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Flashcards in Histopathology Deck (28):

How do you differentiate between adult thymus and infant thymus

From the abundance of adipose tissue


What are the densely staining and lightly staining regions in the thymus

Densely staining are the cortex whereas the lightly staining is the medulla. Cortex is densely staining because of the high number of lymphocytes and their high nucleus to cytoplasm ratio


Starry sky appearence of the cortex in the thymus due to the presence of macrophages



Most cell death occurs in the cortex of the thymus, macrophages carry out this function


What is the distinguishing feature of Medulla in the thymus? What is the name of this structure and what is its role

Hassles corpuscles

Important in Regulatory T cell development


What is this structure

Epithelia reticular cells, important in thymocytes education


What is the stroma of the thymus consist of

Epithelial cells


What is the stroma of the spleen consist of

Reticular cells


What is the stroma of the lymph nodes consist of

Reticular cells


What is this structure?

What is the distinguishing feature of this structure?

Macrophage, the distinguishing feature is the debris found around the cell.


What kind of cells form the Hassel's corpuscle and what is a marker to check for that?

Epithelial cells, keratin since hassale's corpuscles are keratinized


How do you differentiate between thymus and lymph node

Thymus doesnt have any germinal centers


What is the difference between normal and reactive lymph node? 

Explain the details of the structures that are found in the reactive lymph node

Germinal centers are obvious in a reactive lymph node, the B cells in the center of the germinal centers are differentiating and pumping out antibodies whereas the germinal center itself is lined by light staining immature B cells




What is the area surrounding the germinal centers in the lymph node

It is called the paracortex, it is the place where dendritic cells present antigens to the T cells


Know the structures of follicles and their types on lymph nodes and what is their function

Antigens presented to B cells at this site by follicular dendritic cells, follicles encircle the germinal centers in reactive lymph nodes


What cells are found at different sites of the lymph node

1. Paracortex: T cells

2. Cortex: B cells

3. Medulla: Plasma cells


Tonsils are examples of?

Mucosa Associated Lymphoid Tissue (MALT)


What are the 3 pais of tonsils

Pharyngeal, Palantine and Lingual tonsils


How to differentiate between tonsils and other structures of the immune system

Tonsils have characteristic crypts


How can we differentiate between pharyngeal tonsil and palantine tonsil

Palantine has stratified squamous epithelium whereas the pharyngeal has ciliated pseudostratified columnar epithelium


What are these and what are their funciton

Cuboidal epithelium of HEVs in tonsils, delivery of lymph to tonsils



These are transient lymphoid associated structures found in Gut (GALT), Skin (SALT), etc where they form germinal centers and stay until the infection is fought off. 


Peyer's patch

Permanent structure found underneath the lumen of the ilium where the dendritic cells present antigens and B cells and T cells proliferate to fight off the antigen


How do you differentiate spleen from other tissues

By the presence of red pulp and white pulp


What is this region, what is present here and what is its physiological function

White pulp, periarteolar lymphoid sheath surrounds this artey in the white pulp, this sheath is lined by T cells.

This is where the T cells are seeded when they leave the spleen after they are educated


Describe the structure of the follicles found in the spleen

Starting from outermost region in the spleen

1. Contain an outermarginal zone where there are T cell-Independent B cell, they identify the antigen themselves and develop an immune response towards it

2. Mantle zone which consist of T cell-Dependent B cells

3. Germinal center which contain mantle zone derived B cells which are making antibodies


What kind of circulation is in the spleen and what is its function

Open circulation, this allows macrophages to destroy the old red blood cells and scan them for antigens