Embryo and Histo lymphatics (complete) Flashcards
What are the structures of the lymphatic system
- Lymphatic organs 2. Lymphocytes 3. Lymphatic vessels
What are the three main types of lymphocytes
- T-Cells 2. B-Cells 3. Null Cells
Where do T-Lymphocytes originate from
bone marrow
where do B-Lymphocytes originates from
Bone marrow
Where do all lymphocytes originate from
Bone marrow
Where do T-Lymphocytes mature
the Thymus
Where do B-Lymphocytes mature
Bone Marrow
What are Null Cells
immature Lymphocytes with no cell markers
What do B-Lymphocytes do
They have antibodies that recognize non-self cells, they then bind those antigens then become active and then initiate the creation of antibodies
What two kinds of cells do B-Lymphocytes differentiate into
Plasma cells Memory B cells
What do plamsa cells do
create and secrete antibodies
what do memory B-cells
remain in the circulation and lymph organs and wait to recognize the same antigen for a second
where do you find plasma cells
in lymphoid organs and connective tissue
where do you find memory B cells
in lymphoid organs and in the blood
What happens in a primary immune response
- widespread inflammatory response to a first exposure to a pathogen - you body creates antibodies to fight against the pathogen
what happens in a secondary immune response
- exposure to a pathogen for a second time only causes a small response by the body because the body has already created antibodies to fight it
What is humoral immunity
the type of immunity created by B-Lymphocytes, in which cells don’t mediate the immunity but macromolecules like Antibodies do.
What is cell-mediated immunity
immunity that is created by T-lymphocytes. in which the cells themselves mediate the immunity.
What are the primary lymphoid structures
Bone Marrow Thymus
What distinguishes primary lymphoid structures from secondary lymphoid structures
primary lymphoid structures are the places where immature lymphocytes differentiate and become mature Secondary lymphoid structures are the places where lymphocytes encounter pathogens and do immunity work
What are the secondary lymphoid structures
Lymph nodes and spleen
What are lymphatic vessels
vessels that take plasma/interstitial fluid/lymph from the tissues, through the nodes, and back into the veins
how do the walls of lymph vessles compare to arteries and veins
the walls are much thinner in lymph vessels
what kind of cells line the lymph vessels
endothelial cells
do lymph vessels have valves
yes
what is the purpose of the valves in lymph vessles
they prevent the backflow of lymph
do lymph vessels ever have smooth muscle
yes, but only sparsely in the larger vessels
do lymph vessels have three tunics like the other blood vessels
yes
how do the tunics of lymph vessels differ from those in arteries and veins
there is no distinct division between the three tunics
after a lymph vessel (capillary) picks up lymph from the interstitial space, does it have anything that the lymph runs through prior to making it back into a vein
Yes, lymph nodes
before lymphoid embryogenesis can occur, what must first have occured
formation of the cardiovascular system
why must the cardiovascular system have been formed before we can do lymphoid embryogenesis
because they form from LEC (Lymphatic endothelial cells) that leave from blood vessels
What is the process of development of lymph nodes
- LECs leave the blood vessels 2. those LECs and groups of mesenchyme aggregate to form lymph sacs 3. This forms lymphatic nodules 4. The nodules become surrounded by sinuses, with mesencyhme completing the lymph node 5. Lymphatic cells migrate from mesenchyme, thymus, and bone to fill the sinus’ and forming the lymph node 6. a caspule forms around the lymph node and trabecula invaginate and comparmentalize the lymph node
What are LECs
Lymphatic endothelial cells, cells that leave the blood vessels and initiate the formation of lymphatic tissue
What are lymphatic nodules
conglomerations of lymph tissue, but don’t have the sinuses like lymph nodes
What are the 6 primary lymph sacs
2 jugular lymph sacs 2 iliac lymph sacs 1 retroperitoneal lymph sac 1 cisterna chyli
What is vasculogenesis
the formation of blood or lymph vessels in a place where there were once no vessels
When does vasculogenesis mostly occur
mostly in embryonic phases
What is angiogenesis
one vessel budding or sprouting off of another existing vessel
Which usually happens first in lymphoid embryogenesis angiogenesis or vasculogenesis
vasculogenesis
How many thoracic ducts are there in the lymphatic system
three
What are the three thoracic ducts of the lymphatic system
Right thoracic duct left thoracic duct common thoracic duct
how do the lymphatic thoracic ducts form
the right and left thoracic ducts form as a connection between the jugular lymph sacs and the cisterna chyli. then anastomosis causes the two ducts to combine and form the common thoracic duct.
what is anastomosis
the combining of things
which is the most mature of the thoracic ducts
the common thoracic duct
from where does the spleen form
from an aggregation of mesenchyme in the dorsal mesogastrium
from where does the palatine tonsils form
the 2nd pharyngeal pouch
from where do the tubal tonsils, pharyngeal tonsils, and lingual tonsils form
from aggregations of lymph nodules in the respective locations
how common are congential abnormalities of lymph structures
rare
what are the two types of congenital abnormalities of lymph structures
congenital lymphedema cystic hygroma
what is congenital lymphedema
diffuse swelling in part of the body
what is cystic hygroma
large swelling on the inferiolateral neck with large fluid filled cavities. the jugular lymph sac fails to drain
how positive are the fetal outcomes for those with cystic hygroma
poor
What are the four lymphoid structures we need to be able to identify histologically
lymph nodes thymus spleen MALT
What is MALT
mucosa associated lymphoid tissue
What are the key things to look for histologically when looking at lymph nodes
- bean shaped body 2. dense fibrous capsule 3. trabecula 4. many afferent vessels, one efferent vessel 5. Has a cortex and medulla 6. Germinal centers in the cortex
what are the different parts of a lymph node
- Cortex (outside) 2. Medulla (inside) 3. paracortex (between the two)
What are the key things to look for histologically when looking at the thymus
- No germinal centers 2. Has a cortex and medulla 3. no afferent lymphatic vessels 4. large macrophages 5. Hassall corpuscle (big white swirly thing) 6. thin connective tissue compared to lymph nodes and spleen
What are the main things to look for histologically when looking at the spleen
- thick capsule 2. Red and white pulp 3. trabecula 4. no cortex and medulla 5. has germinal centers
What is the white pulp of the spleen
a location in the spleen near the central artery with abundant B cells
What is the red pulp of the spleen
a blood rich area which is a reservoir for RBCs and platelets
Where do we normally see MALT
epithelium in close proximity to where we eat, breath, or take things in
What is GALT
MALT in the intestines (clumps of lymphatic tissue in the intestines)
what is the name for GALT in the ileum
Peyer’s Patches
What is BALT
MALT in the bronchi and bronchioles
What are key features to look for when identifying MALT histologically
- tube of sorts 2. lymphatic nodules in the wall of the tube
What are key features to look for when identifying tonsils histologically
- Aggregation of lymph nodules 2. Crypts 3. Un encapsulated
What are the four tonsils of the tonsillar ring
- Palatine 2. Tubal 3. Pharyngeal (adenoids) 4. lingual
Which of the following have a capsule Nodes Thymus Spleen MALT (PP) Tonsil
Nodes = Yes Thymus = thin Spleen = Thick Malt = No Tonsil = No
Which of the following have germinal centers Nodes Thymus Spleen MALT (PP) Tonsil
Nodes = Yes Thymus = No Spleen = Yes MALT = Yes Tonsil = Yes
Which of the following have a cortex Nodes Thymus Spleen MALT (PP) Tonsil
Nodes = Yes Thymus = Yes Spleen = No MALT = No Tonsil = No
Which of the following have a medulla Nodes Thymus Spleen MALT (PP) Tonsil
Nodes = Yes Thymus = Yes Spleen = No MALT = No Tonsil = No
Which of the following do lymph nodes have Capsule germinal centers cortex medulla
All
Which of the following does the thymus have Capsule germinal centers cortex medulla
thin capsule no germinal center both medulla and cortex
Which of the following does the spleen have Capsule germinal centers cortex medulla
thick capsule germinal centers no cortex or medulla
Which of the following does MALT have Capsule germinal centers cortex medulla
no capsule, medulla, or cortex it does have germinal centers
Which of the following do tonsils have Capsule germinal centers cortex medulla
Same as MALT no capsule, medulla, or cortex it does have germinal centers
which type of lymphatic tissue is this?

MALT
which type of lymphatic tissue is this?

MALT
which type of lymphatic tissue is this?

Lymph Node
which type of lymphatic tissue is this?

lymph node
which type of lymphatic tissue is this?

Lymph node
which type of lymphatic tissue is this?

Lymph node
which type of lymphatic tissue is this?

Lymph node
which type of lymphatic tissue is this?

Spleen
which type of lymphatic tissue is this?

spleen
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Thymus
which type of lymphatic tissue is this?

Thymus
which type of lymphatic tissue is this?

thymus
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tonsils
which type of lymphatic tissue is this?

tonsil