RT Book, Section
A1 Longo, Dan L.
A2 Longo, Dan L.
SR Print(0)
ID 1135229353
T1 Thymoma
T2 Harrison's Hematology and Oncology, 3e
YR 2016
FD 2016
PB McGraw-Hill Education
PP New York, NY
SN 9781259835834
LK hemonc.mhmedical.com/content.aspx?aid=1135229353
RD 2024/04/19
AB The  thymus  is  derived  from  the  third  and  fourth  pharyngeal  pouches  and  is  located  in  the  anterior  mediastinum.  It  is  composed  of  epithelial  and  stromal  cells  derived  from  the  pharyngeal  pouch  and  lymphoid  precursors  derived  from  mesodermal  cells.  It  is  the  site  to  which  bone  marrow  precursors  that  are  committed  to  differentiate  into  T  cells  migrate  to  complete  their  differentiation.  Like  many  organs,  it  is  organized  into  functional  regions,  in  this  case  the  cortex  and  the  medulla.  The  cortex  of  the  thymus  contains  ~85%  of  the  lymphoid  cells,  and  the  medulla  contains  ~15%.  It  appears  that  the  primitive  bone  marrow  progenitors  enter  the  thymus  at  the  corticomedullary  junction  and  migrate  first  through  the  cortex  toward  the  periphery  of  the  gland  and  then  toward  the  medulla  as  they  mature.  Medullary  thymocytes  have  a  phenotype  that  cannot  be  distinguished  readily  from  that  of  mature  peripheral  blood  and  lymph  node  T  cells.