Lymphatic Tissues and Organs

February 15, 2010

Lymphatic System

Lymphatic vessels:Removes extracellular fluid (lymph) from the lamina propria.Absorb fat and transport as chyle. Transport lymphocytes and other cells, such as tumor cells.

Lymphatic tissues:Diffuse lymphatic tissues and cells

Solitary nodulesAggregates of nodules (Peyer’s patches) Tonsils Lymph nodes (filters lymph) Spleen (filters blood) Thymus (T cell differentiation) Bone marrow (source of lymphocytes)

Ross and Pawlina, p.397

Ross and Pawlina, p. 417

#27 Lymph node

Cortex

Medulla

Hilu

s

#26 Lymph Nodealso #142

Subcapsular sinus

Trabecular sinus

Medullary sinuses

Hilus

Efferent lymphatic ducts

Blood vessels

Secondary follicles

Medullary cords

Direction of lymph flow through a

lymph node

Afferent lymphatic vessel

Subcapsular sinus

Trabecular or perinodular sinus

Medullary sinus

Efferent lymphatic vessel

Thoracic duct

Left subclavian vein

General circulation

Ross and Pawlina, p. 419

To lymph nodes

(Left side)

Another lymph node….

#26 Lymph Node: secondary follicle

Germinal center: lymphoblasts

HEV

Subcapsular sinus

#26 Lymph Node: Medullary cords and sinuses (also #142)

M. Cord: lymphocytes plasma cells

M. sinus reticular cells lymphocytes macrophages

#30 Lymph Node

Afferent lymphatic ducts

#30 Lymph Node: deep cortex

High Endothelial Venules

High endothelial venules: longitudinal sections

#142 Lymph Node H&E

#28: silver stain Reticular fibers in medullary sinus

Solitary nodules #161 &157

Aggregates of nodules

#175, UCSF 261, 168

#161

#261

#168 (jejunum) Intraepithelial lymphocytes

Palatine tonsil: covered with stratified squamous epithelium which invaginates to line the surface of the crypts

Ross and Pawlina, p. 415

#138L Palatine tonsil

crypt

crypt

Stratified squamous epithelium

#138 Palatine tonsil: starry sky

Macrophages

Lingual Tonsils

Spleen: red and white pulp#147B #148, #301

#301

Splenic Circulation

Splenic artery Splenic vein

PALS: Periarterial (periarteriolar) lymphatic sheath

Ross, et al. 13-31

#301 Splenic nodule (2o) and central artery

Germinal

center

Germinal

center

#148 PALS and Marginal zoneGreen arrows: macrophage

#148 Splenic sinuses

Splenic sinuses

Ross and Pawlina, p. 427

Pulp vein trabecular vein splenic vein

#301

#147B Human Spleen, H&E

#26 Lymph Nodes #140 Thymus

Incomplete lobules: The medulla of adjacent lobules merges.

#27 Lymph Node #140 Thymus

No follicles in the cortex

#140 Thymus: medulla

Epithelial reticular cells

Hassall’s corpuscle

Blood vessel

#140 Young Thymus #141 Involuting Thymus