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CHAPTER 2. ANATOMY & PHYSIOLOGY OF REPRODUCTION. Anatomy. The Structural Make-up of the Reproductive System. Female Reproductive Tract Location. Female Reproductive Tract Location. Female Reproductive Tract. Vulva. Vulva. Vulva. Vulva. Entrance to the Reproductive tract
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CHAPTER 2 ANATOMY & PHYSIOLOGY OF REPRODUCTION
Anatomy • The Structural Make-up of the Reproductive System
Vulva Vulva
Vulva • Entrance to the Reproductive tract • Below the intestinal tract entrance • Beneath the tail • Continued forward by the Vagina
Vagina Vagina
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
Cervix Cervix
Cervix • Most Important Part of Reproductive Tract For Insemination • Thick-walled Tube with Irregular Passageway • Valve Between Delicate Inside Organs and Tougher Outer Organs
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
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
Cervix Location • Usually Found at Cow’s 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
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
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
Uterus Uterus
Uterine horn Uterine horn Bovine Reproductive Tract
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
Oviducts Oviducts
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
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
Ovarian Structures • Graafian Follicle • Corpus Luteum
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
Physiology of Reproduction • Functions of the various parts of the reproductive system
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
Estrogen • Circulates Throughout the Body • Production is Greatest When Follicle Reaches its Largest Size • Causes Changes in the Cow
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
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
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 Calf’s Presence In Uterus Causes Yellow Body to Remain Active • Alternating Dominance of Follicle/Estrogen and Yellow Body/Progesterone = Estrous Cycle
Progesterone • Stops Follicle/Egg Production • Prepares Uterus for Fertilized Egg
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