The Placenta
Contents
Thickness of placenta increases up to
A. 12th week
B. 16th week
C. 28th week
D. 34 th week
Not true of placenta
A. Majority of the placenta is a specialized part of the chorion
B. Decidual septum which is derived from the basal plate
C. Blood in the intervillous space is of maternal origin
D. The line of separation is through the decidua vera
Not a part of Chorionic plate
A. Primitive mesenchymal tissue
B. Nitabuch’s layer
C. Cytotrophoblast
D. Syncytiotrophoblast
Placentome is
A. Functional unit of placenta
B. Primary stem villi
C. Nutritive villi
D. Other name of decidual septa
Not true of Hofbauer cells
A. Round cells that are capable of phagocytosis
B. Immunomodulant cells
C. Found in central stroma of terminal villi
D. Express class II major histocompatibility complex (MHC) molecules
Morbid adhesion of placenta is prevented by
A. Endovascular trophoblasts
B. Interstitial trophoblasts
C. Natural Killer cells
D. Myometrial smooth muscle
Not true of umbilical vein circulation is
A. O2 saturation – 70-80%
B. Pressure in the umbilical vein – 10 mm Hg
C. PO2 – 30–40 mm Hg
D. Obliteration of the right umbilical vein occurs in the second trimester
In shorts
- The fetal venous system develops from three embryological paired veins; the vitelline veins from the yolk sac, the umbilical veins from the chorion and the cardinal veins from the embryo.
- Obliteration of the intra‐abdominal umbilical vein at birth produces a hepatic remnant termed the ligamentum teres.
- The allantois arises as a diverticulum of the yolk sac extending from the early fetal bladder into the body stalk and contributes to umbilical vessel development. The intra‐abdominal remnant of the allantois involutes to a thick tube termed the urachus or the median umbilical ligament.
- The thick “beta zones” of the terminal villi with the layers remaining thick in patches are for hormone synthesis.
- There may be inconsistent deposition of fibrin called Rohr’s stria at the bottom of the intervillous space and surrounding the fastening villi.
- The striae of Rohr, Nitabuch, and Langhans appear to have the biologic sense of a peripheral fibrinoid barrier resulting in the effort to arrest the trophoblastic invasive proliferation by the same general process of cellular necrosis.
