Embryology Week 2 Quiz

Questions and Answers

What are the two layers of the trophoblast during Day 8 of development?

Cytotrophoblast and syncytiotrophoblast (correct)

Hypoblast and epiblast

Mononucleated cells and bilaminar disc

Inner cell mass and outer cell mass

Which structure is adjacent to the amniotic cavity during the second week of development?

Trophoblast

Hypoblast

Syncytiotrophoblast

Epiblast (correct)

What happens to the embryoblast at the beginning of the second week?

It becomes fully developed.

It forms a trilaminar disc.

It embeds deeper in the endometrial stroma.

It differentiates into two layers. (correct)

What structure is formed by the coupling of the hypoblast and epiblast?

Bilaminar disc Signup and view all the answers

What is true about the amnioblast during the second week of development?

It is formed by the cytotrophoblast. Signup and view all the answers

On which day does the blastocyst become partially embedded in the endometrial stroma?

Day 8 Signup and view all the answers

Which layer of the trophoblast has distinct cell boundaries?

Cytotrophoblast Signup and view all the answers

What structure appears as a small cleft during the second week of development?

Amniotic cavity Signup and view all the answers

What occurs after the sperm penetrates the zona pellucida?

No further sperm can penetrate once the zona pellucida is breached. Signup and view all the answers

What is restored to the diploid number during fertilization?

The total genetic material from both male and female. Signup and view all the answers

What is formed immediately after the sperm penetrates the oocyte membrane?

Secondary meiotic division. Signup and view all the answers

How does the determination of sexual characteristics occur during fertilization?

From the combination of male XY and female XX chromosomes. Signup and view all the answers

Which stage follows the determination of sexuality and restoration of the diploid number?

Formation of zygote. Signup and view all the answers

What role do proteins and enzymes released by the zona pellucida play?

They assist the sperm in penetrating the zona pellucida. Signup and view all the answers

What differentiates in the oocyte after sperm penetration?

Both the head and the tail of the sperm. Signup and view all the answers

What is a key characteristic of the zona pellucida during fertilization?

It becomes impermeable to sperm after one has penetrated. Signup and view all the answers

What is the primary function of fimbriae in the reproductive system?

To collect oocytes and direct them to the uterine tube Signup and view all the answers

At what stage of development is the blastomere formed?

After fertilization when the zygote divides into two cells Signup and view all the answers

What happens to the zona pellucida during early embryonic development?

It disappears by the end of the fourth day after fertilization Signup and view all the answers

What role does human chorionic gonadotropin (Hcg) play during early embryonic development?

It maintains the corpus luteum and progesterone production Signup and view all the answers

At approximately how many hours post-fertilization does the four-cell stage occur?

40 hours Signup and view all the answers

Which hormone is primarily responsible for preparing the endometrium for implantation?

Progesterone Signup and view all the answers

What signifies the transition from the morula stage to the blastocyst stage?

The entrance of fluids into the embryo Signup and view all the answers

What is the significance of the inner cell mass in embryonic development?

It forms the future embryoblast and embryo Signup and view all the answers

What occurs to the corpus luteum if fertilization does not take place?

It degenerates and causes menstruation. Signup and view all the answers

At what stage does the human blastocyst begin to penetrate the uterine mucosa?

By the sixth day of development. Signup and view all the answers

Which layer of the endometrium has its own blood vessels and will degenerate if pregnancy does not occur?

Basal layer. Signup and view all the answers

What are the components of the blastocyst represented in the content?

Outer cell mass, inner cell mass, and trophoblast. Signup and view all the answers

If conception occurs, what changes happen to the corpus luteum?

It continues to produce hormones like progesterone. Signup and view all the answers

What happens to the compact and spongy layers of the endometrium during the secretory phase?

They thicken and prepare for implantation. Signup and view all the answers

What structure will become the future placenta during early development?

Trophoblast Signup and view all the answers

What is one of the first noticeable changes in the second week of development?

Implantation into the uterine wall. Signup and view all the answers

What hormone is primarily responsible for triggering ovulation?

LH Signup and view all the answers

Which substance levels remain high if fertilization occurs?

Progesterone and human chorionic hormone (hCG). Signup and view all the answers

Which phase of the menstrual cycle is characterized by high levels of FSH and the growth of ovarian follicles?

Follicular phase Signup and view all the answers

What happens if a female is not ovulating based on LH levels?

LH levels will be low Signup and view all the answers

When does progesterone begin to rise in the menstrual cycle?

During the luteal phase Signup and view all the answers

What is the primary role of Clomiphene in female fertility treatment?

Stimulates ovarian egg growth Signup and view all the answers

Which day of the menstrual cycle is typically associated with ovulation?

Day 14 Signup and view all the answers

What is the main function of the endometrial cycle?

To prepare the uterine lining for potential implantation Signup and view all the answers

Study Notes

2nd Week of Development

On Day 8, the blastocyst is partially embedded in the endometrial stroma.
Trophoblast differentiates into two layers: cytotrophoblast (inner) and syncytiotrophoblast (outer).
The embryoblast of the inner cell mass develops into two layers: hypoblast (adjacent to blastocyst) and epiblast (adjacent to amniotic cavity).
The combination of epiblast and hypoblast forms the bilaminar disc and marks the beginning of the amniotic cavity.
Events on Day 9 include the penetration of the corona radiata and subsequent penetration of the zona pellucida by sperm, leading to fertilization.
After fertilization, secondary meiotic division occurs within the oocyte, resulting in male and female protocytes.
Fertilization restores the diploid number of chromosomes (46) and determines genetic sex (XY for males, XX for females).
Cleavage begins with the formation of two cells, progressing to four, then 16 (blastomeres), eventually forming a morula within the zona pellucida.
The morula transforms into a blastocyst, comprised of an inner cell mass (future embryoblast) and an outer layer (trophoblast, future placenta).
The blastocyst begins to embed into the endometrium, indicating the transition from the first to the second week of development.
Human chorionic gonadotropin (hCG) is produced by the developing blastocyst to maintain progesterone production from the corpus luteum, crucial for implantation preparation.
The menstrual cycle includes three phases: follicular phase, luteal phase, and menstrual phase; each regulated by various hormones including FSH, LH, and estrogen.
During the follicular phase, FSH stimulates follicle growth and endometrial preparation, leading to ovulation on Day 14, marked by a spike in LH.
If pregnancy does not occur, the corpus luteum degenerates, triggering menstrual cycle initiation by affecting the endometrial layers.
Conception may influence future menstrual cycles, maintaining high progesterone and hCG levels to support the pregnancy.

Test Yourself Questions

What is noticeable in the 2nd week of development?
What two cavities are formed from mesoderm?

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Description

Test your knowledge about the 2nd week of embryonic development with this quiz. Covering key events from Day 8 to Day 13, it assesses your understanding of blastocyst implantation and trophoblast differentiation. Perfect for students of developmental biology or embryology.