Decidua, chorion, placenta, umbilical cord. Doc. MUDr. Marie Jirkovská, CSc. Institute of Histology and Embryology

Decidua endometrium in pregnancy- decidua basalis - pars materna placentae schema secretory phase decidual cells

Chorion Decidua basalis B.M.Carlson: Human Embryology and Developmental Biology, 1999 Decidua basalis

Chorionic villi primary (P) secondary (S) tertiary (T) syncytiotrophoblast cytotrophoblast S P capillary P Hofbauer‘s cells

Chorion S - syncytiotrophoblast, C - cytotrophoblast, M - mesenchyme, H - Hofbauer cells

Chorionic villi *proliferation and migration of cytotrophoblast, C – cytotrophoblast shell, V – chorionic villus, D - decidua V V * C C * D

Relationship of decidua and chorion

Human placenta at term maternal part (decidua basalis) cotyledons Discoid (diameter 15 – 20 cm, thickness 2 – 3 cm) – according shape Hemochorial villous – according structure Placenta consists of: fetal part (villous chorion) and maternal part (decidua basalis) cotyledons

Human placenta at term – a scheme Fetal part: chorionic plate and cotyledons consisting of one or more main stem villi and their branches. Maternal part: decidual plate is covered by syncytiotrophoblast, contains decidual cells and remnants of the cytotrophoblastic shell.

Placenta at low magnification

Stem and intermediate villi Fibrinoid – eosinophilic mass on the surface of villi, decidua basalis and chorionic plate (material composed of fibrin from maternal blood and degenerated cells).

vasculosyncytial membrane Placenta Terminal villi Placental septum vasculosyncytial membrane syncytiotrophoblast cytotrophoblast decidual cell capillary

3-D reconstruction of the villous capillary bed

Umbilical cord length cca 50 cm A – a. umbilicalis, V – v. umbilicalis, E – ectoderm of the amnion, W – Wharton‘s jelly E W V A W V A E