Repro 2: Puberty

Puberty

Process of acquiring reproductive competence

Hypothalamic neurons, GnRH

The onset of puberty depends on the ability of ___ to produce ___.

Surge center, tonic center

What does the female hypothalamus contain?

Tonic center

What does the male hypothalamus contain?

Amplitude, frequency

• Before puberty in the female and male

  • GnRH neurons in both the tonic center and the surge center of the hypothalamus release low ___ and low ___ pulses of GnRH

Higher, increases

• After puberty in the female only

  • Tonic center controls basal levels of GnRH, but they are ___ than in the prepubertal female because the pulse frequency ___

Surge center

• Controls the preovulatory surge of GnRH

• The male does not develop this

During puberty

When does secretion of LH surge?

High-amplitude, basal

Females have ___ preovulatory episodes of LH once every several weeks and ___ pulsatile episodes between the large preovulatory surges.

Small, testosterone

Males have ___ LH episodes that occur every 2 to 6 hours.

___ is secreted soon after each LH episode.

Decreased hypothalamic sensitivity to negative feedback by testosterone/estrogen

Cause of onset of puberty of males

Body maturation, amount of body fat, nutrition, environmental and social conditions, season of birth, photoperiod

What are important factors that are important in regulating onset of puberty in females?

Delays

Being in small groups ___ (accelerates/delays) the onset of puberty for females.

Accelerates

Exposure to a male ___ (accelerates/delays) the onset of puberty for females.

Accelerates

High growth rate ___ (accelerates/delays) the onset of puberty for females.

Estrous cycle, menstrual cycle

Among mammals, reproductive cyclicity consists of the ___ and the ___.

Polyestrus, seasonally polyestrus, monoestrus

Three types of cyclicity

Estrogen

Dominant hormone in follicular phase that is produced by follicles

Progesterone

Dominant hormone in luteal phase that is produced by corpora lutea

Follicles

Dominant ovarian structure of follicular phase

Corpora lutea

Dominant ovarian structure of luteal phase

Luteal phase

Which phase of the estrous cycle takes up the majority (~80%) of the cycle?

Follicular phase

Proestrus + estrus

Proestrus

Formation of ovulatory follicles + estrogen secretion

Estrus

Sexual receptivity + peak estrogen secretion

Luteal phase

Metestrus + diestrus

Metestrus

Corpora lutea formation and beginning of progesterone secretion

Diestrus

Sustained luteal secretion of progesterone

Anestrus, proestrus, estrus, diestrus

Phases of estrous cycle in female dog

Anestrus

• Condition when the female does not exhibit regular estrous cycles

• Ovaries are relatively inactive, and neither ovulatory follicles nor functional corpora lutea are present

• Result of insufficient GnRH release from hypothalamus to stimulate and maintain gonadotropin secretion

Silent ovulation

Ovary develops follicle(s) that will often ovulate without an accompanying behavioral estrus following seasonal anestrus in the ewe or pregnancy in the cow

Progesterone

The corpus luteum produced from the ovulatory follicle from the silent ovulation secretes ___ that “primes” the brain.

Estradiol, estrus

The priming of the brain by progesterone enables ___ secreted by the next ovulatory follicle to elicit a full behavioral ___.

Menses (menstruation)

Commonly referred to as the menstrual period

Defined as the sloughing of the endometrium to the exterior

Ovarian cycle, endometrial cycle

Parts of menstrual cycle

True

True or false?:

In the menstrual cycle, there is no defined period of sexual receptivity.

Menses

The timeline for description of the cycle begins and ends with ___, not ovulation or estrus.

Menses (5 days) + proliferative phase (9 days)

Parts of follicular phase

Luteal phase

Equals secretory phase (14 days)

B

What hormone is predominantly secreted during proestrus?

A) Progesterone

B) Estradiol

C) Testosterone

D) Cholesterol

E) Inhibin

D

The trigger for the onset of puberty is located in:

A) The ovary or testis

B) The anterior pituitary gland

C) The posterior pituitary gland

D) The hypothalamus

E) None of the above

E

The menstrual cycle consists of the sequence:

A) Diestrus, proestrus, estrus, metestrus

B) Estrus, diestrus, metestrus, proestrus

C) Metestrus, proestrus, estrus, anestrus

D) Proestrus, estrus, postestrus, diestrus

E) None of the above

B

Monoestrous, seasonal breeder, long luteal phase

A) Domestic cow

B) Dog

C) Horse

D) Sheep

E) Only B and C are correct

C

Ovulation in cats:

A) Occurs 10-14 days after the onset of estrus

B) Occurs 10-14 hours after the onset of estrus

C) Is induced by copulation

D) Is unusual in that is always occurs during diestrus

E) All of the above

B

Which species is nonseasonally polyestrous and has an estrous cycle lasting 21 days?

A) Mare

B) Cow

C) Female dog

D) Queen

E) None of the above

D

Which phase of the normal, nonpregnant bovine estrous cycle is of the longest duration?

A) Estrus

B) Proestrus

C) Metestrus

D) Diestrus

E) Anestrus

A

In the male, hypothalamic GnRH secretion after puberty is from:

A) Tonic center

B) Surge center

C) Both tonic and surge center

D) Paraventricular nucleus

E) All of the above

E

In the menstrual cycle, sexual receptivity is most pronounced during:

A) Follicular phase

B) Luteal phase

C) Proliferative phase

D) Secretory phase

E) None of the above

D

Melatonin from the pineal gland regulates the estrous cycle in:

A) Sheep

B) Mares

C) Cows

D) Only A and B

E) A, B, and C

C

It is possible to induce cyclicity during anestrus by administration of exogenous:

A) Progesterone

B) Estradiol

C) GnRH

D) FSH

E) PGF2 alpha

A

In primates, menstruation ends when the endometrial lining begins to regrow. What stimulates the regrowth of the endometrial cells?

A) Estrogen

B) Progesterone

C) LH
D) FSH

A

Which hormone stimulates testosterone production in males?

A) LH

B) FSH

C) Estrogen

D) Oxytocin