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?

<p>The placenta is completely covering the internal os. (C)</p> Signup and view all the answers

What is the most common type of ectopic pregnancy?

<p>Tubal ectopic pregnancy. (A)</p> Signup and view all the answers

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

<p>Progesterone (C)</p> Signup and view all the answers

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

<p>Decidua basalis (B)</p> Signup and view all the answers

What is the fate of the decidua capsularis during pregnancy?

<p>It fuses and degenerates. (B)</p> Signup and view all the answers

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

<p>Bilaminar disc (D)</p> Signup and view all the answers

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

<p>Amniotic cavity (C), Primary yolk sac (D)</p> Signup and view all the answers

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

<p>Syncytiotrophoblast (D)</p> Signup and view all the answers

What structure is formed between the epiblast and amnioblast?

<p>Amniotic cavity (A)</p> Signup and view all the answers

Which combination of layers form the chorion?

<p>Syncytiotrophoblast, cytotrophoblast, and somatic extra-embryonic mesoderm (C)</p> Signup and view all the answers

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

<p>Secretion of enzymes by the trophoblast (B)</p> Signup and view all the answers

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

<p>Placenta previa centralis (D)</p> Signup and view all the answers

What is a potential complication of a tubal ectopic pregnancy?

<p>Severe bleeding from the ruptured fallopian tube (C)</p> Signup and view all the answers

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

<p>Upper part of the posterior uterine wall (D)</p> Signup and view all the answers

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

<p>Digesting and remodeling maternal endometrial tissue (C)</p> Signup and view all the answers

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

<p>Progesterone (C)</p> Signup and view all the answers

What structural change occurs to the decidua parietalis during pregnancy?

<p>It fuses and degenerates (C)</p> Signup and view all the answers

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

<p>Epiblast (B)</p> Signup and view all the answers

What significant function does the syncytiotrophoblast perform during implantation?

<p>Produces HCG to maintain the corpus luteum (B)</p> Signup and view all the answers

What is formed by the somatic mesoderm during early development?

<p>The chorion (C)</p> Signup and view all the answers

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

<p>It forms maternal part of the placenta (A)</p> Signup and view all the answers

What structures are encompassed by the term 'chorion'?

<p>Syncytiotrophoblast, cytotrophoblast, and somatic mesoderm (A)</p> Signup and view all the answers

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

<p>Syncytiotrophoblast (B)</p> Signup and view all the answers

Flashcards

Implantation Definition

Blastocyst embedding in the endometrium

Implantation Site

Upper part of posterior uterine wall, near fundus

Placenta Previa

Implantation in the lower uterine segment.

Ectopic Pregnancy

Implantation outside uterine cavity

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Tubal Ectopic

Common ectopic pregnancy type in fallopian tubes

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Decidua

The endometrium of a pregnant uterus, structured like the secretory phase endometrium, under hormonal control of progesterone.

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Decidua capsularis

Part of the endometrium covering the fetus; it fuses and degenerates.

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Decidua parietalis

Part of the endometrium lining the uterine cavity; it fuses and degenerates.

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Decidua basalis

Part of the endometrium between the fetus and myometrium; forms the maternal part of the placenta.

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Syncytiotrophoblast

Outer layer of the trophoblast; produces enzymes to erode the endometrium and secretes HCG to maintain corpus luteum.

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Cytotrophoblast

Inner layer of the trophoblast.

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Chorionic vesicle formation

Trophoblast differentiation into syncytiotrophoblast and cytotrophoblast, laying the basis for the chorion. Inner cell mass forms a bilaminar disc of epiblast (upper) and hypoblast (lower).

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Extra-embryonic mesoderm

Forms from the blastocyst and divides into somatic and splanchnic mesoderm; these layers surround the amniotic cavity and yolk sac, respectively.

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Implantation Definition

Blastocyst embedding in the uterine lining (endometrium)

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Implantation Site

Usually the upper part of the posterior uterine wall near the fundus.

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Placenta Previa Anomalies

Abnormal implantation of the placenta in the lower uterine segment.

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Ectopic Pregnancy Definition

Implantation outside of the uterus.

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Common Ectopic Pregnancy Type

Tubal ectopic pregnancy is the most common type.

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Decidua

Endometrium of the pregnant uterus, similar to secretory phase endometrium; under progesterone control.

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Decidua basalis

Part of the endometrium between the fetus and myometrium, forming maternal placenta part.

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Syncytiotrophoblast

Outer trophoblast layer; erodes endometrium & produces HCG to maintain corpus luteum.

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Chorionic vesicle formation

Trophoblast differentiation into two layers, prepping for chorion formation.

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Extra-embryonic mesoderm

Layer that divides into somatic and splanchnic mesoderm, connecting embryo's support structures.

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Bilaminar disc

Inner cell mass layer; composed of epiblast & hypoblast.

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Amniotic cavity

Fluid-filled space between epiblast and amnioblast; embryo's fluid protective environment, critical for development.

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HCG

Hormone produced by syncytiotrophoblast; keeps corpus luteum active.

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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

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