Placenta Histology Flashcards
(26 cards)
What are the things required for Implantation and Placenta formation?
Endometrial invasion. Secretory phase endometrium required. Trophoblast proliferation (lacunar formation, contact with uterine venous sinuses). Uterine epithelium regeneration. Decidual reaction.
What are the components of the chorionic villi?
Extra embryonic mesoderm, cytotrophoblast, syncytiotrophoblast, blood vessels
What is a Primary villi?
Trophoblast only (syncytiotrophoblast (outside), cytotrophoblast (inside)). No extra embryonic mesoderm or blood vessels yet.
What is a Secondary villi?
Mesodermal ingrowth into core of primary villus. Branching occurs. Three parts: Syncytiotrophoblast (outer), Cytotrophoblast, Mesodermal core (inner)
What is a Tertiary villi?
Differentiation of blood vessels in the mesodermal core of a secondary villus. Anastomosis of villa blood vessels with fetal circulation.
What are Anchoring Villi vs Free Villi?
All tertiary villi. Cytotrophoblastic shell formation (invasion of cytotrophoblast through syncytiotrophoblast, Cystotropoblast makes direct contact with decidual cells in endometrial stroma). Anchoring villi are connected to shell. Free villi are not connected to shell.
What is the decidual reaction?
Transformation of endodermal stromal cells (swell due to glycogen and lipid accumulation, transformation spreads throughout superficial layers of endometrium). Occurs during each menstrual cycle and is enhanced after implantation.
What are the three placental components?
Decidua basalis, Decidua capsularis, Decidua parietalis
What is the Decidua basalis?
Between conceptus and myometrium. Constitutes maternal portion of placenta. Site of decidual reaction and most extensive villi invasion.
What is the Decidua capsularis?
Between conceptus and uterine lumen. Becomes attenuated as the embryo grows and eventually regresses.
What is the Decidua parietalis?
Remainder of endometrium.
What are Cotyledons?
Adjacent to the decidua basalis. Placenta divided into 15-30 lobules by septae from decidua basalis. Each cotyledon contains 2-4 tertiary villi and their branches.
What is the route of fetal circulation?
Fetus drains to umbilical arteries, to chorionic arteries to villar capillaries, to chorionic veins, to umbilical vein, to fetus
What is the route of maternal endometrial circulation?
Maternal blood to spiral arteries, to intervillous space, to endometrial veins.
How many arteries and veins are in the umbilical cord?
2 arteries (go to mom), 1 vein (goes to fetus), in relation to fetal heart
What are Hofbauer cells?
Large cells in extra embryonic mesoderm that are macrophages with large single cells located in the mesoderm.
What is the placental barrier like in the first trimester?
Syncytiotrophoblast, Cytotrophoblast, Basal lamina of trophoblast, Fetal connective tissue (extra embryonic mesoderm), Basal lamina of fetal capillaries, Fetal endothelium
What is the placental barrier like after twenty weeks?
Cytotrophoblast progressively disappears and connective tissue (extra embryonic mesoderm) thins. Barrier then becomes Syncytiotrophoblast (thin and few), Basal laminae, Fetal capillaries
What is are the TORCH pathogens?
Things that can cross the placental barrier. Toxoplasmosis, Other (Parvo B19, Syphillis, VZV), Rubella, Cytomegalovirus, Coxsackievirus, HIV, Hepatitis B, Herpes simplex virus
What are the main placental hormones?
HCG, Progesterone, Estrogen, Human placental lactogen (hPL), Prolactin, Prostaglandins, Relaxin
What is HCG?
Human chorionic gonadotropin. Peptide produced by syncytiotrophoblast. Helps maintain corpus luteum and its production of progesterone and estrogen. Presence in maternal urine used for pregnancy tests. Present 6 days after fertilization.
What is Progesterone?
By end of first trimester, progesterone secretion is sufficient to replace that produced by corpus luteum. Produced by syncytiotrophoblast.
What is Estrogen?
Fetal adrenal gland produces androgen. Androgen converted to estrogen by syncytiotrophoblast.
What is Human placental lactogen (hPL)?
Chorionic somatomammotropin (HCS). Peptide produced by syncytiotrophoblast. Affects growth, lactation, lipid and carbohydrate metabolism.
