Lecture Terms Flashcards
axial skeleton
vertebral column, skull, ribs, sternum
appendicular skeleton
long limbs, pelvic and pectoral girdle
flexion angle
depends on functionality - flexing a muscle will happen if the flexor angle is DECREASED
cranial/caudal above the hock or manus
palmar/plantar/dorsal beneath it
Five recognized radiodensities
From radiolucent to radiopaque:
Air, Fat/Oil, Water/Soft Tissue, Bone, and Metal
Orthogonal angle
A perpendicular angle, necessary to get 3d information from two 2d images
Why are shoulder and scapula fx and luxations relatively uncommon?
Scapula is held close to the body and has a great deal of muscle padding. The shoulder has a very large articular surface - it is hard for it to get displaced.
Why are humeral and rad/ulna fx common?
Far from the body and more exposed
Meant to bear weight cranially/caudally not orthogonally.
Is luxation of the elbow usually medial or lateral?
Lateral. The capitulum and the lateral epicondyle of the humerus are both smaller than their medial counterparts.
How should luxation of the elbow be reset?
With the elbow flexed. The olecranon will be in the way otherwise.
luteinizing hormone (LH)
Hormone that surges 24 hours prior to ovulation. Causes the maturation the follicle/oocyte.
What is the progression of the maturation of the oocyte in the ovary?
Primordial follicle Secondary follicle Mature follicle Ovulation Corpora lutea
What are the major trends of progesterone and estrogen during proestrus?
estrogen decreases hyperbolically
progesterone increases hyperbolically
How long after breeding can the sperm fertilize the egg?
Species dependent.
Most: 4-6 days
Horses/Dogs: 7-10 days
When does the oocyte’s first mitotic division takes place and what is formed?
After sperm are in place but before fertilization. Creates the female pronucleus and the two polar bodies.
What produces progesterone?
corpora lutea
Where is the sperm deposited.
Species dependent.
Vagina, cervex, or uterine body
Where does fertilization of the egg occur?
In the oviduct
aka the uterine tube
What facilitates the movement of sperm to the oviduct?
Increase in mucus production of the uterus during ovulation.
What are the three key reactions of fertilization?
Capacitation, Acrosome, and Cortical reactions.
Capacitation
Sperm
Shedding of the glycoprotein coat while in the uterine tube. Exposes reactors on the head of the sperm.
Acrosome
Sperm
Proteolytic enzymes are released from the acrosomal vesicle which starts digesting the outer portion of the zone pellucida so that the sperm can enter and start the cell division process.
Cortical
Oocyte
Prevents polyspermy. After one sperm breaks in there is a large increase in intercellular calcium. This changes cell surface ligands and creates a zone-block against other sperm.
When do the male and female pronuclei form?
Female - first meiotic division just before fertilization.
Male - Directly after fertilization.
When does the fertilized oocyte become a zygote?
Once female and male pronuclei form they fuse and mitotically divide. After this division the body is considered a zygote.
What is the role of the polar bodies?
Created during first meiotic division. Help with the first mitotic division.
What is the general rule of developmental potential?
As differentiation of the cells increase, the developmental potential of those cells decreases.
VERY GENERAL (5) important functions of fertilization
- Restore the diploid karyotype.
- Determination of chromosomal sex
- initiation of cleavage
- activation of the embryonic genome
- activation of the epigenetic genome
The preformation theory
Every sperm contains a very tiny model of the animal that it will become.
The epigenesis theory
Based on actual fetal observations starting with Aristotle.
A landscape with factors pulling it different ways to create hills and valleys. Each cell is a ball that rolls down these hills to a different but mostly determined fate.
CRL
Crown-Rump Length
Used to judge the age of a domestic embryo, designed using years of empirical evidence.
Embryonic charts
Predict the stage of fetal development using age or CRL.
Hox genes
AKA Homeobox genes
Regulatory genes that help pattern the embryo with limb patterns, resp, GI, and nervous systems.
Where the genes are locate helps with this patterning.
First found in Drosophila.
ARTs
Assisted Reproductive Technologies
- artificial insemination
- oocyte transfer
- nuclear (somatic) cell transfer - CLONING
Cloning process
AKA somatic or nuclear cell transfer
Enucleate an existing oocyte. Take adult somatic cell (mammary epithelial is most common) and fuse it with the oocyte to create a reconstructed oocyte.
Why does cloning only succeed 5-10% of the time?
Creation of the reconstructed oocyte skips all of the fertilization control steps. Cannot tell if it is viable until it fails.
What are some possible future applications of cloning?
Pet cloning
Endangered species cloning
Research animal cloning
Organogenesis
Development of organs, limbs, and organic body material
Teratogenesis
The development of congenital defects within an embryo.
Gametes
Haploid genetic material carriers - the sperm and the egg.
Zygote
The embryo in a 2-cell state. Diploid with both sets of genetic material after one mitotic division.
Morula
“Mulberry” - a group of large divided cells. Relatively random. Last totipotent stage.
Blastocyst
Cells have grown much smaller and a fluid filled cavity has grown in the center. Pleuripotent cells.
Folded tri-laminar embryo
3 layered embryo proper, after gastrulation. Multipoint cells.
Fetus
After approximately 35 days of growth. Unipotent cells.
Totipotent
Cells can be ANYTHING. This only is for the first few cell divisions.
Pluripotent
All the cell types that make up the embryo and the embryonic tissues (stem cells)
Multipotent
Mesoderm, Ectoderm, or Endoderm
Unipotent
Can become only one cell type
Types of cells in the blastocyst
Zona pellucida cells
Inner cell mass
trophoblasts
Inner cell mass of the blastocyst
Cells that will form the embryo proper and the embryonic tissues.
Trophoblasts
Will communicate with maternal endometrium and help form embryonic tissues
What tells the cells what to become, where to go, and how to develop?
Differentiation: what
Patterning: where
morphogenesis: how
Zona Pellucida
Layer of compact cells. Common from the oocyte until the blastocyst
Function of the fluid filled cavity of the blastocyst
Will “hatch” out of the blastocyst to interact with the endometrium and allow trophoblasts to interact as well.
When does the blastocyst “hatch?”
Species dependent - 3 to 8 days after fertilization occurs.
CT
Computed tomography
A broad array of angles of X-rays - the same density releases for x-rays apply here.
Clinical cross-sectional imaging
CT scans
Ultrasound
MRI
MRI
Magnetic Resonance Imaging
No x-rays used
Density rules of x-rays do not apply
Why is a muscle never completely relaxed or completely flexed?
Muscles never work in isolation! Agonists and Antagonists - their work always depends on what is around them.
How do feline claws retract and extend?
Two elastic ligaments attaches P3 and P2 - the shorter of which is from the distal middle phalynx to the ungual crest and the longer of which is from the proximal interpharyngeal joint to the ungual crest. When the digital flexors work, they do not move the distal phalanges because these elastic ligaments are so strong. Protrusion requires simultaneous action of the deep digital flexor and the digital extensors.
Syncytiotrophoblast
Cells unique to primates and some carnivores. Trophoblasts that are invasive to the maternal epithelium.
Epiblast
Sheet of the ICM that will turn into the embryo proper
Hypoblast
Sheet of the ICM that will be extra embryonic endoderm, including the yolk sac.
Bilaminar embryo
Inner cell mass of the blastocyst once it has formed the epiblast and the hypoblast.
Chorion
Forms the surfaces of the extra-embryonic tissues for the most part. Wraps entirely around the outside of the tissues. From the trophoblastic and epiblastic cells.
Extraembryonic ceolom
From the blastocyst fluid and cells. Most ventral to the fetus under the yolk sac.
Yolk Sac
From hypoblastic and trophoblastic cells. Most often used for fetal/maternal diffusion of metabolites. Just ventral to the embryo and will be included in many of the tube linings.
Allantois
Cavity and membrane from the hindgut of the embryo. Will eventually fuse with the chorion. Large cavities cranial and caudal to the embryo. Allantoic cavity helps maintain pressure on the fetus and uterus so that the fetus stays against the uterine wall, especially in species that lack syncytiotrophoblasts.
Amnion
Dorsal to the embryo. Formed by the closing of the chorion over the embryo. Amniotic fluid helps to protect and buffer the embryo, especially in small animal.
Chorio-allantois
Fluid filled and MASSIVE in large animals as a buffer to the embryo. This will contact the endometrium and turn into the placenta.
Are the extra-embryonic membranes of litters common between babies or separate?
Separate, each from their own oocyte. Embryonic membranes have the genetic material of the embryo.
Zonary Placenta
Chorionic villi aggregate into a large band around the placenta. Carnivores.
Cotyledonary Placenta
Chorionic villi aggregate into small round points in various areas of the placenta. Ruminants.
Diffuse Placenta
Chorionic villi spread evenly around the placenta. Pigs and horses.
Non-deciduate Placenta
No invasive syncytiotrophoblasts.
Need specialized systems to facilitate metabolic diffusion across membranes.
Porcine and equine - two distinct membranes separating blood supply
Ruminants - one highly specialized membrane separating blood supply.
Deciduate Placenta
Invasive - some endometrial layers must come out with the fetal membranes.
Carnivores - vessel next to vessel.
Primate and rodent - maternal blood mixes with trophoblastic cells. Simplest diffusion type.
Chorionic villi
A blood vessel rich region in the placenta. In most species, a mix of fetal and maternal vessels.
What will the fate of the yolk be?
Incorporated into tube structures
Yolk stalk becomes the first blood vessels in the chorionic villi.
How long after fertilization are the embryonic membranes created?
About 1-2 weeks depending on the species.
What events is the main determinant in a viable embryo?
Gastrulation!
On which side of the embryo does the primitive node form? Which way does the primative streak travel?
Caudal end and travels cranially, creating an axis of symmetry.
What happens to the epiblastic cells as the primitive streak passes?
Formation of a trilaminar embryo.
Epiblastic cells along the streak move inwards to create mesoderm. Endoderm is hypoblast (for the moment) and remaining epiblastic cells are ectoderm.
Where is the notochord? Where is the neural tube? Where are the neural crest cells?
All are on the ventral side of the embryo
Notochord is most ventral
Neural tube is dorsal to the notochord.
Neural crest cells are dorso-medial to the neural tube.
What phylum is monophyletic on the basis of having a notochord?
Chordata
What are neural crest cells?
Pluripotent cells from the dorsal edge of the neural groove.
What are some of the possible fates of neural crest cells?
Melanocytes Spinal Ganglion Adrenal Medulla Autonomic neuron Parts of the teeth Parts of the heart Sympathetic trunk ganglion Abdominal autonomic plexus ganglion dorsal and ventral roots of spinal cord adrenal glands viscera spinal nerve dorsal, lateral, and vetral furniculi
Neuropores
Open sections (caudal and rostral) as the neural groove closes. Incomplete closure is cause of a ton of birth defects.
Spina bifida
Caudal neuropore never closes
Especially common in manx cats with no tails
In humans, folate supplementation may help
Primary brain vesicles
3 rostral expansions of the neural tube: proencephalon, mesencephalon, and rhomboencephalon. Together they look like a Kong and form the primitive brains of lampreys and others like.
Secondary brain vesicles
Forms after primary. Definitive brain structural elements of advanced animals. Will normally fill with cerebral spinal fluid and become very small but remain present in the adult brain .
Hydrocephalus
If the flow of cerebral spinal fluid out of the brain vesicles is blocked or hindered for some reason, spaces will grow enormous.
Genetic factors, intrauterine or perinatal infections or bleeding in the brain can all cause.
Neural canal
Normal adult formation out of the ventricular system (residual fluid filled vesicle spaces)
Ventricular zone
Of the spinal cord, on edges of the central canal. Mitotically active cells that give rise to new neuroblasts.
Intermediate zone
Of the spinal cord, also called the mantle. Gray matter. Between white matter and the ventricular zone.
Marginal zone
Outer portion of the spinal cord. White matter.
Basal plate
Migration of the neuroblasts of the ventricular zone. Will become the ventral horn sensory and motor neurons.
Alar plate
Migration of the neuroblasts of the ventricular zone. Will become the dorsal horn sensory and motor neurons.
Paraxial mesoderm
Mesoderm immediately lateral to the neural tube. Becomes the vertebrae.
Intermediate mesoderm
Becomes the reproductive tract.
Lateral mesoderm
Limbs and supportive CT of tubular organs.
Dorsal = somatic (body/skin)
Ventral = splanchnic (organs)
Teratology
Study of congenital defects (aka developmental defects)
Why do mutations occur?
Negative interaction between the genetic makeup of the embryo and the environment (internal or external).
Polydactyly
Extra fingers
Polymelia
Extra limbs
Atresia ani
No external anus
Very common in swine
Teratogens
extrinsic teratogenic agents or factors with the ability to cause a defect
How many animals have developmental defects?
Reported - 1% to 6%
May be higher - necropsies are not done on every stillborn animal.
Syndrome
A defect that affects multiple systems in the body.
Schistosomus reflexus
Seen in ruminants - the body looks flipped inside out. Spinal inversion, abdominal visceral herniation, ankylosis (the fusion of the joints), limb malposition, pulmonic and diaphragmatic hypoplasia.
Critical period
The time during which teratogens have the greatest effect on the embryo, usually between 3 to 5 weeks after FERTILIZATION (not breeding). This is after the totipotent/pleuripotent stage of the embryo where it can either regenerate or just die - the cells are now committed to organs. But, it is before the organ systems are reasonably stable.
Gestastional suseptibility
Dosage or duration of exposure to the teratogen.
Major causes of intrinsic teratogenesis
Chromosomal abnormalities (translocations, inversions or deletions). Worst insult. Mutations - in nt sequences.
Major classes of teratogenic agents (and an example of each)
- Infectious agents - especially viruses
(Feline panleukopenia and hydrocephalus) - Plant toxins - especially alkaloids
(Veratrum californium - cyclopia) - Drugs
(Streptomycin - ototoxicity and deafness) - Other
(Ionizing radiation, man-made toxins, metabolic disturbances - vitamins - or physical factors - hyperthermia, too much fluid, etc.)
Cyclopia
Also called holoprosencephaly. Complete or partial fusion of the orbits from incomplete closure of the rostral neuropore.
Common in sheep that are exposed to Veratrum californicum (false hellebore or skunk cabbage which contains cyclopamine/jervine alkaloids) during the critical period
Causes inhibition of the SHH signalling pathway
Can theoretically be born alive, but SHH also affects the lung and the heart - is this a defect or a syndrome?
Albinism
Intrinsic. Defect in tyrosinase affects melatonin sythesis.
Myotonia Congenita
Intrinsic. Chlorine channel defect in many species but most famous for “fainting goats.”
Malignant Hyperthermia
Intrinsic. Arg-Cys mutation affects ryanodine receptor in pigs and humans.
Vitamin A deficiency
Extrinsic. Responsible for ocular defects in cattle.
Copper deficiency.
Extrinsic. Responsible for the destruction of white matter of the cerebrum in lambs.
Laceration
Deep cut or tear in the skin or the flesh
Hemorrhage
Escape of blood from a vessel
Denervation
Loss of nerve supply due to disease, toxin, physical injury, etc.
Paralysis
Loss in ability to move and often to feel.
Contracture
Shortening/hardening of a muscle/tendon
Agonists
Two things that work in the same way or together
Antagonists
Two things that work in the opposite ways or against each other.
How should you orient a needle while giving an IM injection in the thigh of a small dog?
Caudally.
The sciatic nerve runs parallel to the groove created by the semitendonosis and the biceps femoris. If you aim cranially it is possible to hit this by going through the semitendonosis. Caudally directs the needle and liquid away from the nerve
Why are there so many extensors of the hip?
For propulsion! and they are especially large in speedy dogs.
Medial/Lateral rotation of the limb is defined by?
The cranial surface of the limb
What important structure of the dog hip does the cat does not have?
The sacrotuberous ligament
Which of the menisci of the stifle is more easily damaged?
Medial meniscus, as it is strongly attached to the medial collateral ligament. If there is a knee injury this meniscus has less room to move and so might get torn.
What elements stabalize the hip joint?
Ball and socket joint
Fibrous joint capsule
Large bulk of muscle around the hip joint
Ligament of the femoral head and transverse ligament
How does a cruciate tear usually occur in a dog?
Usually rotation while extending the limb. Usually damage occurs only to the cranial cruciate or the cranial and caudal cruciate but NOT just to the caudal cruciate.
How are the cruciate joints named?
For where they attach to the tibia
Drawer test
Measures the cranial movement of the tibia relative to the femur. Positive = damaged cranial cruciate ligament.
Falciform ligament
Just below the linea alba in the abdominal cavity.
Ligaments with roles in IVDD
Intervertebral discs (nucleus pulposus or annulus fibrosus), ventral/dorsal longitudinal ligaments, and intercapital ligaments.
