Placental apoptosis in discordant twins.
OBJECTIVE
To investigate placental apoptosis in discordant dichorial twins.


METHODS
Placental samples were obtained from 7 third-trimester suitable twins. Discordancy was defined as a >25 per cent difference in newborn birth weight. Light microscopy using hematoxylin and eosin (H&E)-stained paraffin slides and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) methods were used to confirm the incidence of apoptosis. Investigators were blinded to pregnancy outcome.


RESULTS
Both methods revealed that the incidence of apoptosis in the placentas of the smaller fetuses was significantly higher than in placentas of the larger fetuses. The incidence of TUNEL-positive cells in the former was 1.4+/-0.26 per cent: this was significantly higher than the incidence of apoptosis in the placental specimens of the latter (0.9+/-0.07 per cent, P< 0.02 Wilcoxon rank test). The same results were obtained with H&E: the incidence of apoptosis detected in placentas from the former was 1.07+/-0.1 per cent compared to 0.72+/-0.08 per cent in those of the latter (P< 0.02 Wilcoxon rank test).


CONCLUSIONS
Despite similar environment conditions, placental apoptosis is increased in the smaller fetus and thus might play a role in discordancy between twins. Since increased placental apoptosis has also been found in singleton intrauterine growth restriction, this supports the hypothesis that the smaller twin is selectively growth restricted.
Almog
B
B
Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. beny118@hotmail.com
Fainaru
O
O
Gamzu
R
R
Kupferminc
M J
MJ
Sasson
R
R
Gold
R
R
Lessing
J B
JB
Amsterdam
A
A
Many
A
A
D000328:Adult; D017209:Apoptosis; D001724:Birth Weight; D004200:Diseases in Twins; D005260:Female; D005317:Fetal Growth Retardation / Q000473:pathology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D007231:Infant, Newborn; D009929:Organ Size; D010920:Placenta / Q000473:pathology*; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014429:Twins, Dizygotic