أسئلة المحاضرة الرابعة امبريولوجي (قبل التعديل)
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Questions and Answers

What process occurs when two or more ova are fertilized by sperm from separate acts of coitus during the same menstrual cycle?

  • Cleavage
  • Zygotic division
  • Gestation
  • Superfecundation (correct)

What is the main characteristic of the cleavage stage in embryonic development?

  • Formation of organs
  • Formation of the umbilical cord
  • Development of the placenta
  • Repeated mitosis of blastomers (correct)

At what stage is the morula formed, and how many cells does it typically consist of?

  • 16-32 cells, formed 3 days after fertilization (correct)
  • 8-16 cells, formed 2 days after fertilization
  • 4-8 cells, formed 4 days after fertilization
  • 32-64 cells, formed 1 week after fertilization

Which component of the blastocyst develops into the fetal part of the placenta?

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

How many days after fertilization does the blastocyst stage occur?

<p>4 days (C)</p> Signup and view all the answers

What is capacitation in the fertilization process?

<p>The removal of seminal plasma proteins from sperm (A)</p> Signup and view all the answers

Where does fertilization typically occur?

<p>In the ampulla of the uterine tube (B)</p> Signup and view all the answers

Which substance is released during the acrosomal reaction to aid in penetrating the zona pellucida?

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

What is the role of the zona cortical reaction?

<p>To make the zona pellucida impermeable to additional sperm (D)</p> Signup and view all the answers

What determines the sex of the embryo during fertilization?

<p>Whether the sperm carries an X or Y chromosome (C)</p> Signup and view all the answers

What happens immediately after the fertilization process completes?

<p>The initiation of zygote cell division (A)</p> Signup and view all the answers

Which of the following is an anomaly related to fertilization?

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

What is the outcome of dispermy during fertilization?

<p>Triploidy zygote (A)</p> Signup and view all the answers

What is the correct sequence of cell division stages during cleavage after fertilization?

<p>2 cell stage, 4 cell stage, 8 cell stage (A)</p> Signup and view all the answers

Which of the following correctly describes the morula stage of embryonic development?

<p>It consists of 16-32 cells and is formed 3 days after fertilization. (C)</p> Signup and view all the answers

What structures are included in the blastocyst stage?

<p>Trophoblast, blastocele, and inner cell mass (A)</p> Signup and view all the answers

How many days after fertilization does the formation of the blastocyst occur?

<p>4 days (D)</p> Signup and view all the answers

Which of the following statements about the trophoblast is true?

<p>It consists of outer flat cells and contributes to the placenta. (C)</p> Signup and view all the answers

What is the primary aim of capacitation during fertilization?

<p>To enhance the motility of the sperm (D)</p> Signup and view all the answers

Which enzyme released during the acrosomal reaction is responsible for aiding sperm in penetrating the corona radiata?

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

What is the significance of the zona cortical reaction following fertilization?

<p>It prevents further sperm from fertilizing the oocyte (B)</p> Signup and view all the answers

At which point in fertilization does the male pro-nucleus formation occur?

<p>Once the sperm's tail is lost and nucleus enlarges (D)</p> Signup and view all the answers

How many chromosomes are present in the zygote formed after the fusion of male and female pro-nuclei?

<p>46 chromosomes (B)</p> Signup and view all the answers

Which of the following describes parthenogenesis?

<p>An embryo developing without fertilization (A)</p> Signup and view all the answers

Which is the correct sequence of events leading to the formation of a zygote?

<p>Capacitation, acrosomal reaction, fusion, meiosis (C)</p> Signup and view all the answers

What happens to the female gamete during fertilization after the second meiosis resumes?

<p>It results in the formation of a female pro-nucleus (B)</p> Signup and view all the answers

In which stage of early embryonic development is the blastocyst formed?

<p>4th day after fertilization (B)</p> Signup and view all the answers

What is the primary characteristic of the morula stage in embryonic development?

<p>It consists of 16 to 32 cells. (B)</p> Signup and view all the answers

Which component of the blastocyst develops into the embryo?

<p>Inner cell mass (embryoblast) (A)</p> Signup and view all the answers

What is the process of repeated mitosis of the zygote called?

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

What forms the fetal part of the placenta during the blastocyst stage?

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

What is the primary role of hyaluronidase during fertilization?

<p>To penetrate the corona radiata (A)</p> Signup and view all the answers

Which statement accurately describes the process of capacitation?

<p>It involves the removal of seminal plasma proteins from the sperm's head. (A)</p> Signup and view all the answers

Which of the following best describes the outcome of the zona cortical reaction?

<p>It makes the zona pellucida impermeable to additional sperm. (A)</p> Signup and view all the answers

What is the significance of the site known as the ampulla in fertilization?

<p>It is the ideal location for the fertilization of the ovum. (A)</p> Signup and view all the answers

What happens during the acrosomal reaction?

<p>Enzymes are released to facilitate penetration of the zona pellucida. (C)</p> Signup and view all the answers

Which chromosome configuration occurs when a sperm carrying an X chromosome fertilizes an ovum?

<p>XX leading to a female embryo (B)</p> Signup and view all the answers

What process results in triploidy during fertilization?

<p>Dispermy, with two sperms penetrating one ovum (A)</p> Signup and view all the answers

What is the key outcome of the fusion of the male and female pro-nuclei?

<p>Formation of the embryo with 46 chromosomes (D)</p> Signup and view all the answers

Flashcards

Fertilization Definition

The fusion of male and female gametes (sperm and egg)

Fertilization Site

The ampulla of the uterine tube

Capacitation

Activation of sperm in the female reproductive tract to increase its ability to fertilize the ovum

Acrosomal Reaction

Release of enzymes from the sperm's acrosome to penetrate the egg's layers.

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Zona Reaction

Making the ovum's outer layer impenetrable to other sperm.

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Sex Determination

The sperm's chromosome (X or Y) determines the embryo's sex

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Embryo Health Check

Fertilization process can determine early viability of embryo

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Parthenogenesis

Development of an embryo without fertilization (all female offspring)

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Superfecundation

Fertilization of two or more eggs in the same menstrual cycle from separate acts of intercourse.

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Cleavage

Repeated cell division of a zygote, increasing cell number while traveling in the fallopian tube.

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Morula

16-32 cell stage of the early embryo, enclosed within the zona pellucida, entering the uterus.

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Blastocyst Stage

Embryo stage 4 days after fertilization, with a fluid-filled cavity (blastocele), outer layer (trophoblast), and inner cell mass (embryoblast).

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Blastomeres

Cells created during cleavage of the zygote.

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Superfecundation definition

Fertilization of two or more ova in the same menstrual cycle from separate acts of intercourse.

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Cleavage stages

Repeated cell division of the zygote, increasing cell number in the fallopian tube.

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Morula description

A 16-32 cell structure, within the zona pellucida, entering the uterus.

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Blastocyst characteristics

Embryo stage 4 days after fertilization, with a cavity (blastocele), outer layer (trophoblast), and inner cell mass (embryoblast).

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Blastomere definition

Individual cells created during early cell division of the zygote.

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Fertilization Definition

Union of male and female gametes (sperm and egg).

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Fertilization Site (location)

Ampulla of the uterine tube.

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Capacitation of Sperms

Sperm activation for fertilization.

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Acrosomal Reaction Function

Enzyme release to pierce the ovum's protective layers.

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Zona Reaction Purpose

Preventing multiple sperm entry into the ovum.

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Sex Determination via Sperm

Sperm's chromosome (X or Y) determines embryo sex.

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Parthenogenesis Description

Embryo development without fertilization (all female).

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Dispermy/Triploidy Result

Two sperm fertilize one ovum, forming a triploid zygote.

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Fertilization Definition

The union of male and female gametes (sperm & egg).

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Fertilization Site

Ampulla of uterine tube

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Capacitation - Definition

Sperm activation for fertilization in female tract

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Acrosomal Reaction - What it does

Sperm releases enzymes to penetrate the egg.

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Zona Reaction - Purpose

Preventing multiple sperm entry into egg

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Sex Determination - How

Sperm's chromosome (X or Y) sets embryo sex.

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Parthenogenesis - What it is

Embryo develops without fertilization; all female.

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Dispermy/Triploidy - Result

Two sperm fertilize one egg - forming a triploid zygote

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Superfecundation

Fertilization of two or more eggs in the same menstrual cycle from separate acts of intercourse.

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Cleavage

Rapid cell division (mitosis) of a fertilized egg (zygote) in the fallopian tube.

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Morula

16-32 cell stage of the embryo, enclosed in the zona pellucida, entering the uterus.

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Blastocyst

Embryo stage 4 days after fertilization, with a fluid-filled cavity (blastocele), outer layer (trophoblast), and inner cell mass (embryoblast).

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Blastomere

Individual cells produced during cleavage of a fertilized egg.

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Study Notes

Fertilization

  • Definition: Meeting and union of male and female gametes
  • Site: Ampulla of uterine tube
  • Steps:
    • Sperm deposited in posterior fornix of vagina (200-600 x 10⁶ sperms)
    • Capacitation: Removal of seminal plasma proteins from sperm head, making sperm more active for fertilization
    • Acrosomal reaction: Enzymes released from sperm's acrosome, penetrating the corona radiata and zona pellucida
    • Fusion of sperm and egg membranes
    • Zona cortical reaction: Zona pellucida becomes impermeable to other sperm, preventing polyspermy
    • Second meiosis of the ovum
    • Formation of male and female pronuclei
    • Union of pronuclei: Forming the zygote

Results of Fertilization

  • Sex determination: Y chromosome = male, X chromosome = female
  • Embryonic health: Assessment of embryo's health
  • Restoration of diploid number: Restores normal 46 chromosomes
  • Initiation of cell division: Begins zygote cell division

Anomalies

  • Parthenogenesis: Pregnancy without fertilization (all offspring female)
  • Dispermy triploidy: Two sperm fertilize one egg, resulting in a triploid zygote
  • Superfecundation: Fertilization of more than one egg released during the same menstrual cycle

Cleavage (Segmentation)

  • Definition: Repeated mitosis of blastomeres, increasing cell number rapidly
  • Steps:
    • 2, 4, 8 cell stage
    • Blastomeres undergo mitosis as zygote travels through uterine tube
    • Morula formation: 16-32 cells within zona pellucida (3 days post fertilization), enters uterine cavity
    • Blastocyst formation: 4th day after fertilization
      • Blastocele: Fluid-filled cavity inside the blastocyst
      • Trophoblast: Outer layer of cells, forms fetal part of placenta
      • Inner cell mass (embryoblast): Mass of cells that forms the embryo

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