after i tell you how to differentiate
the six types of connective tissue proper i have 10 practice questions so when you're
looking at connective tissue you want to think what fiber types am i seeing what
directions are those fibers going in and it can also be helpful to look at the type
of cells and the quantity of cells you're seeing so there's three possible fibers collagen
elastic and reticular collagen is the thickest elastic is medium and reticular
is the finest now i did put colors but the color is going to depend on what type
of stain was used to stain the slide collagen and elastic are visible with the most common type
of stain that they use as being pink and purple but the reticular usually you can't see it
because that requires a special type of stain so looking at the first one that's the easiest
that everyone learns very quickly that is adipose you don't have to worry about the fiber
types it's just a bunch of fat cells so each one of these bubbles is a singular fat
cell and the inside is filled with a drop of fat the biggest problem people have with adipose is that people will see simple
squamous and think that it's adipose i'm gonna make a short video about that issue
and pin it in the comments once i make it so the tissue next door in the background
you're seeing kind of out of focus thicker pink fibers and in the
foreground these black looking fibers so this is areolar connective tissue and the defining characteristic of it is that
you have these pink collagen fibers and the black to purple elastic fibers randomly arranged
in many directions and there's a lot of open space because a reeler is a loose connective tissue as
opposed to a dense connective and there's also usually lots of these little black
dots which are cells called fibroblasts over here so if you compare these black thready fibers to the
fibers that you're seeing in areolar you'll notice that they look more like a net and more like a
mesh whereas the areolar ones are very straight now those are the reticular fibers so
this is reticular connective tissue and this is the one where you
need a special stain to see it now when you're first learning usually the example they show you is a lymph node and in a lymph
node you have lots of these circular cells so those circular cells you're seeing
are also a hint that this is reticular so all these ones on the top
are loose connective tissues because they're not packed as densely
they don't have as much collagen if we go down to the bottom now
this is a dense connective tissue so if you see the fibers they're
kind of stained a light pink this is why you can't rely on color too much
because many people would not see that as being pink but you see that the fibers are all going in
one direction and these cells are kind of smushed in between the different fiber bundles
this is dense regular connective tissue so it's called regular because the fibers are
running in one direction next door we have fibers running in many directions so you have some fibers
running this way and then this was a bundle of fibers that was kind of coming straight at us and
then it got cut so we're seeing like the stumps that have been cut so because these collagen
fibers are running in many different directions this is dense irregular and over here now this type of tissue is not very
common and all the examples i have ever seen do tend to look pretty much like this you're
seeing wavy elastic in the foreground and in the background it's kind of over a bed of pink
collagen fibers this is elastic connective tissue not to be confused with elastic cartilage which
is an entirely different tissue if you want to learn about cartilage i will pin a link in the
comments i have a special video just for cartilage okay so i'm going to show
you 10 practice questions and i'm going to give you 10
seconds to think about each question before i explain what the correct answer is and
how you should have been able to know what it was okay so you should see that we have fibers
going in one direction we only see one fiber type which appears to be collagen because it is
pink and sandwiched in between we see fibroblasts and that's how you should know it's
dense regular connective tissue i'm not even giving you 10 seconds
because i know that you know when you see all these little bubbles all these
very thin little bubbles you're looking at adipose okay so you're seeing black
fibers that are making a net which lets you know you're looking
at reticular connective tissue all right so this very much
looks like hamburger meat what you're seeing is fibers going in
all different directions that have been cut that's how you know that you're looking
at dense irregular connective tissue so you have these black fibers going in
all different directions in the foreground and there's kind of a haze of pink in the
back that haze of pink is collagen fibers which are out of focus and you're seeing
many of these little black circles which are fibroblasts and all of those things should
tell you that this is areolar connective tissue okay so i cheated this is not connective tissue
this is simple squamous um and this is how people are going to confuse it with adipose because they
see lots of open space and circles and they're like oh adipose but what you need to pay attention
to is all those little black specks are nuclei um that tells you that this is multiple
cells it's not just one fat cell we have multiple nuclei multiple cells so this is
many little squamous cells making a circle also you'll notice if you compare side
by side squamous simple squamous um this isn't a lung it's not perfect little
circles they're kind of irregular circles and if you need more help like i said i'm
gonna make a video specifically just about this okay so you're seeing purple little
waves those are bundles of elastic and it's over a background of
collagen which is kind of out of focus and that tells you that this
is elastic connective tissue so this is further away than you've seen it before
but even though you can't see the individual fibers you can kind of see the wavy pattern in
the background and you've got a bunch of cells here which are smooshed so what you're seeing is
fibroblasts smushed in between collagen fibers so this is your dense regular connective tissue
people sometimes will see certain types of smooth muscle and confuse it with this i'm going to
make up a whole other video about that as well so once again black purple elastic over
pink it's elastic connective tissue and lastly are fibers going in all different
directions two different fiber types are visible little black specks which are fibroblasts
has to be areolar connective tissue Alright, i hope that was helpful
have a great day and have fun learning