A 60-year-old woman with poorly controlled hypertension undergoes surgical repair of a popliteal artery aneurysm. A thin strip of the arterial wall is submitted for routine H&E staining. On the glass slide, the resident is asked to name the epithelial layer that forms the luminal surface of the vessel.

Which type of epithelium lines the lumen of this artery?

A 58-year-old man undergoes transurethral resection of a non-invasive bladder tumor. A separate biopsy of grossly normal mucosa is sent to the histology lab for comparison. On the H&E slide, the resident must identify the epithelial lining of the bladder lumen.

Which type of epithelium lines the luminal surface of this biopsy?

A 30-year-old traveler develops profuse watery diarrhea after eating contaminated seafood. Stool culture grows Vibrio cholerae. Electron microscopy of the jejunum (part of the small intestine) shows interlocking strands that seal the top edges of neighboring intestinal (epithelial) cells.

Which type of cell junction is mainly responsible for forming this paracellular seal?

A duodenal biopsy from a 24-year-old woman with chronic diarrhea is examined by transmission electron microscopy. One side of each enterocyte is covered with densely packed microvilli and directly borders the intestinal lumen.

Which membrane domain is being shown?

A 25-year-old soccer player tears his anterior cruciate ligament. During reconstructive surgery, a small piece of the ruptured ligament is sent to pathology. Light microscopy shows parallel bundles of collagen fibers with scattered fibroblasts embedded in ground substance.

What is the chief function of this tissue type?

A 40 year old female has recently been diagnosed with breast cancer. Her consultant explains that in breast cancer, the Estrogen Receptor (ER) status has high prognostic ability.

Which technique is used to identify the ER in this case?

The Papanicolaou stain is a polychromatic stain used for the detection of cervical cancer (among others). It uses 3-5 dyes to stain different components of the cells. One of the dyes used is haematoxylin.

Which structure in the cell will be stained by haematoxylin?

A 58-year-old with long-standing hypertension is enrolled in a study on microvascular remodeling. Researchers obtain the following high-magnification image of a small vessel that highlights the three-dimensional surface topology of the luminal lining and the surrounding smooth muscle architecture.

Which imaging technique was used to obtain this image?

A PhD student is studying the role of the cytoskeleton in dividing myoblasts. In order to stain the actin cytoskeleton in these cells, he uses anti-F actin antibody conjugated to FITC (a fluorescent dye). He then visualizes the cells using a fluorescent microscope.

Which staining method does this represent?