أسئلة الخامسة امبريولوجي (قبل التعديل)

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Questions and Answers

What primarily happens during the process of implantation?

The trophoblast becomes fragmented.

The embryo forms multiple layers of cells.

The zona pellucida strengthens the embryo.

The blastocyst embeds into the endometrium. (correct)

Where does implantation typically occur within the uterus?

Midline of the uterine cavity.

Upper part of the posterior uterine wall near the fundus. (correct)

Lower part of the anterior uterine wall.

Near the cervical canal.

Which power of the trophoblast helps in implanting the blastocyst into the endometrium?

Analytical power.

Adhesive power. (correct)

Histolytic power.

Regenerative power.

What defines placenta previa centralis?

The placenta is completely covering the internal os. Signup and view all the answers

What is the most common type of ectopic pregnancy?

Tubal ectopic pregnancy. Signup and view all the answers

What is the primary hormone influencing the structure of the decidua during pregnancy?

Progesterone Signup and view all the answers

Which part of the decidua forms the maternal aspect of the placenta?

Decidua basalis Signup and view all the answers

What is the fate of the decidua capsularis during pregnancy?

It fuses and degenerates. Signup and view all the answers

The inner cell mass of the blastocyst differentiates into what structure?

Bilaminar disc Signup and view all the answers

What do the somatic and splanchnic mesoderms surround in the blastocyst formation?

Amniotic cavity Signup and view all the answers

What type of trophoblast layer produces human chorionic gonadotropin (HCG)?

Syncytiotrophoblast Signup and view all the answers

What structure is formed between the epiblast and amnioblast?

Amniotic cavity Signup and view all the answers

Which combination of layers form the chorion?

Syncytiotrophoblast, cytotrophoblast, and somatic extra-embryonic mesoderm Signup and view all the answers

What primarily causes the loss of the zona pellucida during implantation?

Secretion of enzymes by the trophoblast Signup and view all the answers

Which form of placenta previa involves the placenta completely covering the internal os?

Placenta previa centralis Signup and view all the answers

What is a potential complication of a tubal ectopic pregnancy?

Severe bleeding from the ruptured fallopian tube Signup and view all the answers

In which anatomical location does implantation of the blastocyst typically occur?

Upper part of the posterior uterine wall Signup and view all the answers

What is the histolytic power of the trophoblast responsible for during implantation?

Digesting and remodeling maternal endometrial tissue Signup and view all the answers

What is the primary hormonal influence on the decidua during pregnancy?

Progesterone Signup and view all the answers

What structural change occurs to the decidua parietalis during pregnancy?

It fuses and degenerates Signup and view all the answers

Which part of the inner cell mass gives rise to the upper columnar layer?

Epiblast Signup and view all the answers

What significant function does the syncytiotrophoblast perform during implantation?

Produces HCG to maintain the corpus luteum Signup and view all the answers

What is formed by the somatic mesoderm during early development?

The chorion Signup and view all the answers

Which of the following describes the fate of the decidua basalis?

It forms maternal part of the placenta Signup and view all the answers

What structures are encompassed by the term 'chorion'?

Syncytiotrophoblast, cytotrophoblast, and somatic mesoderm Signup and view all the answers

Which layer of the trophoblast is responsible for eroding the endometrium?

Syncytiotrophoblast Signup and view all the answers

Study Notes

Second Week Implantation

Definition: Embedding the blastocyst into the endometrium
Site: Upper posterior uterine wall, near the fundus
Time: Begins at the end of the first week and continues until the end of the second week
Mechanism:
- Loss of zona pellucida exposes the trophoblast
- Exposed trophoblast has two abilities:
  - Adhesive power: Attaches to the endometrium
  - Histolytic power (enzymatic): Enables the blastocyst to digest the endometrium
  - Fibrin plug fills the digested area

Anomalies of Implantation

Placenta Previa: Implantation of the blastocyst into the lower uterine segment
- Lateralis: Placenta is away from the internal os
- Marginalis: Placenta partially covers the internal os
- Centrals: Placenta completely covers the internal os
Ectopic Pregnancy: Implantation of the blastocyst outside the uterine cavity
- Tubal (most common): Caused by early loss of zona pellucida or delayed transport of zygote
- Ovarian: Primary is implantation into the ovary; secondary is rupture of a tubal pregnancy
- Peritoneal (abdominal): Primarily in the recto-uterine pouch

Decidua

Definition: Endometrium of a pregnant uterus
Structure: Similar to the endometrium in the secretory phase
Hormonal control: Under the influence of progesterone
Parts:
- Decidua capsularis: Part of the endometrium covering the fetus; Fuses and degenerates
- Decidua parietalis: Part of the endometrium lining the uterine cavity; Fuses and degenerates
- Decidua basalis: Part of the endometrium between the fetus and myometrium; Forms the maternal part of the placenta

Blastocyst Changes ("Chorionic Vesicle Formation")

Trophoblast: Outer layer of trophoblast
- Syncytiotrophoblast: Produces proteolytic enzymes to erode the endometrium; secretes human chorionic gonadotropin (hCG) to maintain corpus luteum and progesterone production for 4 months.
- Cytotrophoblast: Inner layer of trophoblast
Inner cell mass: Becomes a bilaminar disc
- Epiblast: Upper layer
- Hypoblast: Lower layer
Blastocele: Becomes the amniotic cavity between epiblast and amnioblast, and primary yolk sac between hypoblast and Hausser membrane
Extraembryonic mesoderm: Divides & forms somatic and splanchnic mesoderm. Somatic lines cytotrophoblast, splanchnic covers yolk sac. They remain in contact, forming the connecting stalk (umbilical cord).
Chorion: Formed by syncytiotrophoblast, cytotrophoblast and somatic extraembryonic mesoderm