Morphology and Morphometric Study of Human Placenta

Human placenta, materno-fetal organ, plays a vital role in maternal-fetal physiology with numerous
responsibilities. It is not merely a passive barrier between the maternal and fetal circulations but has
many physiological functions like implantation, recognition of maternal pregnancy, fetal protection
from immune attacks, exchange of respiratory gases, metabolites, nutrients, and waste products as
well as the endocrine function and the metabolism of xenobiotics. Abnormalities in the placenta’s
function can lead to dismal pregnancy outcomes.
The usual human term placenta is about 22 cm in diameter and 2.0 to 2.5 cm thick. It generally weighs
about 475 g. The ratio between placenta weight and birth weight of the newborn. Placentas with less
than 2.5 cm thickness are associated with intrauterine growth retardation (IUGR) of the fetus.
Placentas more than 4 cm thick have an association with maternal diabetes mellitus, fetal hydrops
and intrauterine fetal infections. The full-term, delivered placenta is, in more than 90% of the cases, a
disk-like, flat, round to oval organ. In nearly 10%, it has abnormal shapes, such as placenta bilobata,
placenta duplex, placenta succenturiata, and placenta membranacea. A well-developed placenta
consists of a chorionic plate, which is of embryonic descent and of a basal plate whose essential layer
is the decidua, a derivative of the endometrium. Between these two plates, there is a voluminous
intervillous space. placental examination is necessary to understand the causes of perinatal deaths.
Documentation of findings and submission of tissue for pathologic evaluation based on abnormal
appearance or various maternal clinical disease is mandatory.