Growth and Development Exam 2

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