الفهرس 
Introduction and Aim of the work
• Histology and development of placentaOnly 14 pages are availabe for public view
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Abstract
Background:Placenta provides the means for physiological exchange of blood gases, nutrients and wastes between the fetal and the maternal circulation. Normal fetal growth and survival depend on the proper placental development and function. Preeclampsia is a condition characterized by hypertension and proteinuria after 20th week of gestation.
Aim of the work: This study was designed to investigate the role of VEGF and NK cells in histological changes in pre-eclamptic placentae.
Subjects and methods:A total of 60 placental specimens were collected from 3rd trimester deliveries. Placental tissues were divided into two study groups, 20 specimens from normal pregnancies and 40 specimens from pregnancies complicated by pre-eclampsia. Paraffin sectionswere stained with Hematoxylin and Eosin, Masson’s Trichrome and Immunohistochemically for VEGF-A and CD56. Quantitative morphometeric studies followed by statistical analysis of the data were done.
Results: Light microscopic examination showed that syncytial nuclei were aggregated into knots with the presence ofsprouts and strands. Villous connective tissue core was condensed with apparentlydecreased fetal capillaries. Masson’s trichrome stained sections revealed the villous core filled with thick collagen bundles with a significant increase in the thickness of the wall of fetal vessels. Immunohistochemically, VEGF-Aimmunoexpression and CD56 +ve NK cellswere significantly higher in placental biopsies from pre-eclamptic patients when compared to that of the control.
Conclusion:In pre-eclampsia tissue hypoxia occurs leading to an increase in Natural Killer cells which produce angiogenic factors including VEGF to compensate ischemia and hypoxia via neoangiogenesis.