Puberty & Female Estrous Cycle

Question 1

Describe puberty.

Answer 1

-reproductive competence
-make gametes
-mating behavior
-make GnRH & LH
-decreased hypothalamic sensitivity to neg feedback by testosterone/estradiol = FSH
*cyclicity in females
*mature sperm in males

Question 2

What mediates puberty?

Answer 2

-hypothalamus maturation = GnRH secretion/synthesis
-no intrinsic immaturity of gonads & pitutary
-can be forced to ovulate via pituitary transplants

Question 3

Describe the female estrous cycle.

Answer 3

-one ovulation to the next
>follicular phase (ovulation)
>luteal phase (progesterone - CL)
>quiescent/anestrus phase (not making hormone/ovulate bc sick or seasonal etc)
*estrus defined by behavior

Question 4

Describe the hormones in the hypothalamo-hypophyseal-ovarian axis.

Answer 4

GnRH
FSH
LH
Estrogen
Progesterone
Testosterone
Inhibin
PGF2α
Oxytocin

Question 5

What is the endocrine of the estrous cycle regulated by?

Answer 5

1. Hypothalamus = GnRH
2. Hypophysis = FSH & LH
3. Ovary = estradiol, progesterone, inhibin
4. Uterus = prostaglandin F2a (PGF2a)

Question 6

Describe the ovary medulla VS cortex.

Answer 6

Medulla = vasculature, nerves, CT
Cortex = oocytes, follicles, CL

Question 7

Describe the 4 diff types of follicles.

Answer 7

1. Primordial = oocyte surrounded by 1 layer of squamous cells
2. Primary = oocyte surrounded by 1 layer of cuboidal cells
3. Secondary = oocyte surround by 2+ layers & zona pellucida
4. Antral = fluid formed by follicular cells

Preantral = dont require gonad hormone but antral do.

Question 8

Describe folliculogenesis: primordial & committed follicles.

Answer 8

-primordial follicle = origin of oocytes & follicular (granulosa) cells
>resting pool = inactive primordial
-committed follicle = 20-30 follicle grow per day
>gonadotrophin independent [FSH or LH] growth phase (preantral)
>follicle starts growth from resting pool
*subsequent growth requires gonadotropin support

Question 9

What are the 3 stages of folliculogenesis?

Answer 9

1. Emergence 4 mm
2. Deviation 8 mm
3. Ovulation 10-20 mm

Question 10

Describe antral follicle.

Answer 10

*gonadotropin dependent
1. theca externa = CT
2. theca interna = produce androgen via LH
3. Granulosa cell = produce estrogen, inhibin, follicular fluid via FSH

Question 11

Describe corpus hemorrhagicum, corpus luteum, corpus albicans.

Answer 11

1. CH = after ovulation, antrum falls & fills w blood
2. CL = theca interna & granulosa proliferate into luteal cells & make progesterone
   >lg luteal = granulosa - secrete oxytocin & relaxin
   >sm luteal = theca interna
3. CA = old CL (not functional)

Question 12

Describe the hypothalamus.

Answer 12

1. Tonic = GnRH pulses in M & F
2. Surge = F only. Burst of GnRH for LH surge
3. Paraventricular nucleus = oxytocin synthesis

Question 13

Describe the feedback in the hypothalamus.

Answer 13

1. Estradiol = pos feedback in surge center -> makes GnRH -> release LH -> ovulation
2. Progesterone = neg feedback in surge & pos feedback in tonic via FSH & LH -> follicle development

Question 14

Describe the female estrous cycle in a non pregnant species.

Answer 14

Question 15

Describe the species differences of PGF2a.

Answer 15

*induces luteolysis
-cows = one horn effects only that ovary
-mare = uterus affects both ovaries

Question 16

Describe seasonality.

Answer 16

-photoperoid
>perceived by retina
>melatonin made by pineal gland during dark
>synthesized from tryptophan
>increase GnRH in short day breeder like small ruminants (fall, winter)
>decrease GnRH in long day breeder like horses (spring, summer)

Question 17

Describe the cow estrous cycle.

Answer 17

-21d
-monovulatory
-ovulation = 10-15h AFTER end of estrus
>24-30h after estrus starts
-4 stages of behavior differences
1. Proestrus = follicular growth
2. Estrus = heat behavior, copulation
3. Metestrus = ovulation
4. Diestrus = progesterone phase

Question 18

What are the signs of estrus in the cow?

Answer 18

-standing to be mounted
-clear vag mucus
-increase activity
-bellow
-decrease milk

Question 19

Describe the follicular dynamics in the cow.

Answer 19

-follicle growth in waves
-# varies in species
1. Recruitment
2. Selection
3. Dominance
4. Atresia

Question 20

Describe the estrous cycle in the ewe.

Answer 20

-17d
-seasonal polyestrous
-short day
-first ovulation is silent (no signs)
-estrus lasts 36h
-ovulation 24-30h after start of estrus
-diestrus 14-15d
>luteolysis if no embryo 12d after ovulation

Question 21

Describe the estrus cycle in the doe.

Answer 21

-21d
-seasonal polyestrous
-short day
-estrus 12-24h
-ovulation 12-36h after start of estrus
-luteolysis like cow
-puberty 6-8mo

Question 22

Describe the female estrous cycle in the sow.

Answer 22

-21d (no follicular wave development)
-polyovulatory
-polyestrous
-non seasonal like cow
-estrus 2-4d
-ovulation in last 24h of estrus
-puberty 7 mo

Question 23

Describe the female estrous cycle in the mare/Jennie’s.

Answer 23

*jennie is not seasonal
-21d
-seasonal polyestrous
-monovulatory
-long day
-estrus 5-7d (low progesterone rather than estrogen)
-diestrus (high progesterone)
-diff LH potency
-ovulation in last 48h of estrus
-puberty 8-15mo

Question 24

Describe the estrous cycle of camelids.

Answer 24

-nonseasonal
-polyestrous
-induced ovulation triggered by factors in seminal plasma
-overlapping follicular waves every 12-14d
-puberty 5mo-2yr

Question 25

Describe the female estrous cycle of the bitch.

Answer 25

-no lutenization
-4-6mo
-polyovulatory
-ovulate immature oocytes (no fertilization)
-oocytes mature in oviduct (2-5d post ovulation -> ootid, after 2nd meiosis)
-puberty 6-12mo
-estrous cycle monitor:
>behavior
>vag cytology
>progesterone
>LH
-4 stages:
1. Proestrus = follicular growth, no heat behavior, bleeding
2. Estrus = heat behavior, copulation
3. Diestrus = progesterone phase 60d (preg or not)
4. Anestus = acyclic phase

Question 26

Describe the female estrous cycle in queens.

Answer 26

-seasonal polyestrous
-long day
-induced ovulation via penile spines (testosterone)
-proestrus 1-2d
-estrus 5-8d
-diestrus 30-70d
-puberty 6-10mo
>season
>weight
-detection of estrus
>vocal
>posture
>rubbing