Chapter 6

Question 1

Females exhibit greater selectivity than males in

Answer 1

mating-partner choice

Question 2

During breeding seasons, male vertebrates are capable of

Answer 2

sexual behavior all the time

Question 3

During breeding seasons, male vertebrates are capable of sexual behavior all the time.In contrast, females exhibit

Answer 3

great fluctuations in sexual behavior

Question 4

Estrus and anestrus

Answer 4

Female can be both estrus and anestrus : when ready to mate female is estrus, the rest of the time the female is anestrus, estrus females are more attracted to males than when they are anestrus: estrus spend more time near and looking for males than anestrus

Question 5

Females find males more attractive when in

Answer 5

estrus

Question 6

Males find females in __ more attractive than __ females

Answer 6

Males find females in estrus more attractive than anestrus females

Question 7

Males prefer to mount

Answer 7

estrus females

Question 8

Only __ females will permit mating to take place

Answer 8

estrus

Question 9

__ are involved in expression of estrous behaviour in rats and dogs

Answer 9

the ovaries

Ovaries are the main source of estrogen + progesterone: impact on periphery but also on CNS

Question 10

in females, hormones associated with __ maturation affect nervous system underlying mating behaviour

Answer 10

Hormones associated with ova maturation affect nervous system underlying mating behavior
(Hormones associated with ova maturation affect nervous system underlying mating behavior)

Question 11

length estrous cycle

Answer 11

4 or 5 days

Question 12

estrous cycle can be divided into 3 stages:

Answer 12

Diestrus (48 h)
Vaginal Proestrus (12 h)
Vaginal Estrous (36h)

Question 13

length of diestrous component of estrous cycle

Answer 13

about 48h

Question 14

what happens during diestrus 1

Answer 14

follicles are developped

Question 15

what characterizes Diestrus 2:

Answer 15

Fully developed egg with granulosa and theca cells: but not released

Question 16

what is the length of vaginal proestrus

Answer 16

12h

Question 17

what happens during vaginal proestrous

Answer 17

This is when ovulation occurs and egg is released into fallopian tube

Question 18

what is the length of vaginal estrous

Answer 18

about 36h

Question 19

what happens during vaginal estrous

Answer 19

The corpea luteum (remainder of follicle after egg was released)
This structure can further develop if there is further copulation

If there is no copulation will degrade
Corpus luteum is important in secreting progesterons and plays a role into implantation of egg into uterine wall (if fertilization)

Question 20

The female is ready to mate at which stage of estrous cycle

Answer 20

vaginal proestrous

Question 21

what happens in ovaries is reflected in __

Answer 21

behaviour
ex: female is most receptive during ovulation

Question 22

ovulation occurs when female is the most receptive in terms of

Answer 22

behaviour

Question 23

area that is bigger in females

Answer 23

anteroventral periventricular nucleus

Question 24

why is anteroperiventricular nucleusof males smaller than females ?

Answer 24

males early on produce androgens: testosterone travels in blood to brain: diffuse in the membrane of neurons (steroids are lipophilic and can pass through membrane). Inside the neuron they are converted to estradiol, which binds to its receptor (forms steroid-receptor complex) and binds to DNA in presence of coregulator: inducing apoptosis

females do not produce androgens as much early on: so this does not happen

Question 25

APVN (anteroventral periventricular nucleus) plays an important role :

Answer 25

in hormonal surge for ovulation to occur + for female to be receptive

Question 26

kisspeptin binds to its receptor on neurosecretory cells in __ those cells when kisspeptin bound start producing __

Answer 26

Kisspeptin: binds to receptor on neurosecretory cells in hypothalamus: those cells when kisspeptin bound start producing gonadotropin releasing hormones: GTRH

Question 27

Describe what happens when FSH and LH bind to female gonads

Answer 27

LH bind on Thecca cells and produce androgens (testosterone), testosterone converted into estrogen in granulosa cells through aromatase (aromatase active when FSH is bound to granulosa cells) LH can bind to granulosa cells and produce progesterones as well

Question 28

two important brain regions in regards to surge / positive feedback in females

Answer 28

anteroPeriventricular Nucleus superchiasmatic nucleus (SCN)

Question 29

APV receives input from SCN which allows

Answer 29

apv to time its release of kisspeptin

Question 30

APV really important because leads to

Answer 30

surge in hormones

Question 31

Once every cycle: sex steroid hormones produced by females gonads instead of putting break on further release lead to

Answer 31

even more release by impacting APV: at that point in time that region (because of projections from SCN is ready to release kisspeptin) Kisspeptin binds to neurosecretory cells that release GTRH SCN also has receptors for estrogen

Question 32

female is most receptive when

Answer 32

in vaginal proestrus (female is "estrus" in vaginal proestrus)

Question 33

what happens during vaginal proestrous

Answer 33

surge in LH: LH by binding to thecca cells in gonads leads to production of testosterone (which is then converted to an estrogen like we have seen):rgis increases levels of estrogens slowly but surely: then there is a spike in estrogen: spike involves kisspeptin and positive feedback (ventralperiventricular nucleus +SCN)

Question 34

During proestrous: surge in LH: LH by binding to theca cells in gonads leads to production of testosterone (which is then converted to an estrogen): this increase levels of estrogen slowly but surely then spike in estrogen: spike involves kisspeptin and positive feedback: once egg released we go back to

Answer 34

negative feedback:

Question 35

Why FSH always high :

Answer 35

involved in development of the follicle throughout cycle , not only involved in hormone production also involved in development of follicle which contains the egg

Question 36

during vaginal proestrous we see spike in estrogen and we also see spike in:

Answer 36

progesterone (remember: estrogen + progesterone best match for female to engage in lordosis and in that order): spike in progesterone happens AFTER spike in estrogen (sequence is important in regards to ovulation and behaviour -lordosis) Once ovulation occurs, estrogen dramatically decreases, progesterone decreases slower

Question 37

during the rest of the time (aka outside proestrus when female is no longer estrous) neurosecretory cells that produce GTRH are still activate in part by kisspeptin its kisspeptin coming from

Answer 37

arcuate nucleus

Question 38

In both sexes: kisspeptin from __ involved in negative feedback

Answer 38

arcuate nucleus

Question 39

6 Basic components to mammalian female production

Answer 39

* Courtship * Mating * Ovulation * Pregnancy * Parturition (giving birth) * Lactation

Question 40

Females spend more time in __ phase than in __ phase

Question 41

Beach’s (1976) scheme of female sexual behavior (3)

Answer 41

* Attractivity * Proceptivity * Receptivity (lordosis)

Question 42

Beach's scheme of female sexual behaviour: describe (1/3): attractivity

Answer 42

attractivity is related to males: how attractive the female is to the male

Question 43

How can you measure attractivity?

Answer 43

you can measure that is by place preference: you have two females one in a specific chamber and male in middle: allow male to roam around: then the male you can measure and see how much time the male spends with who:

Question 44

baboons find females with __ attractive

Answer 44

baboons find females with enlarged genitals attractive

Question 45

Describe the study that was done to measure attractivity

Answer 45

6 different male monkeys were presented with ovariectomized female (same female was treated with estrogens or no estrogens)

Question 46

What was the conclusions of the attractivity study with monkeys?

Answer 46

obviously all monkeys preferred female when treated with estrogens: however they had different ratings : sp hormones are important for attractivity but it is not the only thing involved

Question 47

__ seem to be involved in attractivity, but non-hormonal factors as well

Answer 47

steroid hormones seem to be involved in attractivity, but non hormonal factors as well

Question 48

describe proceptivity

Answer 48

-Reflects female’s underlying motivational state * Observed in female’s efforts to establish and maintain proximity to males Also in alternating approaches and withdrawals by the female

Question 49

proceptivity can be observed in:

Answer 49

female’s efforts to establish and maintain proximity to males

Question 50

What are the three types of alternating approachers and withdrawals by the female during proceptivity

Answer 50

full solicitation partial solicitation interception

Question 51

describe the study they did to determine that hormone (estrogen) was important in proceptive behaviour

Answer 51

3 groups: (1)ovariectomized + estradiol (2)ovariectomized, no estradiol "control" (3)nonpregnant "control' measured proceptive behaviour (approach/contact/groom/presentation) use a male that is not in breeding season (females not in breeding season either, but one of the group is artifiically put in one by estrogen) despite male not showing interest in femal, females treated with estrogen still engage in behaviour

Question 52

All these type of solicitation behaviours involve

Answer 52

hormones; estrogen

Question 53

are hormones important in proceptive behaviour?

Answer 53

yes

Question 54

describe receptivity (3/3)

Answer 54

* The consummatory phase * Female reactions that are necessary and sufficient for fertile copulation * Much evidence as to the role of estrogen in receptivity (estrogen, progesterone and sensory stimuli from mounting of male all important in lordosis)

Question 55

important brain regions in lordosis

Answer 55

in hypothalamus : MPOA but MOST IMPORTANTLY VENTRAL MEDiAL NUCLEUS (VMN) estrogen binds to receptors in VMN -> medial regions of the brain (midbrain central gray + midbrain reticular formation) -> medullar reticular formation -> spinal cord -> motor neurons (ventral horn) ->deep back muscles

Question 56

Describe the study done on Estrogen Receptors

Answer 56

Study Summary: Estrogen Receptors and Female Sexual Receptivity Objective: To investigate the role of estrogen receptors, specifically estrogen receptor alpha (ERα), in female sexual receptivity using knockout mice. Method: Subjects: Female mice either: Knockout (ERα -/-): Lacking estrogen alpha receptors Control: Normal expression of ERα All mice were ovariectomized (removal of ovaries to eliminate endogenous hormone effects) Two hormone treatments administered: Estrogen alone Estrogen + progesterone Results: Controls: Showed sexual receptivity (lordosis behavior) in both treatments, especially with estrogen + progesterone. Knockouts: Showed no receptivity or lordosis at all, regardless of hormone treatment. Conclusion: Estrogen alone is not sufficient — estrogen must bind to ERα to promote sexual receptivity. ERα is critical: Knockout females lacking ERα do not respond to hormonal cues. This supports the idea that receptor presence (not just hormone availability) is essential for behavior. Additional Experiment: To rule out male behavior differences: Researchers measured the number of mounts by males toward both knockout and control females. Males mounted both types of females equally. However, there was no intromission with knockouts, confirming that the issue lies with female receptivity, not male interest.

Question 57

describe the role of estrogen in promoting lordosis (3 hypothesis)

Answer 57

(1) trigger hypothesis (2)maintenance hypothesis (3) cascade hypothesis

Question 58

describe the trigger hypothesis in regards to the role of estrogen in promoting lordosis

Answer 58

you only need acute injection or short lived treatment of estrogen to then observe lordosis later on

Question 59

describe the maintenance hypothesis in regards to the role of estrogen in promoting lordosis

Answer 59

Need constant treatment estrogen

Question 60

describe cascade hypothesis (role of estrogen in promoting lordosis)

Answer 60

need pretreatment estrogen, wait some time and then give another acute injection first injection: change nervous system second injection:hormones need to be there again to act on those changes:

Question 61

* Manipulations that mimic hormonal profile of estrus behavior in ovariectomized mouse/hamster: Inject with estradiol early one morning * Later inject with progesterone * Subsequently, female displays lordosis in response to the appropriate stimulation: difference in VMN estradiol implants and VMN estradiol + systemic progesterone injection

Answer 61

VMN estradiol implants → weak lordosis * VMN estradiol + systemic progesterone injection → lordosis as in natural estrus

Question 62

Estradiol priming leads to __

Answer 62

Estradiol priming leads to progesterone receptor production

Question 63

describe the study where knockout mice were used to examine the involvement of progesterone and estradiol

Answer 63

Objective: To assess how the absence of progesterone receptors (PR) affects female sexual receptivity (measured via lordosis quotient, LQ). Groups Compared: Wild type (+/+): Full expression of progesterone receptors Heterozygous (+/–): Partial expression of PRs PRKO (–/–): No progesterone receptors Experimental Design: All mice were primed with estrogen first (to mimic physiological hormonal sequence). Followed by progesterone administration alone. Lordosis quotient (LQ) was measured over 6 weeks as an index of receptivity. Results: Wild type: Showed a steady and strong increase in lordosis behavior, reaching ~80 LQ by week 6. Heterozygous: Moderate increase in LQ, plateauing slightly below wild type. PRKO (–/–): Barely responded; LQ stayed very low (~10 or less) across all weeks. Conclusion: Progesterone receptors are essential for normal sexual receptivity. Estrogen priming alone is insufficient; progesterone must bind to its receptor to trigger lordosis behavior. PRKO mice fail to exhibit lordosis, confirming the necessity of progesterone receptor signaling.