimulation in the cat prevents ovulation by:
short-lived LHinadequate GnRH releaseinsufficient LH binding
The outward expression of estrus is dependent upon
estradiol produced by the graafian follicles
the estrus cycle differs from the menstrual cycle in the following way. The characteristic you check pertains to the ESTRUS cycle
the follicular phase is shorter
A major difference between spontaneous ovulates with long cycles and induced ovulates is
occurrence of pseudopregnancy
Pseudopregnancy serves an important function in the reproduction of species
allows time for the embryo to signal its presence so that the CL can be maintained
steroids are
small molecules (mol. wt. 300-350)
birds eating bugs contaminated with DDT laid soft shelled eggs because
DDT caused the liver to increase the metabolism of estrogen thus lowering blood estrogen concentrations
the 2 cell theory is different between birds and mammals in the following way
the granulosa synthesizes progesterone and the theca synthesizes androgens and estrogens
inhibin and activin differ how
inhibit acts on the anterior pituitary to decrease FSH production
the surface epithelium which covers the ovary is
the primary site for ovarian cancer