بسم الله الرحمن بسم الله الرحمن الرحيمالرحيم

ورحمته ورحمته السالُم� َع�ليڪم السالُم� َع�ليڪم اللهالله

Under Kind Supervision Under Kind Supervision

Dr. K.B. MirbaharDr. K.B. MirbaharProfessor Professor

Department of Animal ReproductionDepartment of Animal Reproduction

By:Sajid Aziz Samo

2K8-AR-156

ESTRUS CYCLEThe recurrent, restricted period of sexual receptivity in female mammals,

Marked by intense sexual urge.

Or

The female reproductive system of most mammals exhibits a rhythmical changes called the estrus cycle.

To understand the different parts of the estrous cycle.

To understand the hormonal changes during the estrous cycle.

To understand how the estrous cycle coordinates the events of

female reproduction so it can be successful.

LEARNING OBJECTIVES

Proestrus: ( Period Of Preparation ) Characterized by stimulation of follicular growth by FSH

Estrus: ( The Period Of Desire ) Characterized by psychic manifestations of heat

Metestrus: ( Postestrus ) Characterized by the sudden cessation of heat

Diestrus: ( The Final Period )

PERIODS OF THE ESTRUS CYCLE

ANESTRUS:

Female is not cycling (No expression of heat over time)

Cow has a 21 Day Estrous Cycle: Day 0 first Day of Standing Heat

Tertiary follicle(s) and oocytes undergo final maturation Estrogen levels

Female starts to become receptive - Estrogen prepares uterus and oviducts for sperm transport and fertilization - Estrogen initiates uterine changes for later embryo development

(Day 17-20 (Follicular Phase)

Prior to estrus, CL is undergoing regression, progesteronelevels fall below 1 ng/mL which allows final follicular development

One dominant follicle - Graafian StageStimulated to final maturation by FSH and LH

Estrogen

Smooth muscle contractions and cilia movement

Uterine glands and oviduct secretion

PROESTRUS:

CYCLIC CHANGES IN OVARIAN CYCLIC CHANGES IN OVARIAN STRUCTURESTRUCTURE

PROESTRUS

( Day of Standing heat! Day 0 of estrous cycle Lasts 12 to 20 hours in cow)

Estrogen from the Graafian follicle stimulate increase in GnRHwhich stimulates increase in LH

GnRH increases to cause a large increase in LH (surge release) Ovulation occurs during estrus in ewe, sow and mare but

metestrus in cow

Following ovulation - LH stimulates development of luteal cellsfrom the granulosa and thecal cells of the ovulated follicle wall.

Theca and granulosa cells luteinize by LH stimulation to differentiate in luteal cells

ESTRUS:FEMALE IN HEAT

High estrogens cause LH surge

LH surge causes ovulation

LH surge initiates corpus luteum formation

SIGNS OF ESTRUS PERIOD

1. Restlessness

2. Mounting

3. Swollen vulva

4. Bawling

5. Discharge of the watery mucosa

ESTRUS

Estrogen levels have decreased

Corpus luteum is forming

Progesterone levels start to

Progesterone begins preparing the uterus for the embryo Embryo partially develops in the oviduct and moves into the uterus

(Day 2-4 of Estrous Cycle)

In cow, ovulation occurs after the end of estrus

Graafian follicle has ovulated

Developing from Corpus Hemorrhagicum

Second increase in FSH occurs to stimulate anotherwave of follicular development

Moves into uterus on Day 4 - 5 depending on species

METESTRUS:

Maximum corpus luteum size High progesterone levels inhibit final follicular development, ovulation and estrus

Embryo continues to develop in the uterus Embryo signals the uterus it is present - no CL regression If embryo is not present - uterus releases PGF2a to cause CL regression If CL regresses, progesterone in blood decreases and Graafian follicle(s) begin final development that occurs in proestrus for ovulation at estrus.

(Day 5 - 17 of Estrous Cycle)

Mature at Day 12 of estrous cycle

Inhibits final maturation of follicle and estrus Negative feedback on GnRH

Estrous Cycle starts over!!!!

DIESTRUS:

HORMONAL PROFILES DURING THE ESTROUS CYCLE

ng = nanogram 10-9 grams LH, FSH, Progesteronepg = picogram 10-12 grams Estrogen, PGF2a

Follicle will become atretic and regress as a new follicle grows to ovulate with CL regression

Increases for CLregression Second increase of FSH for

follicle development. Inhibinis low as is progesterone

When progesterone is less than 1 ng/ml it usually means the cowhas regressed the CLand is coming into heatduring the estrous cycle

Estrus

LH surgefor ovulation

First FollicularWave

Second FollicularWave

Estrus ESTRUS

MARE

PHASES OF THE ESTROUS CYCLE

FOLLICULAR: (from the regression of CL to ovulation) 2-3 days in ewe and 3-4 days in cow

LUTEAL: (period of corpus luteum activity)

Phase of the female estrous cycle when she is underestrogen stimulation

Proestrus and Estrus

Phase of the female estrous cycle when she is underprogesterone stimulation

Metestrus and Diestrus

CYCLIC CHANGES IN VAGINAL CYCLIC CHANGES IN VAGINAL CELL TYPESCELL TYPES

Estrus Diestrus I Diestrus II Proestrus

SPECIES VARIATION IN ESTROUS CYCLE CHARACTERISTICS

ESTROUS CYCLE EWE SOW COW MARE

LENGTH OF ESTROUS CYCLE

14 - 19 DAYS

18 - 22 DAYS

18 - 24 DAYS

16 - 24 DAYS

LENGTH OF ESTRUS

24 - 36 HOURS

48 - 72 HOURS

12 - 19 HOURS

2 - 11 DAYS

TIME OF OVULATION

24 - 36 HOURS AFTER THE ONSET OF ESTRUS

35 - 45 HOURS AFTER THE ONSET OF ESTRUS

10 - 11 HOURS AFTER THE END OF ESTRUS

1 - 2 DAYS BEFORE THE END OF ESTRUS

TIME OF AI

12 - 18 HOURS AFTER THE ONSET OF ESTRUS

16 - 14 HOURS AFTER THE ONSET OF ESTRUS AND AGAIN 8 - 24 HOURS LATER

7 - 18 HOURS AFTER ONSET OF ESTRUS

SECOND DAY AND EVERY OTHER DAY IN ESTRUS

PRESENTED BY.PRESENTED BY.

SAJID AZIZ SAMOSAJID AZIZ SAMOREG. NO. 2K8-AR-156REG. NO. 2K8-AR-156