When nondisjuction occurs during an early cleavage division of a zygote and an embryo with two or more cell ines with different chromosome complements is produced
Preimplantation genetic diagnosis can be carried out how many days after in vitro fertilization of an oocyte?
3 to 5 days
Early implantation of the _____ is a critical period of development that may fail to occur
Overall early spontaneous abortion rate
More than half of all known spontaneous abortions occur because of abnormalities in what?
When blastocysts implant outside the uterus
95% to 98% of ectopic implantations occur where?
uterine tubes (more often in ampulla and isthmus)
pocket formed by the deflection of the peritoneum from the rectum to the uterus where blastocysts can commonly implant
a calcified fetus
the placenta becomes firmly attached to fibrous and muscular tissues of the cervix
implantation of a blastocyst in the inferior segment of the uterus near the interal os (opening) of the cervix results in what?
placenta pervia (placenta that particually or completely covers os)
early pregnancy loss
most spontaneous abortions ob embryos occur during the first ___ weeks
The higher incidence of early spontaneous abortions in older women probably results from the increasing frequence of?
nondisjunction during oogenesis
Relatively large doses of progestins and/or estrogens ("morning after pill") usually does not prevent fertilization but often prevents what?
implantation of the blastocyst
A high dose of diethylstilbestrol does what?
accelerates the passage of the cleaving zygote along the uterine tube
An intrauterine device usually interferes with implantation by causing what?
a local inflammatory reaction
Symptom of pregnancy?
remnants of the primitive streak may persist and give rise to a _________
type of germ cell tumor
benign and malignant tumors that form from vestigial remnants of notochordal tissue
remnants of the extraembryonic portion of hte allantois
partial absence of the brain (neural tube defect)
cystic swellings formed from degenerating chorionic villi
malignant trophoblastic lesions