Introduction to Theriogenology Flashcards
What are oviparous animals?
- Egg laying
- Ovum surrounded by large amount of yolk
- +/- internal fertilization
- Birds, fishes, amphibians
What are Ovoviparous aniimals?
- Egg (non-placental) incubation with birth of live young
- Have egg with protective shell
- Internal fertilization and internal hatching
- Most reptiles
What are viviparous animals?
- Placental gestation with birth of live young
- Mammals - suckle young
What are Monotremes?
Mammals that lay eggs and suckle young (platypus)
What is the location and function of Ovaries?
- Caudal to the kidneys - suspended from the body wall by part of the broad ligament (“suspensory ligament”
- Secrete gametes via tubular genitalia (uterine tube + uterus)
- Produce hormones (estradiol and progesterone)
What are the important structures of the Ovary? function?
- Peripheral parenchyma (cortex) - contains various stages of follicular and luteal gland development (most species)
- Central Vascular zone (medulla) - contains connective tissue rich in blood vessels (most species)
-
Follicles - enclose oocyte, become fluid-filled, estradiol (and others) become concentrated in follicular fluid.
- palpable in bovine at > 6-10mm diameter
- Corpora lutea - after ovulation (or lutenization w/o ovulation), the cells of the follicle become corpora luteal cells
What are the important structures of the Ovary? function?
- Peripheral parenchyma (cortex) - contains various stages of follicular and luteal gland development (most species)
- Central Vascular zone (medulla) - contains connective tissue rich in blood vessels (most species)
-
Follicles - enclose oocyte, become fluid-filled, estradiol (and others) become concentrated in follicular fluid.
- palpable in bovine at > 6-10mm diameter
- Corpora lutea - after ovulation (or lutenization w/o ovulation), the cells of the follicle become corpora luteal cells
Where is the bovine Ovary located? palpable structures?
- Readily palpated
- Suspended from the broad ligament cranial or cranial-lateral to the tip of the uterine horns
- Palpable structures:
- Tertiary follicles (possess fluid-filled antrum)
- Corpora Lutea (CL)
- Corpora haemoragicum (not always able to ID)
- Corporal albicans (regressing CLs)
What does the Equine Ovary look like? palpable structures?
- Bean shaped
- Not as freely moveable as bovine
- Ventral border is concave (ovulation fossa)
- Peripheral area is vascular connective tissue and central parenchyma has follicular and luteal gland tissue (inside out)
- Palpable structures:
- Follicles located in the ovulation fossa
- Corpora lutea are NOT palpable
What are the parts of the Uterine tubes? functions?
- Fimbria - cilia sweep the ovum from the ovary at ovulation into the infundibulum
-
Infundibulum -⅓ portion of the uterine tube nearest the ovary
- funnel-like, catches the ovum at ovulation
-
Ampulla - middle third of the uterine tube
- sight of fertilization
-
Isthmus - Portion of uterine tube closest to uterus
- Uterotubal junction (UTJ) in the equine acts as a mechanical barrier to the passage of the early (
what is the structure and function of the Uterine Horns?
- Formed from the paired Mullerian Ducts
- Lined with a vascular and glandular mucosa and contain smooth muscle
- Endocrine (hormone producing) organ
how is the Uterus formed?
- Stars as 2 long tubes (Mullerian ducts)
- Degree of fusion of the ducts varies by species
What is a Unilateral tract?
- Only the left Mullerian duct forms into a functional oviduct/uterus
- Birds
What is a Marsupial uterine tract?
- Mullerian ducts fuse very distally (near vulva) therfore, have 2 vaginas and 2 cervix
- Opossum, Kangaroo, Koala, etc
- Male opossum have forked penis - so do sugar gliders
What is a Duplex uterine tract?
- Mullerian ducts fuse very distally
- 1 vagina and 1 or 2 cervix
- No migration of embryos between horns
- Most Rodents
What is a Bicornuate uterine tract?
- 2 long horns
- Mullerian ducts fuse cranial to cervix (short uterine body)
- Easy migration of embryos between horns
- Porcine, Canine
What is a Bipartate uterine tract
- Two horns with distinct septum
- Mullerian ducts fuse cranial to cervix - short uterine body
- Seldom have migration of embryos between horns
- Bovine, Ovine
What is a Modified Bipartate Uterine Tract?
- 2 horns
- long uterine body - as long as horns
- Equine
What is a simplex uterine tract
- Mullerian ducts completely fused - no horns (only uterine body)
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What are some common uterine abnormalities?
- Cows - 2 cervixes
- Humans - Bicornuate uterus (instead of simplex)
What is the cervix and its function?
- Connective tissue and muscle forms tube-like sphincter
- Almost always “closed” - acts as a barrier to protect uterus
What is special about the equine cervix?
- No cartilage
- Changes tone during estrus cycle
- based on concentrations of progesterone and estradiol
What is the vagina and its function?
- Caudal to uterus/cervix - located in the pelvic canal
- Where sperm is deposited in many species
- Very long in the canine
How many layers are in the placenta? what are they?
- up to 6 layers of tissue
- Maternal tissues:
- Blood vessel endothelium
- connective tissues (syndesmo layer)
- Epithelium of endometrium
- Fetal tissues:
- Chorion
- Connective tissue
- Blood vessel endothelium
- Maternal tissues:
What is epithelial Chorial placentas? which animals have this type of placenta?
- Maternal epithelium of the endometrium is in contact with the fetal chorion
- (no erosion of the epithelium)
- All 6 layers of tissue are intact throughout pregnancy
- Sow, Mare
- Cattle, sheep
- modified - AKA Syndesmo-chorial
- not as much intact epithelium as the sow and are
What is a Endothelial-chorial placenta? which animals have these?
- Maternal blood vessel endothelium is in contact with fetal chorion
- i.e. uterine epithelium is eroded over sites of contact with the chorion)
- 2 layers of tissue (epithelium and connective tissue of endometrium) have been removed at fetal-maternal contact sites
- Dogs, cats, others
What is a Hemochorial placenta? What animals have these?
- Maternal blood is in direct contact with the fetal chorion
- 3 layers of tissue (epithelium and connective tissue of the endometrium as well as the blood vessel endothelium ) have been removed at fetal-maternal contact sites
- Mice, rates, primates, guinea pig
What type of chorionic villous pattern do pigs have?
diffuse
What chorionic villous pattern do equines have?
diffuse and micro-cotyledonary
What is a Cotyledonary Placenta? Which animals have these?
- Have a Placentome
- Caruncle (maternal)
- Cotyledon (fetal)
- Cow, Sheep
What is a Zonary placenta? which animals have these?
- a
- Dogs, Cats
What is a discoid placenta? which animals have this type of placenta?
- a
- Primates, rodents
What are the differences in male reproductive tracts between a Bull, Stallion, Boar, Dog, Tom?
What is the purpose of the penis?
- Copulatory organ
- Deposits semen (sperm cells + accessory gland fluid) into vagina or cervix/uterus (species dependent)
What are the different types of penis?
- Fibroelastic penis - minimal erectile tissue
- ruminants
- Vascular penis - a lot of tissue that responsds to sexual stimulus by pooling blood w/in spongy spaces leading to erection
- Equine
- Boney penis - Os penis - only achieve erection after intromission
- Canine, Feline
What are the parts of the male reproductive tract? what are their functions?
- Testicles and secondary sex organs
- epididymis, vas deferens, and penis - transport sperm from the testicle to the female reproductive tract
- Ampulla is a dilation of the vas deferens that pools sperm during ejaculation
- 3 accessory sex glands - seminal vesicles, prostate, bulbourethral gland provide fluid for semen
- Testicles - produce spermatozoa & testosterone
- epididymis, vas deferens, and penis - transport sperm from the testicle to the female reproductive tract
Where are the testes located? Why?
- In many mammal - outside of the body cavity in the scrotum
- essential for normal sperm formation which occurs at a temperature below normal body temp
- In birds - intra-abdominal and held at body temperature
- sperm survives longer in female tract
- Chickens only need to make once a week (turkeys every 2)
What is the pampiniform plexus?
- Found in the neck of the scrotum
- complex venous network that surrounds the testicular artery and functions as a countercurrent heat exchanger to reduce testicular temperature
- important for thermoregulation
How does the scrotum protect the testicles from extreme temperatures?
- contains a temperature sensitive layer of muscle (tunic dartos) under the skin of the scrotum
- relaxes when hot
- contracts when cold
How does the Cremaster muscle help protect the testicles against temperature extremes?
- when relaxed - testicles are ‘dropped’ increasing the relative length of the scrotum - move the testicles away from body heat
- In cold weather - Cremaster contracts and the testicles are pulled closer the the warm body
What is the structure of the Seminiferous tubules?
- Many hundreds of individual seminiferous tubules in the testicle
- they unite with one another until approximately a dozen tubules pass out the testicle into the head of the epididymis.
- Made up of Sertoli cells and layers of germ cells
