Development of the immune system

✍ Scribed by Anne Durandy

• Publisher: Hindawi Publishing Corporation
• Year: 1997
• Tongue: English
• Weight: 215 KB
• Volume: 5
• Category: Article
• ISSN: 1064-7449
• DOI: 10.1002/(sici)1098-0997(1997)5:2<93::aid-idog2>3.0.co;2-8

✦ Synopsis

T he development of immune defense mecha- nisms begins early during fetal life but is not completely achieved at birth, leading to a peculiar susceptibility of the neonate to infectious diseases. 1,2 The earliest hematopoietic stem cells are detectable in the yolk sac around 6 weeks of gestation, but at that time they are only able to differentiate into myelomonocytic cells. Thereafter, the hematopoiesis takes place in the liver from the 7th week of gestation until the 6th month, thereafter in the bone-marrow. A unique precursor is at the origin of all hematopoitic cell lines.