Endoreduplication in cervical trophoblast cells from normal pregnancies

Area of Science:

• Reproductive biology
• Cellular biology
• Prenatal diagnostics

Background:

• Fetal cells, specifically extravillous trophoblasts (EVTs), are crucial for early prenatal diagnosis.
• Endoreduplication, a process leading to polyploidy, may indicate increased cellular metabolic activity.
• The prevalence of polyploid trophoblasts in the cervix during early gestation requires further investigation.

Purpose of the Study:

• To determine the normal prevalence of polyploid trophoblasts exfoliated to the cervix between 5 and 13 weeks of gestation.
• To investigate potential differences in polyploid trophoblast rates between male and female fetuses.

Main Methods:

• Cervical samples were collected using a cytobrush from 36 singleton pregnancies (5-13 weeks gestation).
• Fluorescence in situ hybridization (FISH) was performed using X, Y, and chromosome 21 probes.
• Tetraploid cells (endoreduplicated trophoblasts) were quantified and compared to normal cervical cells.

Main Results:

• Twenty-one pregnancies had female fetal karyotypes and 15 had male fetal karyotypes.
• A mean of 15.2 (0.02%) tetraploid cells were found in pregnancies with female fetuses.
• A mean of 2.0 (0.003%) tetraploid cells were found in pregnancies with male fetuses; these cells were larger than normal.

Conclusions:

• Extravillous trophoblasts commonly undergo endoreduplication, reaching 4c-8c DNA ploidy levels.
• This endoreduplication appears to be a typical phenomenon in the developing placenta.
• Higher rates of endoreduplication in extravillous trophoblasts were observed in pregnancies with female fetuses.