Hematolymphatic system(HLS)

Anatomy Lab 2

DONE BY:Atiqa Dahalan

ATYAF GROUP (2007)أطياف بتضلها أطياف

Disclaimer

1. The content of this slides may vary from what you discuss from your lab.

2. The pictures may or may not be the same as what you see in lab because some of them are obtained from the internet.

3. The best reference will still be your notes and books.

Lymph Node• Q: Why is this a lymph node?

• A : First, it has capsule. Below the capsule we can see subcapsular sinus which appear even in low power magnification. It also has inner and outer cortex and medulla. The darker cortex at the periphery of the node has nodules, some of which show pale, mitotically active germinal centers. The dark stained area shows inactive, primary follicle/nodule while the lighter stained area means secondary follicle/nodule which is active.

• At high magnification, we can see clearly capsule and subcapsular spaces. The dark stained cells with large nucleus are lymphocytes. It is B-lymphocyte. There is also reticular cells and reticular fibers which build up the lymphatic organ.

• The white color spaces in the medulla is called sinuses. On the other hand the cellular portion is called cord.

• Here we can see macrophage in lymph node medulla. We know that this is macrophage because it is a huge cell with some substances inside the cytoplasm.

• Again, to summarize a lymph node, we have

– Capsule– Subcapsular space– Inner cortex– Outer cortex– Medulla– Sinuses

Spleen

• We may see arterioles in spleen, located in germinal center.. It is central arteriole, but sometimes it may be eccentrically located.

• We may also see blood vessels in trabecula of the spleen.

• A spleen has capsule and trabeculae, just like lymph node. However, it doesn’t consist of subcapsular space. There is also lymphatic follicle. If we take a fresh spleen, we can see white patches and red background of the spleen. The white patches, or also known as white pulp composed of lymphatic nodule while the red background is also known as red pulp.

• In the red pulp of spleen, we may see lymphocytes. In fact we can see all types of blood cells including RBCs.

• The space between red pulp and white pulp is “marginal center”

Thymus (Fetal)• Q: Why is cortex differently

stained than medulla.• A: The cortex is darkly

stained due to its cellularity. It has more lymphocytes, (T-lymphocytes) and other compositions include epithelial cells and macrophages. Note: We can’t differentiate between B-Lymphocytes and T-Lymphocytes from a histology slide.

Thymus (Adult)

• We can see adipose tissue in adult thymus, and the thymus tissue will disappear.

• The major cell type in the cortex is the T-lymphocytes, in the lighter area, we have epithelial cells and smaller cells.

• Meanwhile, in the medulla we have T-lymphocytes, epithelial cells and macrophages.

• Here we can see Hassal corpuscle in the medulla of thymus with concentric layer of keratinized cells. In the exam, we can be sure that it is a thymus if we see there is Hassal corpuscle.

How to differentiate between Thymus and Lymph Node?• There is no follicle in thymus• Subcapsular sinus is only found in lymph node…

Tonsils

• The tonsil is partially capsulated and then it has epithelial covering.

• It has follicle and CRYPTS, supported by trabeculae.

• The epithelial covering separate from underlying tissue. Stratified squamous epithelial.

Palatine Tonsil

• The epithelial covering is from stratified squamous.

• We won’t see salivary gland or skeletal muscle in palatine tonsil.

Pharyngeal Tonsil

• DOES NOT HAVE CRYPT• There is follicle • Epithelial lining consist

of pseudostratifiesd ciliated columnar.

Lymphatic nodule in small intestine

• We can see villi covered with simple columnar epithelial in ileum of GIT.

• Here we have goblet cell, muscle layer and Peyer’s Patches.

• This slide shows a cancer cell. apply your knowledge about connective tissue, these cells doesn’t have proper intercellular junction. Therefore, they may slip away into the lymphatic drainage. The 1st thing that drain the cell is the vein, but since it is a large substance, we need lymphatic vessel to drain.

• This slide shows a trabeculae. The blue cells you see is lymphoid tissue around the blood vessel. It is to clear it from lets say, bacteria. SO we need macrophages and lymphocytes.

• Note that the central artery will give branch into pericillar artery.

• How do we know it is a lymphocyte?

• Lymphocyte = larger nucleus + something dark in nucleus + good amount of cytoplasm.

• This dilated capillary is sinusoid. Macrophages gives out appendages. They catch and take out bad RBCs.

Red Pulp Vs White Pulp

• Again about red pulp and white pulp.

• Red pulp = sinusoid + phagocytic cells around it

• White pulp = central artery + lymphoid tissue around it

• Splenic cord = macrophages around the sinusoid

• Lymph node has fibrous skeleton, reticular strand, lymphoid tissue and sinuses. Of course we need T-lymphocytes here, so the cells are brought there by the circulation. There’s a good number of plasma cells in the medulla and these come from B-lymphocytes.

• Note : only lymph node has SUBCAPSULAR SPACE

• How do we know whether it is a blood vessel or lymphatic vessel? It has thin wall, no RBCs in the lumen and we can see clear fluid with some neutrophils or lymphocytes.

• Note that the yellow colour here is due to dye usage

• Note where the lymph nodes are situated. In investigating a breast cancer, it is not enough to say your patient is OK simply by examining the palpable lymph nodes such as the axillary lymph node. There’s also supraclavicular lymph nodes and retrosternal lymph nodes which are not palpable.

• We do mammogram to diagnose a breast cancer. #1 The lymph nodes size are irregular and see this fiber #2, we don’t find this appearance anywhere else in the breast. This tell us that it is abnormal.

• The CT scan shows us the abnormal retrosternal lymph node. [refer to arrows]. The vertebra we see here is cervical, we can recognize this from the transverse foramen and the shape of the spinal foramen.

• For lung cancer, we use endoscope and there is an ultrasound technology in the scope that will give us the images of the lymph nodes.

• For prostate cancer, they are drained by internal iliac lymph node.

• There are only 3 areas where swollen gland occurs : neck, axilla and groin area.

• From this slide we know the location of spleen in our body. It is in hypochondriac region, between 9th and 11th ribs, posterior.

• This is something we will see often in our life as a doctor. This patient has pus formation in the palatine tonsils. This is a huge amount of pus. How do we know this? Remember that we said palatine tonsils have crypts? So, if we can see pus outside, nearly the whole crypts are full of it.

• Thymus is located posteriorly. It will disappear when we grow old. It is like an academy, it teaches the lymphocytes. When there is no need to train new lymphocytes, it will close down. When we’re one year old or so, we have already graduated the T-lymphocytes.