Embryo resides between the red marks
Yolk sac is ventral to the embryo.
Chorionic cavity is black.
x indicates length of embryo
5-week-old embryo:
Upper limbs are visualized in the Coronal scan
Embryo is surrounded by a thin amnion
Chorionic cavity contains a fluid that is more particulate than the amniotic fluid
x indicates length of embryo
7-week-old embryo:
Eye, limbs, fourth ventricle (arrow) of brain are seen in a sagittal section
x indicates length of embryo
Embryo in the early part of the ninth week (1)
Amniotic cavity (2)
Extrafetal or chorionic cavity (3)
Amnion (4)
Sonogram of abnormal embryos
Early second trimester of pregnancy:
Fetus with meroanencephaly (coronal surface): Absence of the calvaria superior to the orbits (O)
Fetus with anencephaly (sagittal surface): A large angiomatous tissue (arrows) cephalad to the base of the skull
Transvere sonogram: Sacrum in a fetus with a myelomeningocele. Arrows point to the abnormal posterior ossification centers
Longitudinal sonogram: Myelomeningocele protruding from the vertebral column. The spinal cord ends at an abnormally low level.
Sac of the myelomeningocele in contact with the amniotic fluid (arrows). Arrowheads point to the lack of contact with the placental surface
4.5-week-old embryo:
Embryo resides between the red marks
