Lecture 21 lymphoid organs Flashcards
whats the difference between lymph vessels and blood vessels?
- more permeable than blood capillaries and pick up excess interstitial fluid
- have thinner walls, no basement membrane, more valves and have lymph nodes along the way
- not present in the brain, spinal cord, or bone marrow
whats the difference between lymph and chyle?
Lymph- same as interstitial fluid and plasma
-clear, slightly yellowish and opalescent fluid.
Chyle-in intestines, milky from absorbed fat
What is diffuse?
unorganized collection of lymphocytes
what is Nodular?
- always surrounded by diffuse tissue
- more organized
- germinal center
what is the internal structure of lymph nodes?
- surrounded by fibrous capsule, extends internally to form trabeculae
- outer cortex contains follicles
- inner medulla
- reticular network
- formed by reticular fiber & elastins
- subscapsular sinus is deep to the capsule
-endothelium is continuous with afferent lymph vessel.
whats the path lymph node takes as it drains from afferent to efferent lymph vessels?
- subscapular sinus drains to travecular sinuses
- cortical sinuses and traveculae sinuses drain into medullary sinus
- lymph flows out of medullary sinuses via the efferent lymph vessels
What are the germinal centers and what organs are they found in?
- nodular lymphatic tissue
- clone of B-lymphocytes
- site of antibody production
- Present in the spleen “PALS”
what recieves lypmh from the lumbar and visceral trunks and drains the lymph nodes of the abdomen, pelvis and pelvic limb?
Cisterna chyli
where is the spleen located?
upper left region of the abdomen
Major lymphatic vessels draining the entire body except right thoracic limb, right crainial thorax and right side of neck.
It empties near thoracic inlet into the jugular vein or caudal vena cava.
Thoracic duct
Drains right cranial thorax, right thoracic limb and right side of the neck into the venous system where the caudal vena cava is formed.
Right lymphatic duct
What are the 3 principle cell types in the thymus?
- thymocytes
- macrophages
- epithelio-reticular cells
consists most of the spleenic pulp, acts as a filter, many fixed macrophages. mostly red because blood is held within it.
Red pulp
White areas form nodules and sheaths of lymphocytes around arteries and arterioles (PALS).
white pulp
“PALS”, place where special conditions require for proliferation of B-lymphocytes can be met. Its found in the spleen.
Periateriolar lymphocyte sheaths
Its a concentric mass of epithelial cells only present in the thymus of mammals.
Hassal’s corpuscles
Drains the ventral part of the head
mandibular lymph node
drains the dorsal part of the head
parotid lymph node
drains deeper structures of the head and neck
retropharyngeal lympho center
(prescapular)- located in front of shoulder joint, drains superficial neck, dorsal thorax, and proximal forelimb.
superficial cervical lymph node
along trachea, drains deep/ventral structures of the neck to the thoracic duct on left side or lymphatic duct on right
deep cervical lymph nodes
located in the axilla, drains forelimb and thoracic wall, drains first three mammary glands in dogs
axillary lymph node
drains the groin, caudal mammary glands and scrotum into iliosacral or deep inguinal lymph node. is present in all species.
superficial inguinal lymphocytes
drains distal limb into medial iliac center. superficial in carnivores deep in other species.
popliteal lymph node
located near the termination of the aorta in the abdominal and pelvic cavities. drains the pelvic organs and hind limb into the lumbar trunks.
Medial iliac and sacral lymph nodes
