PRENATAL DEVELOPMENT OF THE POST-CAPILLARY VENULES IN HUMAN LYMPHATIC TISSUE

K Syrjanen

Abstract


Lymph nodes, Peyer's patches and tonsils from 19
human fetuses or stillborn babies between 13 and 40
weeks of pregnancy were collected, and their post-ca pillary
venules (PCV) were subjected to direct mor·
phometric measurements. The aims were to gain information
about their development as well as about the
circumstances of lymphocyte recirculation during the
fetal period.
First PCV:s detectable in fetuses aged 15 weeks had
a low endothelium (2 .3 to 3.2 1-1m), which increases
in heigth thereafter, up to 10.1 1-1m in full-term pregnancies.
This increase was not directly related to gestational
age, however, but correlated most closely
with the state of supposed lymphocyte traffic, as defined
on morphological grounds.
The results suggest that active lymphocyte recirculation
is established in fetal period, and because of ab sence
of external antigenic stimuli it must be an inherent
property of lymphocytes acquired by them
during the second trimester.


Full Text:

PDF