Connective Tissue!!!!!

Good job getting through epithelium and glands! Connective tissue is definitely a lot less material than the last couple of weeks have been. For this section, I would really suggest approaching the histological naming portion thinking about the idea that "form follows function." On the quiz for this week, don't worry about writing out the full histo. name (e.g. dense collagenous connective tissue regularly arranged), the abbreviation is totally fine (e.g. DCCTRA). MAKE SURE to know though what each stands for. This will help you big time in remembering what kind of function it has. Always make sure you know all of the bolded terms in each chapter.

Key things to remember:
-DCCTRA is by far the most common type of connective tissue in the organs that we are studying this week, if you can't remember what kind of connective tissue is present in a specific organ, you're best bet is to go with DCCTRA.
-Make sure you can identify the different fibers in areolar tissue (collagen, elastic) and also be able to ID fibroblasts and know what they secrete. Your manual gives a good explanation of this if you have any q's...
-Hyaline cartilage and elastic cartilage BOTH have chondrocytes, chondroblasts, and a perichondrium (layer on the very outside of the cartilage). The ONLY way to tell them apart is that elastic cartilage has elastic fibers (why it's DECTRA) which are only visible if the cartilage is stained with Orcein-Resorcein/Verheoff's stain. The elastic fibers are very dark because of the stain. Don't get confused though because hyaline cartilage can be stained darker (e.g. purple) too, but it will be a uniform darkness. See below for pics of how elastic fibers cause a non-uniform darkness from the stain.

Examples above are all Elastic cartilage. Notice the contrasting for the elastic fibers and the extracellular matrix.

Hyaline cartilage. Notice how the extracellular matrix (space outside of chondrocytes) is much smoother?? No elastic fibers...

-Fibrocartilage has NO perichondrium, and most often does not have a noticeable chondroblast layer (though it can...). It will have visible chondrocytes if zoomed out, and a meshwork of irreg. fibers if zoomed in. Look in your lab manual for a good example of both. 

Fibrocartilage. Notice the lack of a perichondrium/chondroblasts.

-Know where to find lamina propria! In the intestinal tract (just deep to the epithelium layer before you get to the submucosa) and in the oviduct (also just deep to the epithelium layer). 

-The hepatic/glisson's capsule surrounding the liver is DCCTRA as are almost all capsules. Students are often confused when they see a zoomed out picture of the liver. It has many lobules and they are very noticeable when zoomed out. Don't get confused if you see that!

See the lobules?? 

-Tendons have a general waviness to them which is especially noticeable when zoomed out further than the picture in the lab manual and they help to connect muscle to bone. They can be other colors than pink as is shown in the manual. They have NO horizontal striations which makes them look different than muscle. 

Both photos above are of tendon. Compare them with the one below of skeletal muscle. See the horizontal striations in the one below? That's one key way to tell them apart.

-Ligaments - Don't stress too much about them. Know that they connect bone to bone and that they have elastic fibers (thus DECTRA instead of DCCTRA). What stain would you use to make the elastic fibers visible?

-Know all the terms in the section about bones....

-Make sure you can find endochondral bone formation before your quiz! Each box has an endochondral bone slide, but it is often hard at first to find where in the slide the endo. bone formation is occurring. These are easy points as long as you can find it on your slide!
Remember: Real
                   People
                   Help
                   Cancerous
                   Rats
Some hints for each zone: zone of reserve (think reserved people stay by themselves) has mostly single/double cells that are fairly flat. Zone of proliferation (think, they are prolific

and having lots of kids...) shows mostly flat cells, but they are in columns with several others. Zone of hypertrophy, the number of cells in the columns don't change, but they are much bigger (more swollen looking). This layer is probably one of the best landmarks because it is usually the most visible. Zone of calcification is immediately after the zone of hypertrophy where there are no more visible cell membranes because the cells are becoming calcified. If asked to identify it, point immediately after the zone of hypertrophy or else you risk pointing to the zone of resorption. If asked to point to the zone of resorption, make sure you are not right next to the zone of hypertrophy. 

-For the developing tooth, pick a landmark! I like to use dentin as mine. It is often the most recognizable and is always thick and colorful (usually bright pink). Make sure to know that the ameloblasts secrete enamel inward toward the tooth and that odontoblasts secrete the dentin outward. Know what the ameloblasts and odontoblasts are histologically, and make sure that if you are asked to point them out, that you are pointing to the right layer! They are fairly obvious because they are and look like simple columnar!

 

All pics of developing teeth. Notice how the dentin layer is the most obvious landmark in each?? (Top left=the lighter pink, smooth layer; top right=bright pink thick layer; bottom=bright pink thick layer) I would suggest identifying the dentin layer and then working out/in from there.

-For the spleen, look for a thick capsule with lymphatic nodules as your landmarks. Please do not think that white pulp is what looks white and the red pulp is what's red!!! The white pulp is what is inside the lymph nodules (see the pics below) and the red pulp is everything surrounding the lymph nodules. 

See the thick capsule? The circular parts are the lymph nodules.

-The internal elastic laminae is the squiggly dark line (stained with orcein-resorcein) you see near the lumen of arteries (most obvious on medium sized arteries) and the external elastic laminae is the collection of dark squiggly lines a bit deeper once you get past the smooth muscle. The tunica adventitia is immediately after the external elastic laminae. When the artery is in diastole (relaxed), the squiggly lines are also relaxed and they remain squiggly --> DECTIRA (squiggly lines are irregularly arranged...). When the artery is in systole (blood is higher pressure), the elastic laminae are stretched and are no longer squiggly --> DECTRA (regularly arranged). YOU WILL NEVER see a slide of an internal or external elastic lamina in systole (the animals are no longer living, thus their hearts are no longer pumping... :) ). 

-Finally, make sure you can find some examples of adipose (unilocular adipocytes) on your own slides. Some good places to check are on your parotid slide or around vasculature.

Good luck this week! Let us know if you have any questions.

Connective Tissue Key Terms

Key: Know the anatomical and histological names (including modifications) for the following bolded structures; assume that you will be required to find the structures indicated by * on your own slides.

***This list is not guaranteed to be exhaustive, and only includes terms from this unit. While we will not focus on quiz information from previous weeks, knowledge of previous material may be useful***

Focus on connective tissue histology, but keep in mind all of the following terms.

Basic Connective Tissues

Aerolar Connective Tissue

·       Aeolar connective tissue*

·       Fibroblasts*

·       Collagen fibers*

·       Elastic fibers*

Hyaline Cartilage

·       Hyaline cartilage*

·       Chondroblast layer*

·       Chondrocytes*

·       Nest cells*

·       Perichondrium*

Elastic Cartilage

·       Elastic cartilage*

·       Chondrocytes*

·       Chondroblast layer*

·       Perichondrium*

Fibrocartilage

·       Fibrocartilage*

·       Nest cells*

·       Chondrocytes*

Digestive System

Intestinal Tract

·       Lamina propria*

·       Muscularis mucosa

·       Submucosa*

Liver

·       Glisson’s capsule*

Musculoskeletal System

Tendon

·       Tendon*

·       Collagen fibers*

·       Fibroblast nuclei*

Ligament

·       Ligament

·       Elastic fibers

·       Fibroblast nuclei

Bone

·       Haversion canal*

·       Osteocytes in lacunae*

·       Canaliculi*

·       Concentric lamellae*

·       Interstitial lamellae*

Endochondral Bone Formation

·       Zone of reserve*

·       Zone of proliferation*

·       Zone of hypertrophy*

·       Zone of calcification*

·       Zone of resorption*

·       Perichondrium*

·       Periostium*

Developing Tooth

·       Dental pulp*

·       Odontoblast layer*

·       Predentin*

·       Dentin*

·       Enamel*

·       Ameloblast layer*

Respiratory System

Trachea

·       Chondroblast layer*

·       Perichondrium*

·       Tracheal epithelium

Dermis

·       Dermis*

·       Epidermal epithelium

Lymphatic Tissue

Spleen

·       Splenic capsule*

·       White pulp*

·       Red pulp*

Lymph Node

·       Reticular fibers

·       Dense lymphatic tissue

Cardiovascular

Blood Vessels

·       Internal elastic lamina (systole and diastole)*

·       External elastic lamina (systole and diastole)*

·       Tunica adventitia*

Miscellaneous

Adipose Tissue

·       White adipose cells*

Oviduct

·       Oviduct epithelium

.        Lamina propria*

Exocrine

Congratulations on getting through the first three lab lectures and quizzes! I know they can be daunting because of the sheer volume of material. Really work at mastering each week's material, because it will help you not only for that week's quiz, but also for each one that follows. The load lightens up quite a bit here soon, I promise :)

Key points from this week:

For the exocrine portion of the lecture, make SURE you know each gland anatomically and histologically, as well as what organ it pertains to (e.g. Brunner's gland (anatomical name) is CMBT and is part of the duodenum (small intestine)). Also, be sure to study what each gland secretes. All of these are fair game for the quiz. There is quite a bit of memorization involved with exocrine glands because there isn't a real clear connection between the gland classification (e.g. SMBT) and its function (besides that more active glands are usually alveolar as opposed to tubular). If you are creative and want to make up your own mnemonics, that's fantastic! Feel free to share them and I'll post them here, along with these:

CMTA ('Cat milk tastes awful' or 'Come meet the acid'): subesophageal, submandibular, and proliferating mammary
UNICELLULAR = paneth and goblet cells
CMBT ('combat') in the Brunner's - think an acid/base 'combat' ;)
SMBT ('smell my big tummy' or 'sweet mamma's birthing time'): smell = olfactory (Bowman's) my big = pregnant (uterine) tummy = (gastric) 
CMA ('came along') in the PPVLL (pancreas, parotid, von ebner's, liver, and lactating mammary)
SMTA ('some men talk a lot') in the sub-tracheal
CMT ('cow milk trapping') = resting mammary 
CMBTA ('?') in the prostate
SMCT ('smell my clean trickle') in the sweat gland
SMBA ('smell my bad air) remember, the sebaceous gland secretes sebum, which can attract foul-smelling bacteria

Blue=Histological
Red=Anatomical
Broken up so that each line only contains one histological name with the corresponding anatomical names.

***Only use this if you memorize the whole thing, otherwise I think it will confuse you more than it will help :)***

Other things to remember from glands:
-Goblet cells decrease down the respiratory tract and increase down the GI tract --> you would be most likely to find them in the large intestine and trachea and least likely in the esophagus and terminal alveoli. If you're asked to find one on a U-Find, go straight for the large intestine. There are TONS there.
-Sub-esophageal and sub-tracheal glands can look pretty similar, but are obviously distinguished by the epithelium (strat. squamous for sub-esoph. and ciliated pseudo. colum. for sub-trach.) and the presence/lack of cartilage c-rings (sub-trach has the c-rings).

Can you see the difference in the epithelium in the above pics?

- Also, just to clarify: Paneth cells are found in the crypts mostly of the small intestines, but may be found sporadically throughout the cecum and appendix. Paneth cells are acidophilic, meaning that they are usually stained brighter colors (usually red). Also, just something interesting, Paneth cells are located adjacent to stem cells at the base of the intestinal crypts which are responsible for the long-term maintenance of the epithelium. Paneth cells play a role in protecting these stem cells by secreting antimicrobial enzymes.

Check out those paneth cells!! (The red cells)

-Brunner's gland is only in the duodenum. If asked to identify the location of the gland, be as specific as possible. Don't just say 'small intestine', put 'duodenum'.
-The submandibular/submaxillary glands can sometimes be tricky for people. Look for serous AND mucous acini. The biggest landmark for these are the demilumes (look like a half-moon because of one side of serous and one side of mucous acini)

See the moon shape?

-Parotid look similar to submandib., but only have the darker serous acini. You will also often see adipose (fat) tissue in the parotid gland. Don't confuse it for something else . . . just remember, you won't be able to see the nuclei of the adipocytes, but you CAN see nuclei in mucous acini.

Parotid Gland. White lobules are the adipose.

-A big landmark for the liver are the binucleated hepatocytes and also the liver is split into lobes without any other major structures (besides the hepatic triad)
-Pancreas can look a lot like the parotid gland, BUT it will have islets of langerhans (lighter colored islands --> help w/endocrine function).

Parotid - see the ducts?

Pancreas w/islet of Langerhans

- Notice how both pictures have areas that are lighter than the surounding acini; however, in the top picture, the lighter cells are obviously cuboidal with a central lumen - those are the ducts of the parotid exocrine gland. The bottom picture on the other hand, has an islet of Langerhans with very non-cuboidal cells arranged in kind of a jumbled, messy way. You can't see any ducts/lumens because this part of the pancreas is endocrine.

-The biggest landmark for the Bowman's is the epithelium (ciliated pseudo. colum.). It usually is very thick and you usually won't see any nuclei at the apical 2/3's.
-For the Uterine gland, remember the analogy of the wild leopard spots :) The uterine gland is truly unique and should be easy points on the quiz if we show you a picture.

Resting mammary - what is this histologically???

Lactating Mammary

-Remember that the mammary glands secrete COLOSTRUM, not milk. If there are lots of follicles and they all look full with colostrum, it is lactating. If there aren't many at all, and they aren't really filled with colostrum, it is resting. In between those two is proliferating.

-Both the sweat and sebaceous glands are found in the dermis (deep to the epidermis). The sweat glands have distinguishable ducts (look like sliced tree trunks) whereas the sebaceous ducts aren't as distinguishable (looks more like a cluster of grapes). The sebaceous glands are oftentimes right by a hair follicle (where they secrete the sebum into).

Sweat or sebaceous??? (starts w/ S and ends in weat...)

Exocrine Review Sheet

Key: Know the anatomical and histological names (including modifications) for the following bolded structures; assume that you will be required to find the structures indicated by * on your own slides.

***This list is not guaranteed to be exhaustive, and only includes terms from this unit. While we will not focus on quiz information from previous weeks, knowledge of previous material may be useful***

Focus on exocrine gland histology, but keep in mind all of the following terms.  Know the specific secretions from each exocrine gland as outlined in your lab manual.

G.I. Exocrine Glands

Esophagus

·       Subesophageal gland*

·       Esophageal epithelium

Unicellular Exocrine

·       Goblet cells*

·       Paneth cells*

Small Intestine

·       Brunner’s gland*

·       Mucosa

·       Submucosa

·       Muscularis Externa

·       Intestinal epithelium

Stomach

·       Gastric gland*

·       Parietal cells*

·       Chief cells*

Digestive Enzyme Secreting Glands

Submandibular/Submaxillary

·       Submandibular/submaxillary salivary glands*

·       Serous acini*

·       Mucous acini*

·       Demilunes*

Parotid

·       Parotid salivary gland*

·       Serous acini*

.        Adipocytes

Tongue

·       Von Ebner’s gland*

·       Circumvallate papillae

·       Taste bud

·       Skeletal muscle irregularly arranged

Liver

·       Liver (as an exocrine gland)*

·       Hepatic lobules*

·       Hepatocytes*

·       Hepatic artery*

·       Hepatic portal vein*

·       Hepatic bile duct*

·       Bile canaliculi

·       Hepatic sinusoids*

Pancreas

·       Pancreatic acini*

·       Islets of Langerhans*

Respiratory Exocrine Glands

Trachea

·       Subtracheal gland*

·       Hyaline cartilage (C-Rings)

·       Trachea epithelium

Olfactory

·       Bowman’s gland*

·       Olfactory epithelium

Reproductive Exocrine Glands

Uterus

·       Uterine gland*

·       Endometrium

·       Myometrium

Mammary Gland (Resting)

·       Mammary gland

Mammary Gland (Proliferating)

·       Mammary gland

Mammary Gland (Lactating)

·       Mammary gland

·       Connective tissue

Prostate

·       Prostate gland*

·       Glandular acini

·       Concretions

Seminal Vesicle

·       Seminal vesicle epithelium

·       Muscularis externa

·       Connective tissue

Integument System

Sweat

·       Sweat gland*

·       Dermis

·       Hair follicle

Sebaceous

·       Sebaceous gland*