Implantation and Fetal Membranes Flashcards
describe what the enzyme vesiculase does
- coagulates semen to form a plug at the externa os which prevents backflow of semen into the vagina
implantation of ____ begins on day ____ and ends on day _____
implantation of blastocyst begins on day 5/6 and ends on day 10
1 = endometrium
2 = hypoblast
- synctiotrophoblast
4 = cytotrophoblast
5 = epiblast
the usual site of implantation is….
the usual site of implantation is the posterior wall of body of uterus close to the fundus
name 2 enzymes the synctiotrophoblast secretes
- proteolytic enzymes to erode endometrium and blastocyst burrows into endometrial CT
- also secretes hCG which maintains the corpus luteum
describe pregnancy tests
- tests for hCG in maternal urine at end of 2nd week after conception
- test for presence of early pregnancy factor (EPF), an immunosuppressant protein which appears in maternal serum 24-48 hours after conception
equation for calculating expected date of delivery (EDD)
Date of last menstrual period + 9 months + 7 days (Naegele’s rule)
describe Hydatiform mole (H-mole)
- A molar pregnancy starts when an egg is fertilized, but instead of a normal, viable pregnancy resulting, the placenta develops into an abnormal mass of cysts.
- little to no embryonic tissue present
- trophoblast develops well
- hCG produced
- may give rise to choriocarcinoma
describe the primary yolk sac or exocoelomic cavity
- first site of blood formation
- gives rise to the primordial gut
- primordial germ cells arise in the endodermal lining of the yolk sac
describe the allantois
- arises as a diverticulum from the yolk sac and extends into the body stalk
- another early site of blood formation
- its blood vessels form the umbilical arteries and veins
- obliterates and forms the urachus (median umbilical ligament postnatally)
describe the function of aminiotic fluid
- shock absorber
- maitains constant temp
- lung development
- symmetrical growth
- antibacterial activity
the aminion fuses with ____ ____ and obliterates the _____ _____ forming the single ______ membrane
the aminion fuses with chorion wall and obliterates the chorionic cavity forming the single amniochorionic membrane
describe oligohydramnios and potential causes
- low volume of amniotic fluid
- causes:
- preterm rupture of amniochorionic membrane
- urinary system anomalies
- renal agenesis
- placental insufficiencies
- decreased blood circulation
- complications
- lung hypoplasia
- facial or limb deformities because less space to grow
describe polyhydramnios and causes
- high amniotic fluid volume
- causes:
- idiopathic
- maternal
- multiple pregnancies
- maternal diabetes
- fetal
- esophageal atresia
- meroencephaly
- anencephaly
- complications
- preterm labor and delivery
describe amniotic band syndrome
- aminotic bands can amputate the limbs
describe the components of the chorion wall
- syncytiotrophoblast
- cytotrophoblast
- somatic layer of primary mesoderm
contast smooth chorion and villous chorion
- smooth chorion = chorion sac enlarges toward the uterine cavity and the villi on that part degenerate
- villous chorion = villi on the chorion sac towards the uterine wall grow and become bushy
name the 3 layers of the decidua
- decidua basalis is the endometrium deep to the chorion in contact with villous chorion
- decidua capsularis is the endometrium related to the smooth chorion and it separates it from the uterine cavity
- decidua parietalis refers to the rest of endometrium not directly related to the chorion sac
describe placental abnormalities
- placenta accreta
- abnormal adherence of placenta (chorionic villi) to the uterine wall
- placenta percreta
- placenta penetrates the entire uterine wall
- 3rd trimester bleeding
- placenta previa
- placenta bridges the cervical opening
- severe bleeding in later part of pregnancy
describe amniocentesis
- sampling of the aminiotic fluid for karyotyping and levels of enzymes
- performed in 2nd trimester
- low relative risk
describe chorionic villus sampling
- biopsy of chorionic villi
- can be performed as early as 7 weeks
- detects chromosomal abnormalities, inborn errors of metabolism
- riskier than amniocentesis
describe alpha-fetoprotein assays
- glycoprotein synthesized in fetal liver and umbilical vesicle
- increase: neural tube defects
- decrease: Down syndrome
describe dizygotic twins
- most common type
- origin from 2 zygotes
- fertilization of 2 oocytes by 2 sperms
- 2 amnions and 2 chorions
- placentas may be fused
describe monozygotic twins
- origin from a single zygote
- genetically identical and same sex
- division of embryoblast into 2 embryonic primordia
- 2 amniotic sacs
- 1 chorionic sac
- 1 placenta
describe twin transfusion syndrome
- preferential shuting of arterial blood in one twin to venous blood in the other
- donor twin = small and anemic
- recipient twin = large and polycythemic
describe conjoint twins
- incomplete division of the embryonic disc
