Puberty & Female Estrous Cycle Flashcards
Describe puberty.
-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
What mediates puberty?
-hypothalamus maturation = GnRH secretion/synthesis
-no intrinsic immaturity of gonads & pitutary
-can be forced to ovulate via pituitary transplants
Describe the female estrous cycle.
-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
Describe the hormones in the hypothalamo-hypophyseal-ovarian axis.
GnRH
FSH
LH
Estrogen
Progesterone
Testosterone
Inhibin
PGF2α
Oxytocin
What is the endocrine of the estrous cycle regulated by?
- Hypothalamus = GnRH
- Hypophysis = FSH & LH
- Ovary = estradiol, progesterone, inhibin
- Uterus = prostaglandin F2a (PGF2a)
Describe the ovary medulla VS cortex.
Medulla = vasculature, nerves, CT
Cortex = oocytes, follicles, CL
Describe the 4 diff types of follicles.
- Primordial = oocyte surrounded by 1 layer of squamous cells
- Primary = oocyte surrounded by 1 layer of cuboidal cells
- Secondary = oocyte surround by 2+ layers & zona pellucida
- Antral = fluid formed by follicular cells
Describe folliculogenesis: primordial & committed follicles.
-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
What are the 3 stages of folliculogenesis?
- Emergence 4 mm
- Deviation 8 mm
- Ovulation 10-20 mm
Describe antral follicle.
*gonadotropin dependent
1. theca externa = CT
2. theca interna = produce androgen via LH
3. Granulosa cell = produce estrogen, inhibin, follicular fluid via FSH
Describe corpus hemorrhagicum, corpus luteum, corpus albicans.
- CH = after ovulation, antrum falls & fills w blood
- CL = theca interna & granulosa proliferate into luteal cells & make progesterone
>lg luteal = granulosa - secrete oxytocin & relaxin
>sm luteal = theca interna - CA = old CL (not functional)
Describe the hypothalamus.
- Tonic = GnRH pulses in M & F
- Surge = F only. Burst of GnRH for LH surge
- Paraventricular nucleus = oxytocin synthesis
Describe the feedback in the hypothalamus.
- Estradiol = pos feedback in surge center -> makes GnRH -> release LH -> ovulation
- Progesterone = neg feedback in surge & pos feedback in tonic via FSH & LH -> follicle development
Describe the female estrous cycle in a non pregnant species.
Describe the species differences of PGF2a.
*induces luteolysis
-cows = one horn effects only that ovary
-mare = uterus affects both ovaries
Describe seasonality.
-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)
Describe the cow estrous cycle.
-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
What are the signs of estrus in the cow?
-standing to be mounted
-clear vag mucus
-increase activity
-bellow
-decrease milk
Describe the follicular dynamics in the cow.
-follicle growth in waves
-# varies in species
1. Recruitment
2. Selection
3. Dominance
4. Atresia
Describe the estrous cycle in the ewe.
-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
Describe the estrus cycle in the doe.
-21d
-seasonal polyestrous
-short day
-estrus 12-24h
-ovulation 12-36h after start of estrus
-luteolysis like cow
-puberty 6-8mo
Describe the female estrous cycle in the sow.
-21d (no follicular wave development)
-polyovulatory
-polyestrous
-non seasonal like cow
-estrus 2-4d
-ovulation in last 24h of estrus
-puberty 7 mo
Describe the female estrous cycle in the mare/Jennie’s.
*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
Describe the estrous cycle of camelids.
-nonseasonal
-polyestrous
-induced ovulation triggered by factors in seminal plasma
-overlapping follicular waves every 12-14d
-puberty 5mo-2yr
