Volume 13, No 4, Aug 2003

ISSN: 1001-0602 
EISSN: 1748-7838 2018 
impact factor 17.848* 
(Clarivate Analytics, 2019)

Volume 13 Issue 4, August 2003: 265-273

ORIGINAL ARTICLES

Kinetics of thymocyte developmental process in fetal and neonatal mice

Shi Yun XIAO*, Yan LI*, Wei Feng CHEN**

Department of Immunology, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100083, China Correspondence: Wei Feng CHEN(wfchen@public.bta.net.cn)

Kinetics of thymocyte development in vivo during
embryogenesis was pursued. The early development of thymocytes in the
fetal and neonatal BALB/c mice was discontinuous, with four waves of cell
proliferation occurring at fetal day (Fd) 14 to 17, Fd 18 to day (D) 1
after birth, D 2 to D 5 and D6 thereafter. The first three proliferation
waves coincided with the generation of CD4^hiCD8^hi
(DP), TCR⁺CD4^hiCD8^->/lo (CD4 SP), and TCR⁺CD4^->/loCD8^int/hi (CD8 SP) thymocytes, respectively. The transition
from DN to DP cells was further investigated and it was found out that
there were two differential pathways via immature single positive (ISP)
cells in the BALB/c mice, each functioning at different fetal ages. One
is via TCR^->CD4^->CD8⁺ cells, occurring between Fd 15 and Fd 17 and the other
is via TCR^->CD4⁺CD8^-> cells, occurring from Fd 17 until birth. In contrast, the TCR^->CD4^->CD8⁺ pathway dominated overwhelmingly in the C57BL/6 mice. These
findings shed new light on the hypothesis that the differential pathway
preference varies with mouse strains. With respect to the shift in the
intensity of CD4 and CD8 expression on thymocytes from fetal to adult
mice, the TCR⁺CD4^hiCD8^->/lo, and TCR⁺CD4^->/loCD8^int/hi subsets might be equivalent to the medullary type
TCR⁺CD4/CD8 SP cells.

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