bones of limbs come from
somatic mesoderm
fleshy part of mouth comes from
prechordal plate
average gestation length of: chicken, pig, sheep, cattle, horse
chicken: 21 days
pigs: 114 days
sheep: 147 day
cattle: 283 days
horse: 340 days
*all dependent on breed
how do you differentiate between an embryo and a fetus
considered a fetus when you can tell its a specific species, anything before is an embryo
fetus- identification to parturition
during maternal membrane development, where does each structure form from
trophoblast- chorion
hypoblast- yolk sac, allantois
mesoderm- chorion, amnion
ectoderm-amnion
what is the function of the amnion
protection
forms a closed sac in which the developing embryo is immersed
what is the function of the chroion
forms the placenta
becomes the outer membrane of the placenta
what is the function of the allantois
forms the umbilical chord
what is the function of the yolk sac
source of nutrition. larger in poultry, disintegrates in other species after placenta is formed and able to provide nutrients
5 bones types
long
flat
short
irregular
sesamoid
long bones
femur, tibula, humerus
flat bones
scapula, pelvis, ribs
short bones
tarsal, metatarsals
irregular bones
vertebrae, mandible
sesamoid bones
patella
(not attached to other bones)
navicular bone
a sesamoid bone in the hoof of the horse
can cause inflammation, causes 1/3 of lameness
tendon
bone to muscle
ligament
bone to bone
mesenchymal cells produce
osteochondroprogenitor cells
osteoblasts come from and produce
osteoprogentior cells
produce osteocytes and bone lining cells
chondroblasts come from and produce
chondroprogenitor cells
produce chondrocytes
osteoclasts come from
hematopoitetic origin
what are the 2 types of ossification
endochondral and intramembranous
endochondral ossification
replacement of cartilage with bone
intramembranous ossification
replacement of connective tissue in absence of cartilage
major difference b/w primary and secondary ossification
primary ossification happens in diaphysis
secondary ossification happens in epiphysis
steps of primary ossification
start with cartilage as template for bone
cartilage starts producing matrix that will calcify
once cartilage calcifies, chondrocytes die off
osteoblasts start to come in and invade cartilage
capillaries start to come in
osteoblasts produce osteocytes form
steps of secondary ossification
same as primary but in epiphysis
thin layer of articular cartilage remains for lubrication
growth plate forms
growth plate (aka epiphyseal plate)
cartialge remaining b/w epiphysis and diaphysis
what are the zones of growth plate organization
reserve zone
proliferative zone
prehypertrophic zone
hypertrophic zone
what is the order of bone growth maturity
posterior to anterior (opposite of other growth)
sacral vertebrae --> lumbar vertebrae --> thoracic vertebrae
steps of intramembranous ossification
replacement of CT by bone in absence of cartilage
mesenchymal cells differentiate directly to osteoblasts
osteoblasts produce collagen fibers and bone matrix, differentiate into osteocytes producing bone
appositional bone growth
growth involves addition of new layers on previous formed layers so that bone growth in girth
osteoclast
involved in bone reabsorbtion
eat away at bone by releasing acid and uptake of calcium salts
produces cavities for marrow
can cause problems if it occurs faster than actual bone buildup
what is bone matrix made of
-calcium and phosphate salts (hydroxyapatite and calcium carbonate)
-collagen
bone remodeling
deposition and resorption process that lead to change in size and shape of bone during growth
regulation of bone growth includes
calcitonin/parathyroid hormone, estrogen/testosteron, nutrition and vitamins
calcitonin function
decrease osteoclast activity
decrease blood calcium
parathyroid function
increase osteoclast activity
increase blood calcium
estrogen function on bone
increases ossification. closes growth plate faster
faster than testosterone
testosterone function on bone
increases ossification- closes growth plate faster
what is the bone length comparison of females vs males vs castrates
castrates>intact males>females
nutrition effect on bones
too fat too soon = structural problems
vitamin effect on bones
vitamin deficiencies = improper bone growth
dyschondroplasia
insufficient cartilage degradation, doesn't properly ossify
epiphysiolysis
separation of epiphysis
caused by necrosis of chrondrocytes at growth plate, blood vessels aren't able to form
osteoarthritis
deterioration of cartilage surrounding joints
causes joints to become chronically inflammed
what are the 5 steps in muscle development
1. delamination
2. migration
3. proliferation
4. determination
4b.--proliferation
5. differentiation
what is the pneumonic for remembering the 5 steps of muscle development
delightful migrants promote detailed (profound) differences
what is delamination
separation of myotome from dermomyotome and sclerotome
what is migration
myogenic progenitor cells travel to eventual site of muscle formation
what is proliferation
hyperplasia of myogenic progenitor cells
what is determination
genetic factors are expressed which direct myogenic progenitor cells to become myoblasts
cells are
committed
what is 4b proliferation
proliferate as now committed myoblasts
muscle regulatory factor genes (MRFs) for 4b proliferation
Myf5
MyoD
what is differentiation
myoblasts form myotubes, which form muscle fibers
stop dividing and cells begin to align with one another and fuse together creating myotube
muscle regulatory factor (MRFs) genes for differentiation
myogenin
Mrf4
what are MRFs
genes that encode proteins involved in regulating muscle cell development
expression of these genes triggers determination/commitment
what are the properties of myoblast
primitive muscle cells
spindle shaped
bipolar, central nuclei
still have capacity to divide
cannot contract (no actin/myosin contracting proteins)
myotube development is ________________
biphasic
primary and secondary myotubes
does myotube development happen prenatal or postnatal or both
only prenatal
primary myotubes
from embryonic myoblast
act as scaffolding
almost entirely controlled by genetics
secondary myotubes
from fetal myoblast
build around primary myotubes
development affected by environmental factors (such as nutrition)
difference b/w myotube and mature muscle fiber
myotube
developing myofibrils
can contract (unorganized)
multinucelated
central nuclei
mature muscle fiber
developed myofibrils
can contract
multinucleated
nuclei at periphery
does muscle fiber number increase after birth
no
muscle fiber number is affected by
muscle differences
species
nutrition (in utero)
age (loss of muscle fibers)
sex (males more than females)
genetics
if something has less muscle does it have less fat or more fat
more fat
double muscle cattle is due to a mutation in ____________
myostatin
results in ~40% more muscle fibers
belgian blue, piedmontese, charolais
postnatal muscle fiber growth involves hyperplasia or hypertrophy?
hypertrophy
postnatal muscle growth in length
longitudinal
-stretch induced hypertrophy
-increase in sarcomeres (addition at distal ends)
postnatal muscle growth in diameter
radial
-work/exercise induced hypertrophy
-increase in myofibrils (myofibril splitting)
what is the key for muscle growth (hypertrophy)?
satellite cells
satellite cell function
muscle growth by supplying additional nuclei
repair damage
muscle fiber size can be affected by
nutrition
age
sex
genetics
growth promotents
speices
protein turnover
process of protein replacement
process of protein synthesis
AA's --> protein
DNA transcribed into mRNA
movement of mRNA into sarcoplasm
translation of mRNA into protein
post-translational processing of protein (modifications)
positioning of protein
what are the 3 systems of protein degradation
lysosomal system
calpain system
ubiquitin-proteasome system
lysosomal system
uses
cathepsins
(enzyme)
20-30% of all degredation
cystatin
- inhibitor
calpain system
cuts proteins into chunks
calpain 1
&
calpain 2
- proteases
calpastatin
inhibitor
callipyge
beautiful butts- in sheep
causes by calpastatin mutation
ubiquitin-proteasome system
cuts proteins into really small peptides
ATP dependent
synthesis > degredation
hypertrophy
synthesis < degredation
atrophy
synthesized protein - degraded protein
accretion
white fibers vs red fibers
white
(type 2B)
speed
larger
less protein turnover
heavier muscled/more efficient
red
(type 1)
endurance
smaller
more protein turnover
adipose tissue is what kind if tissue
loose connective tissue
adipose tissue is primarily composed of
adipocytes
adipose tissue contains high proportion of
lipids
genetic regulation of adipogenesis is done by:
PPARgamma- signals lipid accumulation
C/EBP- adipocyte differentiation and determination
ADD1/SREBP1- adipocyte differentiation and determination
do hyperplasia and hypertrophy of adipocytes happen pre or postnatally
hyperplasia- both pre and post natal
hypertrophy- postnatal only
what are the 4 fat deopts
visceral
SQ
intermuscular
intramuscular
mesenteric fat
around intestines
caul fat
around stomach/rumen
aka lace fat
perirenal fat
around kindeys
leaf fat
specific to pork carcasses
foie gras
fatty liver"
force fed geese/ducks in order to produce a fat covered liver for fine dining
who has the most SQ fat
pork
beef is lowest
who has the most intermuscular fat, intramuscular fat, and kidney fat
beef
pork lowest
two methods of fat deposition in adipose tissue
from blood
de novo
what is the difference b/w the two methods of fat deposition in adipose tissue
from blood FA sythesis
extract FA's from triglycerides in blood
nutrients from feed
from liver FA synthesis
de novo
"from new"
FA synthesis
requires precursors and enzymes
nonruminatns- glucose
ruminants- VFA's
fatty acids are ____________ in adipocytes to form triglycerides
esterfied
lipolysis
removal/release of FA's from adipocytes
_________ break down triglycerides into fatty acids in order to cross membrane
lipases
factors affecting amount of metabolism of adipose
age
anatomical location
species
genetics
sex
hormones
nutrition
enviornment
brown fat
only in newborn livestock
brown b/c of high mitochondria composition and size
greater number of capillaries
may have same origin as muscle (express myf5)
after prenatal phase, depleted or involutes into white fat
mitochondria in brown fat produce ________ instead of ATP
heat
nonshivering thermogenesis
nonshivering thermogenesis
...
factors affecting brown adipose tissue
prematurity
species (poultry-none, piglets-minimal, bos indicus vs bos taruas- same amount but B.i don't do as well in cold temps)
environment
nutrition