Flashcards in Repro - Female 1 Deck (85):
What is the primary site of steroid AND protein synthesis?
Follicles are classified in an ________ progression.
What are the layers of the Graafian follicle?
theca externa, theca interna, granulosa cells
What do follicles house?
What is the difference between oogenesis and folliculogenesis?
Oogenesis is the prenatal phase.
Folliculogenesis is the prepubertal phase.
When are folliculogenesis and oogenesis both occurring?
During differentiation in the pubertal phase.
What is oogenesis?
the process by which female gametes are generated
Oogenesis occurs independently of folliculogenesis. True or false?
How is the product of oogenesis different than spermatogenesis (besides the obvious)?
Oogenesis leads to formation of haploid cell that builds up a store of enzymes, mRNAs, organelles, and metabolic substrates
Ovum is non-motile. True or false?
When are oogonia referred to as oocytes?
Upon entering meiotic division.
When are oocytes arrested?
At the diplotene stage, also known as dictyate stage of meiosis
What are primordial follicles?
spindle-shaped epithelial cells that surround oocytes
How many oocytes are in the canine, bovine, and porcine ovaries at birth?
porcine & canine- 700,000
Folliculogenesis occurs during the ________ phase.
Few follicles grow during prepubertal phase, these follicles do not undergo ______ and become ______.
After birth, oocytes continue to ___.
How do the number of oocytes change as a dog ages?
decrease; 700k at birth to 33k at 5 years, to 500 at 10 years
What initiates transition from primordial to primary follicles?
kit ligand (KL)
leukaemia inhib. factor (LIF)
bone morphogenic proteins (BMPs)
keratinocyte growth factor (KGF)
basic fibroblast growth factor (bFGF)
What has a negative impact on the transition from primordial to primary follicles?
Anti-Mullerian hormone (AMH)
How many follicles begin to grow?
Do all growing follicles become Graafian follicles?
What happens to follicles that do not become Graafian follicles?
They undergo atresia
When does follicular atresia occur?
Any step during folliculogenesis
What signals atresia to occur?
lack of support signal
More than ___% of follicles and oocytes degenerate during germ cell development.
What follicles constitute the higher proportion of follicles that undergo atresia?
What follicle stages are FSH independent?
primordial, primary, and secondary follicles
What follicle stages are FSH-responsive?
preantral to antral
What follicle stages are FSH-dependent?
Gonadotropin dependent follicles have a high rate of atresia in the ewe. True or false?
What are the two patterns of follicular development?
dominant, ovulatory-size follicles develop throughout the estrous cycle
dominant ovulatory-size follicles develop only during follicular phase
Which animals only have follicular development during the follicular phase?
Which animals have follicular development throughout estrus?
cattle, sheep, horses
What is the basis of selection of dominant follicle?
What are the intrafollicular mechanisms in cattle?
Free IGF-I and estradiol levels
LH receptor number on granulosa cells
What are the intrafollicular mechanisms in horses?
Free IGF-1, Estradiol, inhibin-A, and activin-A are the deciding factors for the selection of dominant follicle
What about growth and maturation of oocytes?
Oocytes have contact with granulosa cells and are completly dependent on them for growth.
How do oocytes and granulosa cells communicate?
cytoplasmic connections transfer metabolic substances
What is the cAMP Theory for Oocyte Maturation and Ovulation?
cAMP is transferred from the follicular granulosa cells to the oocyte
High levels of cAMP in the oocyte ____ oocyte maturation.
Low levels of cAMP in the oocyte ______ oocyte maturation.
LH surge prior to ______ stimulates synthesis of ________ in the granulosa cells.
ovulation; hylauronic acid
What disrupts the contact between granulosa cells and the oocyte? What does this result in?
hylauronic acid; no more transfer of cAMP frm granulosa cells to oocyte
Why are low levels of cAMP critical?
critical for resumption of meiosis
After LH surge, _______ occurs and _______ oocyte at MII is released.
What is the exception to cAMP theory?
Dog, fox- at the time of ovulation, primary oocyte at metaphase I is released
After ovulation, primary oocyte at M1 rapidly completes its 1st meiotic division
What is the end result of the cAMP theory?
Germinal vesicle breaks down and first meiotic division is complete and first polar body is released.
The first polar body has an excess of cytoplasm. True or false?
False- very little cytoplasm
Where does ovulation take place in most mammals?
At random locations over the surface of either ovary.
In what species do ovulations occur more frequently from the left ovary? The right?
left- pig and camel
In what animal is the ovulation site restricted to a depression in the ovary called the fossa?
What is the half life of FSH?
When are androgens synthesized?
When are estrogens synthesized?
When are progeterones synthesized?
In which female do dominant antral follicles develop and undergo ovulation only in follicular phase?
As follicular maturation progresses, the ability of granulosa cells to aromatize androgens _____.
What are the physiological effects of low levels of estrogen?
positive feeback on FSH and LH secretion
What are the physiological effects of high levels of estrodiol?
positive feedback on LH secretion; LH surge
What are the physiological effects of VERY high levels of estradiol?
negative feeback on FSH and LH secretion
Etradiol regulates timing of uterine ____ secretion in what species?
PGF; cows and sheep
Estrogen causes growth and development of _____ for gamete transport.
When does estrogen production increase in the follicle and when is it highest?
increase in pre-ovulatory phase
highest at the time of LH/FSH surge
How does estrogen effect oxytocin?
increases oxytocin receptor number in endometrium
How does estrogen affect prostaglandin?
Estrogen does not effect development of mamary glands. True or false?
Progesterone is synthesized and secreted by what?
Preovulatory surge of LH results in what? (related to progesterone synthesis and secretion)
luteinization of granulosa and theca cells
What are the postive effects of luteinization of granulosa and theca cells?
increase synthesis of DESMOLASE and 3b-HYDROXYSTEROID DEHYDROGENASE
What are the inhibitory effects of luteinization of granulosa and theca cells?
Decrease synthesis of 17a-HYDROXYLASE
Why is the bitch unique in regards to progesterone?
1. progesterone produces before ovulation because lutenization occurs before ovulation
2. pseudopregnany because functional corpus luteum persists in unmated animals and after infertile mating
In what species is the diestrus phase the same as the gestation period? How long is it?
dog; 60-70 days
What is clinical pseudopregnancy?
exaggeration of normal physiological PP
Lactating PP bitches are under the influence of _______.
Progesterone inhibits ________ contraction and prevents ________.
Where does progesterone primarily act? What hormones does progesteron inhibit?
the hypothalamus; LH/FSH
Decreasing levels of progesterone has a positive feedback on ___ and ___ from the AP after the end of _____.
FSH; LH; diestrus
When does corpus luteum regress?
Only when CL acquires the capacity for luteal regression.
What is luteolysis?
regression of CL
Can a CL undergo lysis at any time?
It is acquired on day 7 in cows and day 13 in pigs (post ovulation)
What is the purpose of PGR2a?
It will cause luteolysis of the CL
How is PGR2a used in cats and dogs?
It is ineffective in cats and has limited efficacy in dogs
What is the mechanism of luteolysis?
termination of CL by the luteolytic agent, PGF2a, of uterine origin