Fetal Development and Membranes

Vocabulary flashcards covering fetal development, fetal membranes, placental structure and function, amniotic fluid, umbilical cord, yolk sac, twins, birth defects, and prenatal diagnosis.

Decidua

The endometrium after implantation of the blastocyst.

Decidua basalis

The part of the decidua that lies over the embryonic pole of the chorionic vesicle.

Decidua capsularis

The part of the decidua that covers the abembryonic pole of the chorionic vesicle.

Decidua parietalis

The part of the decidua lining the rest of the uterine cavity.

Chorion

The wall of the chorionic vesicle, consisting of the trophoblast and somatopleuric mesoderm.

Chorionic villi

Projections from the chorion, classified as primary, secondary, and tertiary, that facilitate nutrient exchange.

Chorion frondosum

The part of the chorion where the chorionic villi over the embryonic pole become numerous and well developed.

Chorion laeve

The part of the chorion where the villi degenerate by the end of the 3rd month.

Placenta

A vital organ of connection between the fetus and the mother, allowing exchange of material between fetal and maternal blood.

Cotyledons

Slightly elevated areas on the maternal surface of the placenta, divided by grooves, numbering between 15 and 20.

Placental Barrier

The layers of the villous wall that separate fetal blood from maternal blood, facilitating exchange while preventing mixing.

Amnion

The membrane that bounds the amniotic cavity and is continuous with the ectoderm at the amnio-ectodermal junction.

Amniotic fluid

Clear, watery fluid composed mainly of water, electrolytes, proteins, carbohydrates, lipids, phospholipids, and urea.

Polyhydramnios

An excess of amniotic fluid, typically more than 1,500 to 2,000 mL.

Oligohydramnios

A decreased amount of amniotic fluid, typically less than 400 mL.

Amniotic Bands

Tears in the amnion that may encircle part of the fetus, leading to amputations, ring constrictions, and other abnormalities.

Umbilical Cord

Connects the fetus to the placenta, contains the umbilical arteries and vein, and is surrounded by Wharton's jelly.

Yolk Sac

A sac that replaces the blastocele on the ventral surface of the embryonic disc and is important for early blood cell and germ cell formation.

Dizygotic twins

Twins that result from simultaneous shedding of two oocytes and fertilization by different spermatozoa.

Monozygotic twins

Twins that develop from a single fertilized ovum and result from splitting of the zygote at various stages of development.

Birth defect

Structural, behavioral, functional, and metabolic disorders present at birth.

Teratogens

Factors that cause birth defects.

Malformations

Abnormalities that occur during the formation of structures (during organogenesis).

Deformations

Abnormalities due to mechanical forces that mold a part of the fetus over a prolonged period.

Disruptions

Morphological alterations of already formed structures caused by destructive processes.

Syndrome

A group of anomalies occurring together that have a specific common cause.

Association

The nonrandom appearance of two or more anomalies that occur together more frequently than by chance alone, but whose cause has not been determined.

Ultrasonography

A prenatal diagnostic technique using sound waves to visualize the fetus and assess its growth and development.

Amniocentesis

A prenatal diagnostic procedure involving the withdrawal of amniotic fluid for biochemical and genetic analysis.

Chorionic villus sampling

A prenatal diagnostic procedure involving the aspiration of chorionic villus tissue for genetic analysis.