Histology Review Part 2

• transitional epithelium (dome shaped and/or bi-nucleate cells)

trachea

• ciliated pseudostratified columnar epithelium with goblet cells

  • also refered to as respiratory tract epithelium but do not write that name on the exam

epididymis

• pseudostratified columnar epithelium with stereocilia

• remember that stereocilia are just long microvilli (actin microfilaments) so they are not real cilia

Note: here is a hint about the pseudostratified epithelia, the above two examples are the only instances where you will see them therefore, if it does not have either cilia or stereocilia, IT IS NOT PSEUDOSTRATIFIED even if it looks like it might be! You will also never see cilia or stereocilia on any other epithelium therefore, to determine if it is pseudostratified, first look for either one of those two surface specializations. This is a constant rule so use it for your practical!

tendon

• dense regular connective tissue (do not call this tendon on the exam)

• looks very much like smooth muscle and longitudinal section of nerve *therefore compare the three side by side to see the subtle differences

hyaline cartilage

• chondrocyte cell in a lacuna (you have to write lacuna otherwise it is wrong)

• isogenous group (remember this is interstitial growth)

• territorial and inter-territorial matrix

  • territorial matrix is darker because of the preponderance of GAG’s

  • remember this is collagen type 2 (type 2-blue)

• perichondrium

• remember this part is collagen type 1 (pink)

developing membranous bone (fetal finger)

• perichondrium vs. periosteum

  • just what the name says, if it is the part over the cartilage it is perichondrium if it is over bone it is periosteum. These two structures are continuous with each other.

• know the five zones (resting, proliferating, hypertrophy, calcification, and ossification) remember that the process here is endochondral ossification

• **Sharpey’s fibers simply connects the periosteum to the bone collar

• bone collar (remember this is direct bone formation)

• cell types: osetoclast (large multinucleated), osteocyte and osteoblast

Note: One question that everyone seems to ask me is the difference between appositional, interstitial, direct and endochondrial bone formation. I know it has nothing to do with your slides but since it is confusing I will mention it.

First, you are describing two separate things that is growth vs. bone formation. They do not mean the same thing. When talking about growth you use the terms appositional and intramembranous to describe it.

Appositional (bone and cartilage) is when cells (...blasts) move from the outside in and become (...cytes). Interstitial (cartilage only) is when the chondrocytes divide within the middle of the cartilage and form isogeneous groups that eventually spread out. Bone formation refers more to the embryology of bone. Direct or intramembranous bone formation is what happens in the bone collar. Bone is directly made from embryonic mesoderm. Endochondrial bone formation is just what the name says, cartilage is made first then it turns to bone (indirect) and this is what is happening in the epiphyseal plate.

compact bone

• Haversian system or osteon

• osteocyte in a lacuna (must write lacuna)

• canaliculi (house cytoplasmic extensions of the osteocyte cell)

• interstitial lamella

  • broken down osteon that looks like nothing significant in between osteons

Category: Anatomy Notes