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UCD / Animal Science / ANSC 002 / What are hormones in female reproduction?

What are hormones in female reproduction?

What are hormones in female reproduction?


School: University of California - Davis
Department: Animal Science
Course: Introductory Animal Science
Professor: James murray
Term: Spring 2016
Tags: animal and Science
Cost: 25
Name: ANS 2: Week 3 Notes
Description: These notes cover everything taught in Week 3's three lectures, including diagrams and charts from the lecture powerpoints
Uploaded: 04/16/2016
8 Pages 127 Views 2 Unlocks

ANS 2: Week 3 Notes

What are hormones in female reproduction?


● Hormones in Female Reproduction:

○ Hypothalamus → GnRH → anterior pituitary

○ Anterior pituitary → FSH + LH → ovary

■ LH stimulates ovulation

○ Ovary → causes corpus luteum to develop / causes ova to develop ■ Corpus luteum (CL)→ progesterone

■ Releases progesterone + becomes CA (scar where CL used to be) ■ Progesterone = vital for pregnancy (must be regulated)

○ Uterus: -pregnant or​-prostaglandin → CL regresses → NOT pregnant ○ Cells that were producing estrogen switch to produce progesterone ○ Humans can use hormones to control the cycling of animals

What is the meaning of the ovary?

● Embryo releases a “signal” to let mom know they’re there

○ Pigs have minimum 3 embryo - any less the signal isn’t “strong enough” ○ Signal → maintain CL → production of progesterone → keep pregnantIf you want to learn more check out What is alcohol use in american culture?

● ^Diagram ​WILL BE ON AN EXAM​(be able to recreate / label it) ○ Day 0 = when ovulation occurs (and again at day 20ish)

What is the meaning of progesterone?

○ Cycle = period from ovulation to ovulation

○ FSH = always “wandering” in the background (levels not cyclical) ○ Progesterone: We also discuss several other topics like Is the power series infinite?

■ Loss of CL → drop in progesterone (day 0)

■ After ovulation: new CL forming → rise in progesterone

○ Estrogen: We also discuss several other topics like How many electrons are transferred in redox reaction?

■ Follicle grows, then levels drop @ ovulation

■ Cells switch to produce progesterone

○ *when labeling take the time to write “ovulation” at day 0 and 20* ● Luteal Phase: area where progesterone is high (between ovulations) ○ Dog luteal phase lasts 5-7 months

○ Because it is longer than gestation no need for embryo to send “signal” ■ Progesterone constantly high during long period

● Feedback in Female Reproduction:

○ Feedback is negative or positive depending on time

Don't forget about the age old question of Does whistleblowing need justification?

● Stress / Parturition:

○ “Triggered” by release of cortisol from fetus

○ → increased release of estrogen by placenta

○ → estrogen causes uterus to start contracting

○ Uterus releases prostaglandins which cause regression of CL

■ → drop in progesterone

○ Progesterone inhibits the contractions of uterus If you want to learn more check out What is a population in statistics?

■ → drop in progesterone = stimulates contractions

○ Oxytocin = posterior pituitary hormone

■ Stimulates contraction + mammary production

■ Makes other systems “forget” about pregnancy


● Mature Ovary (turkey):

○ Follicle labeled in order of “readiness” to release egg

○ Looks different because they ovulate once a day

○ Egg has to carry all nutrients for embryo development

○ Stigma = area on follicle that’s not vascularized (no blood vessels) ■ Where the follicle ruptures to release egg (to prevent blood loss) ■ LH causes this rupture

Don't forget about the age old question of What does second-degree murder mean?

● Anatomy of Female Bird Reproduction:

○ Magnum - lays down nutrients

○ Isthmus - lays down membranes

○ Shell gland - lays down calcified shell

○ Sperm storage tubules - hold sperm to release later ■ Can hold for up to 2 weeks

● Ovulation:

○ Release of LH causes enzymatic “digestion” of stigma ○ Follicle ruptures → release of egg = start of ovulation ○ Smooth muscles in the theca externa contract

○ Granulosa cells remain metabolically active for 24-48 hours ■ Producing progesterone and prostaglandins

○ *very dependent upon light*

● Oogenesis:

○ Primordial germ cell differentiates into oogonium

○ Oogonium enters meiosis

○ Primary oocyte = 2N, 4C → has replicated DNA

○ Arrested development 

■ Essentially stops at metaphase 1 of meiosis

○ LH activates meiotic “machinery”

○ 1st metabolic division is very uneven (at ovulation, 1N, 2C) ○ If fertilized then second division occurs

■ 1N, 1C

■ Restores diploid state with sperm DNA added

■ Why do we “throw away” 3 copies of DNA? (unlike males)

● Allows for cell to be big and retain almost all cellulose and nutrients, DNA is all that’s wasted

● Maximizes cell survival

● Arrested development + uneven division

○ Differentiate oogenesis from spermatogenesis

● Fertilization:

○ Homunculus - little man inside sperm

○ Physical union of male and female gametes (sperm and ova) ● After fertilization egg divides and develops

● Embryo stage = ​no longer reliant on maternal RNA, produce own

○ Zygote - one celled embryo

● Early Development:

○ From conception to death:

○ Embryonic: from fertilization until all essential organs are formed ○ Fetal: end of embryonic stage until parturition

○ Gestation length: varies (don’t need to memorize lengths)

● E = morula stage (inner cell mass)

● F = blastocyst stage (fluid filled space = blastocele)


● A = zygote

● B = 2 cell

● C = 4 cell

● E = morula, still held together by zona pellucida

● F = 72 hours after fertilization

○ Dark clump of cells is what actually becomes fetus (Inner Cell Mass) ○ Mass eventually “hatches” out of zona pellucida

● Definitions:

○ Blastocyst: a hollow sphere of cells composed of two cell layers (the trophoblast) with a clump of cells inside (the ICM or inner cell mass) ○ Blastocoele: fluid filled interior of blastocyst

○ Trophoblast: cells form the extraembryonic membranes

● In ruminants, embryo turns into a worm-like thing

● Extra-embryonic membranes:

○ Provide protection for embryo - fetus and nutrient / waste exchange ○ Amnion: fluid filled sac like airbag around embryo

○ Yolk sac: stores yolk (essentially empty in mammals)

○ Chorion and Allantois: (often fused)

■ Chorion = outer layer contributing to placenta

■ Allantois = outgrowth of bladder for nutrient/waste exchange, respiration, and storage of urine

● Recognition of Pregnancy:

○ Primates: (aka humans)

■ Blastocysts secrete chorionic gonadotropin (CG)

■ CG binds to LH receptors in the CL and stimulates continued secretion of progesterone

○ Ruminants:

■ Not Pregnant: CL regresses at end of cycle

● Due to endometrial secreting PGF

■ Pregnant:

● (bovine) embryo secretes interferon tau which decrease

PGF secretion

● (sheep) embryo secretes ovine trophoblast protein which inhibits production of PGF

○ Pigs:

■ Release estradiol to block PGF

■ Minimum 3-4 embryos

○ Dogs: monoestrous (basically keep secreting progesterone anyway) ● Gestation: differs by species DON’T MEMORIZE THE NUMBERS ● To know for Midterm 1:

○ Structures and functions

○ Oogenesis

○ Hormones, site of synthesis, target organ (or cell), and function ○ Stages of early development

● Manipulating Reproduction:

● Males:

○ Artificial Insemination: 

■ Depends on ability to collect semen and cryopreservation (pig semen can’t be stored like other animals’)

■ Used in: broad breasted turkeys, cattle, sheep, horses, dogs

■ Also for captive / endangered species preservation

○ IntraCytoplasmic Sperm Injection: 

■ In Vitro Fertilization: inject single sperm + shock egg into thinking fertile (most widely used in humans)

● For infertility

● Preservation of genetics

■ Controversy: may pass on infertility if genetic

● Females:

○ Estrous Synchronization: (so all can be inseminated at once) ■ Ruminants:

● Melengestrol Acetate (MGA) - orally administered, acts like progesterone

● CIDRs - controlled internal drug release

○ 10% progesterone by weight

● GnRH + PGF

■ Pigs:

● PG600 - pregnant mare serum gonadotropin (PMSG) and

human chorionic gonadotropin (HCG) - induces fertile heat

○ Superovulation: 

■ Artificially induced ovulation of more oocytes than normal for species

■ 2 methods:

● Intramuscular injection of PMSG + luteolytic dose of PGF

● 8-10 injections of FSH at half-day intervals

○ Best to synchronize ovulation (shot of GnRH) slims

down time frame by hours

○ In Vitro Fertilization: 

■ Oocytes collected from ovaries after slaughter or ovum pick up following superovulation

■ Matured and fertilized in vitro

■ Embryos transferred immediately or following culture

○ Ovum Pickup: (OPU)

■ Ultrasound guided - noninvasive - aspiration inside the cow ■ Highly repeatable

○ Induced Abortion: 

■ PGF - causes CL breakdown

■ Dopamine agonists - decline of prolactin in dogs

○ Frozen Zoo: sperm, embryo, cells, ovaries

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