Embryology: Week Two

Front 1

During which phase of menstruation does implantation of the blastocyst occur?

Back 1

impantation occurs at d5-7 embryonic age or d 20ish of gestational age this corrilates with the secretory phase of mestration

Front 2

What is an ectopic pregnancy?

Back 2

an ectopic pregnancy is when the embryo implants anywhere other than the uterus. These pregnancies are usually not viable and usually are terminated for the welfare of the mother. Ideally the embryo implants in the superior posterior portion of the uterus

Front 3

What are the two layers generated by differentiation of trophoblasts?

Back 3

the cytotorphoblast and the syncocytotrophoblast

Front 4

True or False: There are distinct cell boundaries in the syncytiotrophoblast.

Back 4

fasle- the syncocytotrophoblast is a multinucliated layer which actively invades the uterus during implantation. Additoinally it is responsible for production of the hHG whish maintains the uterus lining though actions exerted on the CL and are the basis of pregnancy tests

Front 5

What hormone is targeted by pregnancy tests?

Back 5

hHG

Front 6

What structure forms from the primordial cavity that appears on the embryonic pole between the embryoblast and the cytotrophoblasts?

Back 6

The primordial cavity becomes the amnion the layer below is called the epiblast and is the source of all of the human body

Front 7

Name the two layers of the bilaminar embryonic disk.

Back 7

epiblast and hypoblast

Front 8

Name the membrane developed from migration of hypoblastic cells.

Back 8

primary yolk sac membrane

Front 9

Which is the definite yolk sac, the primary yolk sac or the secondary yolk sac?

Back 9

the definite yolk sac referes to the secondary yolk this forms as the chorinoic cavity is formingin the extra-embryonic mesoderm, compressing the yolk sac

Front 10

Name the mesenchymal layer that develops around the primary yolk sac and amnionic cavity.

Back 10

extra-embryonic mesoderm splits into two layers the extra-embryonic somatic mesoderm lines the amnion and the trophoblast, while the extra-embryonic splanchnic mesoderm lines the yolk sac

Front 11

True are false: Does the extra-embryonic mesoderm eventually surrounds the cytotrophoblasts.

Back 11

False- However the extra-embryonic somatic mesoderm and the two layers of trophoblast fuse to become the chorion which surounds the entire embryo and amniotic cavity

Front 12

Spaces form within the syncytiotrophoblast that become filled with a mixture of maternal blood from ruptured capillaries and endometrial secretions, a nutritive fluid for developing embryo. What are these spaces called?

Back 12

lacunae- these spaces represent the beginning of palacental circulatory system development. The lacunae fuse and for the primordium for the intervillus space in the placenta.

Front 13

primary chorionic villi

Back 13

the fingerlike projections of cytotrophoblasts that represent the first stage of development of the placenta that develop at the end of week 2.

Front 14

Describe the structure(s) generated by the formation, expansion and fusion of spaces within the extraembryonic mesoderm.

Back 14

Intraembryonic celom

Front 15

Which extraembryonic mesoderm lines the trophoblast and amnion?

Back 15

extra-embryonic somatic mesoderm

Front 16

Which extraembryonic mesoderm lines the yolk sac?

Back 16

extra-embryonic splanchnic mesoderm

Front 17

What is the Chorion?

Back 17

the chorion is the combination the two layers of the trophoblast and the extra-embryonic somatic mesoderm

Front 18

What important embryonic structure will develop at the site of the prechordal plate?

Back 18

the prechordal plate is the future site of the mouth this becomes the orophyrangal membrane in the trilaminar embryo