Reproduction Cyclicity

Question 1

what is puberty followed by in females

Answer 1

reproductive cyclicity

Question 2

Estrus (heat)

Answer 2

characterized by endocrine changes, behavioural changes, sexual receptivity and physical and structural changes in the reproductive tract

Question 3

whcih species undergo Polyestrus

Answer 3

cow, cat, pig, rodent

Question 4

what species undergo seasonally polyestrus

Answer 4

long day breeder: mare
short day breeder: sheep

Question 5

what does seasonally polyestrus mean

Answer 5

clusters of estrous cycles during a certain peiod of the year

Question 6

what does monoestrus mean

Answer 6

one cycle per year

Question 7

what species are monoestrus

Answer 7

dog, wolf, fox, bear

Question 8

what does polyestrous mean

Answer 8

uniform distribution of estrous cycles throughout the year

Question 9

what are the 4 stages of the estrous cucle of the cow

Answer 9

proestrus
estrus
metestrus
diestrus

Question 10

what stages of the estrous cycle are considered the follicular phase? what kind of follicle persists

Answer 10

follicular phase = proestrus and estrus
- follicle is predominant

Question 11

what 2 stages of estrous are considered the luteal phase. what type of follicle is predominant

Answer 11

luteal phase = metestrus and diestrus. CL is predominant

Question 12

what is the predominant hormone at ovulation

Answer 12

estrogen

Question 13

what are some physical changes in the reproductive tract during estrus

Answer 13

• increased blood flow
• increased edema of tissues (external genetalia)
• mucus secretion from cervix and caudal vagina
  -elevated urine tone due to smooth muscle contraction
  -growth of uterine glands
• hyperemia

Question 14

what effects does the LH surge have on the oocyte

Answer 14

promotes maturation of oocyte (progression of meiosis) prior to ovulation, induces breakdown of cytoplasmic processes allowing oocyte to resume meiosis
- primary oocyte arrested at meiotic prophase completes its first meiotic division under the influence of LH

Question 15

what is the cardinal sign of estrus in a cow

Answer 15

standing estrus: cow allows mating or stands in a characteristic mating posture to be mounted by herd mates

Question 16

Proestrus

Answer 16

2-5 days immediately preceding behavioural estrus, ovulatory follicles develop, secretes E2

Question 17

Estrus

Answer 17

shortest stage, period of sexual receptivity and maximum e2 secretion

Question 18

Metestrus

Answer 18

period of CL development and beginning of P4 secretion

Question 19

what day does the CL become fully functional

Answer 19

Day 5 (day 0 = day of estrus)

Question 20

Diestrus

Answer 20

presence of fully functional CL, ends with luteolysis

Question 21

in mammals, what is the ovulated egg (what stage is it arrested in, and what kind of oocyte)

Answer 21

secondary oocyte with nucleus arrested at metaphase II

Question 22

when does the ovulated egg in a mammal progress past metaphase II

Answer 22

when sperm makes contact with its cytoplasm

Question 23

How does LH have an effect on follicular pressure

Answer 23

LH surge will to an increase in production of PGE2 (a prostaglandin). –> promotes histamine production –> increase blood flow to ovary –> increased hydrostatic pressure in follicle –> increase follicular pressure

Question 24

what effect does PGF2 alpha have on ovulation

Answer 24

induse contractions of ovarian smooth muscle –> increase follicular pressure

also induce release of lysosomal enzymes from granulosa cells of the follicular wall –> follicular wall weakening

Question 25

following the LH surge, what begins to synthesize P4

Answer 25

theca internal cells

Question 26

increased progesterone levels following an LH surge results in what to make the follicular wall even weaker

Answer 26

production of collagenases in theca internal --> break down collagen fibers and connective tissue of the tunica albuginea

Question 27

what is a stigma

Answer 27

avascular region that develops on the follicular wall which ruptures and releaases the oocyte and follicular fluid

Question 28

after ovulation, what does the remaining follicular structure become

Answer 28

corpus leuteum

Question 29

histologically, what 2 types of cells are contained within the CL

Answer 29

theca and granulosa cells

Question 30

what is the corpus luteum

Answer 30

a transient endocrine gland

Question 31

thecca cells become _____ in the CL

Answer 31

small luteal cells

Question 32

granulosa cells become ____ in the CL and contain _____ and ____ (2 hormones)

Answer 32

granulosa cells become large luteal cells in the CL and contain relaxin and oxytosin

Question 33

small luteal cells and large luteal cells both produce

Answer 33

P4

Question 34

what are 4 luteotropic agents

Answer 34

LH, prolactin, eCG, hCG

Question 35

when does the CL stop increasing in size

Answer 35

in the middle of the cycle

Question 36

through what mechanisms does the CL increase in size

Answer 36

hypertrophy of large luteal cells (formerly granulosa) hyperplasia of small luteal cells (formerly theca)

Question 37

what are 3 target organisms of P4

Answer 37

1. hypothalamus 2. mammary gland 3. uterus (myometrium and endometrium)

Question 38

what is the mechanism for P4 synthesis in the corpus luteum

Answer 38

* LH activates protein kinases * Internalization of LDL-Cholesterol- receptor * Release of cholesterol esters from its receptors * Release of cholesterol from cholesterol esters * Conversion of cholesterol to pregnenolone in the mitochondria * Conversion of PREG to P4 in the cytoplasm

Question 39

what is luteolysis

Answer 39

regression of the CL, usually towards the end of diestrus

Question 40

what effect does the uterus have on luteolysis

Answer 40

the uterus synthesizes prostaglandin F2 alpha which is a luteolytic factor. if you remove the uterus or the ipsilateral horn that is producing the CL, the CL will persist for longer (aka wont get destroyed)

Question 41

what is the mechanism that ensures PGF2a from the uterus exerts its luteolytic activity on CL without being diluted

Answer 41

counter current exchange and passive diffusion between the uterine venous blood and ovarian arterial blood

Question 42

which species does not have counter current exchange of PGF2a from the uterus to the ovary

Answer 42

horses, PGF2a reaches ovary through systemic circulation

Question 43

lyteolysis is characterized by a dramatic drop in which hormone

Answer 43

p4

Question 44

what hormones control luteolysis

Answer 44

P4, oxytocin, and PGF2a

Question 45

what 2 hormones are important for the synthesis of oxytocin receptors in the uterus

Answer 45

P4 and E2

Question 46

why is the expression of oxytocin receptors in the uterus important

Answer 46

oxytocin secreted by the CL must act on uterine endometrium for the synthesis of PGF2a in a pusatile manner

Question 47

what stimulates the growth of a cohort of factors. what do these growing follicles effect

Answer 47

high FSH, Low LH - produces small amounts of E2 and inhibin, both inhibitory to the pituitary

Question 48

under what conditions do selected follicles grow

Answer 48

Low FSH, moderate LH, moderiate inhibin

Question 49

how many selected follicles become dominant

Answer 49

1 or 2

Question 50

what are the 3 phases of decelopment for a dominant follicle

Answer 50

1. growth, stasis and regression and ovulation

Question 51

what does the dominant follicle produce

Answer 51

estradiol to threshold levels --> in absence of p4, this will induce surge of GnRH from surge center with codominant surge of LH --> ovulation

Question 52

what hormone determines wether the dominant follicle will undergo atresia or ovulation

Answer 52

P4