ANATOMY

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CHAPTER 2

• ANATOMY PHYSIOLOGY OF REPRODUCTION

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Anatomy

• The Structural Make-up of the Reproductive System

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Female Reproductive Tract Location
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Female Reproductive Tract Location
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Female Reproductive Tract
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Vulva
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Vulva
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Vulva

• Entrance to the Reproductive tract
• Below the intestinal tract entrance
• Beneath the tail
• Continued forward by the Vagina

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Vagina
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Vagina

• 8 to 12 Inches in Length
• Strong Thick-Walled
• Usually a Collapse Tube
• When Collapsed Folds Run Lengthwise
• Normally Unobstructed
• When Shortened Folds are Similar to Accordion

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Bovine Reproductive Tract
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Cervix
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Cervix

• Most Important Part of Reproductive Tract For
  Insemination
• Thick-walled Tube with Irregular Passageway
• Valve Between Delicate Inside Organs and Tougher
  Outer Organs

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Cervix

• Feels Like a Chicken Neck
• Firm and Dense to Touch, Gristly Feeling
• 2 to 4 1/2 Inches in Length 3/4 to 2 Inch
  Diameter

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Cervix

• 2 to 4 1/2 inches long
• Longer in Brahman Derivative Cattle
• Cows 3/4 to 2 inches in Diameter
• Heifers 1/4 to 1/2 inches in Diameter
• Size and Consistency Change With Age and
  Pregnancy
• Late in Pregnancy Softer and Larger
• Postpartum Much Larger and Very Soft

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Cervix Location

• Usually Found at Cows Midline on Front Edge of
  Pelvic Floor (Brim)
• In Aging Cows May be Well Forward of Pelvic Brim
• During Pregnancy Cervix Tends to be Forward and
  Downward Beyond the Pelvic Brim
• Cows and Heifers That are Straining Cause the
  Cervix to be Toward the Rear End of the Bony
  Pelvis

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Cervix Location
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Normal Cervix
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Aging or Pregnant Cow Cervix
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Beware of Obstacles

• Blind Pouch
• Front End of Vagina
• 1/2 to 1 Inch Deep, Surrounds Entire Back of
  Cervix
• Fingerlike Projections
• Arranged in 3 or 4 Circular Rings
• Cause Passageway to be Crooked, Contain Blind
  Pockets, or Dead Ends

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Natural Obstructions
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Bovine Reproductive Tract
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The Target

• Semen Should be Deposited Into the Uterine Body

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The Target
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Uterus

• Womb Where Calf Develops
• Single Short Body and Two Horns
• Horns Vary in Length From 8 to 15 Inches, and 5/8
  to 2 Inches in Diameter
• Walls of Uterus are Soft and Spongy
• Avoid Passing Syringe Past the Front End of
  Cervix
• It is Easy to Poke Into or Through the Uterine
  Wall
• Can Cause Infection or Even Fatal Peritonitis

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Uterus
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Bovine Reproductive Tract
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Uterus
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Oviducts

• Also Known as Fallopian Tube
• 8 to 10 Inches Long
• Outside Diameter is Size of a Pencil Lead
• Inside Diameter is Microscopic
• Tube That Provides Route Between Ovary and
  Uterine Horn
• Sperm and Eggs Move Through These Tubes
• Fertilization Occurs Halfway Down Oviduct
• Site Called Ampullary-Isthmic Junction

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Oviducts
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Bovine Ovary
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Ovaries

• Oval-Shaped
• 1 to 2 Inches Long
• Two Per Cow
• Left and Right
• Produce Tiny Eggs (ovulate)
• Right Ovary Releases Slightly More Than 1/2 of
  the Eggs
• Chance Determines Which Ovary Will Produce Egg at
  Ovulation

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Structures in the Ovary

• Graafian Follicle
• Fluid Filled Sac Where Egg Develops
• Fluid is Rich in Hormones
• Bring About Temporary Physical and Psychological
  Changes
• At a Certain Time the Follicle Ruptures
• Corpus Luteum (CL)
• Also known as the Yellow Body
• Develops at Site of Collapsed Follicle
• Rapid Growing, Solid, Meaty Structure
• Remains Throughout Pregnancy

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Ovarian Structures

• Graafian Follicle Corpus Luteum

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Corpus Luteum
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Rectum
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Rectum

• Thin-walled Tube
• 10 o 12 Inches Long and Stretchable
• Manipulate Cervix Through It
• Anus is Valve Between Rectum and Outside
• Made up of Circular Muscle Under the Skin
• Stretchable - Hand and Arm Enter Easily
• Circular Contractions Move Along Rectal Wall
  Toward the Outside
• When Strong They can Make Manipulation Difficult

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Physiology of Reproduction

• Functions of the various parts of the
  reproductive system

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Follicle
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Role of the Follicle

• Pituitary Gland Hormone Stimulates Egg Growth
• Follicle-Stimulating Hormone (F.S.H.)
• Many Follicles Recruited For Development
• One Selected To Become Graafian Follicle
• Follicle Grows Larger Secretes More Estrogen
• Affects the Nervous System Causes Restlessness
• Causes Cow to Stand for Mounting
• Prompts Uterus Contractions
• Increases Blood Flow to Genital Organs

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Estrogen

• Circulates Throughout the Body
• Production is Greatest When Follicle Reaches its
  Largest Size
• Causes Changes in the Cow

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Signs of Heat

• Stands for Mounting by Other Cows
• Stands and Accepts Service From Bull
• Vulva Swells
• Mucus is Discharged
• Cow is Nervous and Restless

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Graafian Follicle
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Corpus Luteum
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Role of the Yellow Body

• Luteinizing Hormone (L.H.)
• Causes Follicle to Undergo Changes to Release Egg
• About 10 to 14 Hours After Heat Ends
• Follicle Ruptures and Ovulation Occurs
• Egg Released
• Cells Inside Collapsed Follicle Grow
• Forms Yellow Body or Corpus Luteum
• Secretes Pregnancy Hormone - Progesterone
• Prepare Uterus to Accept Fertilized Egg
• Maintains Pregnancy by Preventing Heat Cycles

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Role of the Yellow Body

• If Egg is Not Fertilized
• Corpus Luteum Stops Producing Progesterone 16
  Days After Heat
• Reduction of Progesterone Allows New Follicle and
  Egg Development and New Heat at 21 Days
• If Egg is Fertilized and Accepted
• Developing Calfs Presence In Uterus Causes
  Yellow Body to Remain Active
• Alternating Dominance of Follicle/Estrogen and
  Yellow Body/Progesterone Estrous Cycle

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Progesterone

• Stops Follicle/Egg Production
• Prepares Uterus for Fertilized Egg

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Summary of Female Reproductive Hormones
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Other Reproductive Activity

• Sperm Waits in Oviducts
• Sperm Travels from the Cervix in 2 1/2 Minutes
• Sperm Requires Time in Female Reproductive System
  Before Capable of Fertilization
• Special Chemicals in Female Tract Aid Sperm
  Maturity
• Uterus Lining Changes
• Thickens to Support and Sustain Fertilized Egg
• Bloody Mucus 2 to 4 Day After Heat
• Does Not Signal Pregnancy or No Pregnancy
• Signals Cow Was in Heat a Couple Days Ago

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• Sperm Produced in Testicles
• Sperm Accumulate and Mature in Epididymides
• Sperm Pass on to Larger Collection Tube in Vas
  Deferens
• Urethra Provides Canal for discharge
• Sperm Discharged During Ejaculation
• 63 Days are Required For Sperm Production to
  Ejaculation

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Breeding

• Natural Service
• Bull Ejaculate Semen Deeply in Cows Vagina
• Deposits 4-6 Billion Sperm Cells
• Artificial Insemination
• Semen Deposited in Body of Uterus
• Sperm is Carried Through Uterus to Oviducts
• Fertilization Single Sperm Penetrates Egg
• 3 to 5 Days Later Fertilized Egg Reaches Uterus
• Initial Cell Divisions Have Taken Place

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Pregnancy

• By Week 4 Fetal Membranes Line Uterus
• Stretch From Right to Left Uterine Horn Tips
• Developing Calf/Embryo Grow in Membrane
• Later Cotyledons Form
• Attachment Between Membrane and Uterine Lining
• Form in About 100 Specific Sites
• Provide Nutrients for Developing Calf From Dams
  Blood
• Transfer Waste From Calfs Blood to Dams Blood
• Gestation Normally Lasts 280 Days (9 Months)

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Birth

• Calf Initiates Complex Birth Process
• Cervix Relaxes Under Hormonal Influence
• Uterus Contracts
• Forces Fetal Fluids in Fetal Membranes to Open
  Cervix
• Membranes and Calf Enter and Stretch Vagina
• Contractions of Abdominal Wall and Diaphragm
  Muscles With Uterine Contractions Rupture Fetal
  Membranes
• Fetal Fluids are Discharged
• Calf is Forced Through Remainder of Birth Canal
• Fetal Membranes Discharged 1/2 to 8 Hours Later
• Uterus Gradually Contracts and Repairs Itself

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Ideal Calf Position At Birth
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Summary
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Re-breeding Fertility Levels
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Voluntary Waiting Period (VWP)

• 45 to 50 Days Needed to Repair Uterus
• Must Shrink From Sack that Held
• 80 to 100 Pound Calf
• 5 to 8 Gallons of Fluid
• 10 Pounds of Afterbirth
• To a Small 1 to 2 Pound Organ the Size of a Pair
  of Mans Fists

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Postpartum Uterus
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Placentomes

• 100 Distinct Button-Like Sites Attach the Fetal
  Membranes to Lining of the Uterus
• Carancules are Located on the Uterine Lining
• Cotyledons are Located on the Fetal Membrane
• Each Carancule is Covered by a Cotyledon
• Makes up a Structure Called the Placentome
• At Calving Some Will Reach 3 by 5 by 2 Inches
• For Normal Discharge of Fetal Membranes,
  Cotyledons and Carancules Must Promptly Separate

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Placentome
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Nutrient Exchange

• Placentome
• No Mixing of Blood, But Transfers Nutrient
  Waste
• Nutrients Dissolved in Cows Blood Pass Through
  Thin Membrane Into Calfs Blood
• Waste Products From Calf Transfer Through Same
  Membrane Into Cows Blood for Elimination
• Mass of Tiny Blood Vessels
• Separated by Thin Tissue Layers
• Permit High Volume of Blood Flow
• Enables Easy Exchange of Nutrients and Waste

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Recovery Delays

• Considering Size and Function of Tissues
• Takes Considerable Time to Return to Normal
  Condition
• Return to Normal Condition Delays Include
• Calving Difficulties
• Uterine Diseases at Calving
• Retained Fetal Membranes
• Other Uterine Infections
• Some Diseases Within the Cow

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10 Days After Calving

• Horns are Very Relaxed
• Uterine Cavity Still Large
• Caruncles Still an Inch Long
• Uterine Cavity Contains Bloody Fluid

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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17 Days After Calving Twins

• Uterus Retained Fetal Membranes
• Walls are Very Thick
• Contains Bloody Pus
• Caruncles Have Not Reduced Size
• Without Treatment Will Not be Ready for Breeding
  at 45 Days
• Untreated Infection Could Spread to Fallopian
  Tubes Causing Blockages

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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20 Days After Calving

• Uterus Filled With Pus
• Caruncles Large and Discolored

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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50 Days After Calf Aborted

• Recovery Was Rapid
• Generally if Abortion Occurs After 3 Months
  Should Give Cow a 50-day Rest
• If Obvious/Severe Uterine Infection Follows
  Abortion, Get Veterinary Treatment, Needed Rest
  Time May Be Longer

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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28 Days After Calving

• Free From Obvious Pus and Dead Blood
• Caruncles are Still Enlarged and Swollen

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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35 Days After Calving

• Caruncles are Still Large
• A Little Pus and Some Inflammation of Uterus
  Lining

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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50 Days After Calving

• Uterus is Ready for Rebreeding
• Fully Contracted
• Free From Inflammation
• Caruncles are Small, Almost Level Spots

Photo Courtesy of Dr. N.L. UanDemark, Cornell
University
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Summary

• Cervix Can Be Manipulated Through the Rectal Wall
• The Vagina Provides Passage to the Cervix
• Cervix is Generally Located on the Front Edge of
  the Pelvic Floor
• The Target for Depositing Semen is the Uterine
  Body
• Uterus is Where Embryo Grows Into Calf

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Summary

• Uterus Consists of Three Parts
• Small Body and Two Horns
• Extending From Uterine Horns are Fallopian Tubes
• At end of Fallopian Tubes are Ovaries
• Every 21 Days Ovaries Produce Egg
• Egg Develops Within Graafian Follicle
• As Follicle Grows it Secretes Estrogen

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Summary

• 10 to 14 Hours After Heat Ends, Egg is Ovulated
• Collapsed Follicle Grows Into Corpus Luteum
• Corpus Luteum Produces Progesterone
• Progesterone Stops Follicle and Egg Development
• Gestation for a Calf is About 280 Days
• A 45-Day Rest Between Breedings is Required for
  Reasonable Conception Rates

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Question 1

• Trace the female reproductive tract. Name the
  organs involved as you follow the tract, starting
  outside the animal.

Vulva, Vagina, Cervix, Body of Uterus, Uterine
horns, Oviducts, and Ovaries
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Question 2

• When youre doing A.I., the cervix is the most
  important part of the female. How can you tell
  for sure where the cervix begins and ends?

The cervix tissue feels like a chicken or turkey
neck. The vagina feels soft and elastic. The
uterus is soft spongy like tissue.
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Question 3

• To achieve the highest fertility rate, where
  should you deposit semen?
• By what other name is this area sometimes called?

The body of the uterus.
The inseminators target.
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Question 4

• Eggs are produced in the ovaries. Do both
  ovaries release eggs in each estrual cycle?

No only one. Chance determines which one will
produce the egg.
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Question 5

• What are two function of the follicle?

To produce the egg by producing FSH, and to
produce estrogen.
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Question 6

• Describe how the hormone estrogen affects females.

Estrogen causes the female to become restless and
to stand to be mounted by another animal. It
also increases blood flow to the uterus and
causes glands in the vagina and at the cervix to
produce mucus.
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Question 7

• How frequently can you expect healthy,
  non-pregnant heifers and cows to come into heat?
• How long does standing heat last?

Approximately every 21 days.
Between 6 and 30 hours with an average of 18
hours.
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Question 8

• What are two function of the yellow body?

Replace the follicle, and secrete progesterone to
prepare the uterus for pregnancy and prevent heat.
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Question 9

• Explain how progesterone affects the female?

Progesterone helps to prepare the uterus for
accepting the fertilized egg by reducing uterine
muscle contractions and promoting development of
the uterine lining. It also helps maintain
pregnancy by preventing heat cycles.
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Question 10

• How soon after heat ends does ovulation , or egg
  release, occur?

Between 10 and 14 hour, but it can range from 6
to 18 hours.
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Question 11

• After youve properly deposited semen, how long
  does it take sperm to reach the end of the
  oviduct where fertilization can occur?
• Can sperm immediately fertilize the egg if it is
  available?

Approximately two and a half minutes.
No, it must mature in the oviduct first.