Biology: Sperm and Oocyte Fertilization

Questions and Answers

What is the first stage that spermatozoa must undergo to acquire the ability to fertilize an oocyte?

Capacitation (correct)

Fertilization

Cervical traversal

Acrosome reaction

How many sperm cells are typically considered active and normal per ejaculation, out of the total produced?

5 million

1 million

200 million

500 (correct)

After fertilization, where does the fertilized egg travel before implantation?

To the uterus (correct)

To the ampulla

To the cervix

To the ovaries

What volume of semen is typically produced during an ejaculation?

2-6 ml Signup and view all the answers

How long does it typically take for semen to liquefy after ejaculation?

30 minutes Signup and view all the answers

Which of the following processes occurs before spermatozoa can fertilize an oocyte?

Capacitation Signup and view all the answers

What percentage of sperm cells produced during ejaculation are considered fertile?

0.2-0.3% Signup and view all the answers

Which of the following statements is true regarding spermatozoa and their ability to fertilize oocytes?

Spermatozoa achieve fertilization capability through capacitation and the acrosome reaction. Signup and view all the answers

What marks the beginning of the menstrual cycle?

First day of bleeding Signup and view all the answers

Which hormone is produced by the anterior pituitary gland during a menstrual cycle?

Follicle-stimulating hormone (FSH) Signup and view all the answers

Which hormonal component is not part of the regulation of the menstrual cycle?

Oxytocin Signup and view all the answers

During which phase of the menstrual cycle does the body prepare for a potential pregnancy?

Luteal phase Signup and view all the answers

What is the typical range of blood lost during menstruation?

25-35 mL Signup and view all the answers

What is formed by the hypoblast in relation to the cytotrophoblast?

A thin membrane lining the cytotrophoblast Signup and view all the answers

Which characteristic of the syncytiotrophoblast is first observed on the 9th day?

Formation of vacuoles Signup and view all the answers

What major change occurs in the maternal blood vessels during the establishment of the uteroplacental circulation?

They become congested and dilated Signup and view all the answers

What happens to the capillaries during implantation bleeding around the 27-28th day of fertilization?

Blood from maternal capillaries reaches lacunar spaces Signup and view all the answers

The bilaminar germ disc is composed of which two layers?

Hypoblast and epiblast Signup and view all the answers

During which stage of embryonic development is the trophoblast characterized by a distinct villous structure?

After the 8th day of implantation Signup and view all the answers

What is the primary role of the cytotrophoblast in early embryonic development?

Invades maternal tissues for implantation Signup and view all the answers

What term is used to describe the intercommunicating network formed by the lacunar spaces in the trophoblast?

Sinusoidal structure Signup and view all the answers

What cells adjacent to the cytotrophoblast are specifically referred to as amnioblasts?

Epiblast cells Signup and view all the answers

During which stage do vacuoles appear in the syncytium, leading to the formation of lacunae?

Lacunar stage Signup and view all the answers

What primarily closes the original surface defect during the 9th day of development?

Fibrin coagulum Signup and view all the answers

What does the bilaminar disc consist of during the 9th day of development?

Layer of cuboidal endodermal cells and columnar epiblast cells Signup and view all the answers

What significant development occurs at the embryonic pole of the trophoblast by the 11th and 12th days?

Formation of large lacunae Signup and view all the answers

Which cells are responsible for creating the exocoelomic membrane?

Flattened cells Signup and view all the answers

What happens to the blastocyst by the end of the 12th day of development?

It becomes completely embedded in the endometrial stroma. Signup and view all the answers

What is indicated by the presence of lacunae in the syncytiotrophoblast?

Development of maternal circulation Signup and view all the answers

What is the role of the corpus luteum during pregnancy?

It produces hormones to support the early pregnancy. Signup and view all the answers

What happens if no fertilization occurs during the 28-day cycle?

The endometrium degenerates and transforms into the corpus albicans. Signup and view all the answers

What is mittelschmerz?

Slight pain experienced during ovulation. Signup and view all the answers

Which medication is commonly prescribed to stimulate ovulation?

Clomiphene citrate Signup and view all the answers

During early pregnancy, what could slight pain in the hypogastric area indicate?

Appendicitis or uterine infection. Signup and view all the answers

What is the fate of the blastocyst after fertilization?

It begins to implant into the functional layer of the endometrium. Signup and view all the answers

What condition might a doctor rule out when a woman presents with hypogastric pain?

Appendicitis Signup and view all the answers

Which of the following best describes the role of the zona pellucida in fertilization?

It traps the blastocyst until implantation occurs. Signup and view all the answers

Study Notes

Fertilization Process

Spermatozoa must undergo capacitation and the acrosome reaction before fertilizing the oocyte.
Just arriving at the ampulla does not grant sperm the ability to fertilize; maturation steps are required.
Capacitation prepares sperm for ovum penetration; only then are they capable of fertilization.

Sperm Characteristics

Normal ejaculation results in 200-300 million sperm, but only around 500 are active and fertile.
Seminal fluid volume during ejaculation ranges from 2-6 mL.
Sperm undergo liquefaction within approximately 30 minutes post-ejaculation.

Embryo Development

Upon fertilization, the fertilized egg (blastocyst) travels to the fallopian tube and reaches the uterus for implantation.
The blastocyst embeds deeply within the endometrium, which supports early pregnancy.
If fertilization does not occur, the endometrium and the corpus luteum degenerate, forming a corpus albicans.

Clinical Significance of Ovulation

Hypogastric pain in women may indicate conditions like appendicitis or uterine infections, especially in early pregnancy.
History of menstruation can help physicians rule out potential issues during consultations related to conception difficulties.
Evaluation of the ovulation cycle is crucial; medication may be administered to induce ovulation if absent.

Clomiphene Citrate

Clomiphene citrate (Clomid) can stimulate ovulation by activating the anterior pituitary hormone.

Early Embryo Development

The bilaminar disc consists of epiblast (columnar) and hypoblast (cuboidal) layers.
The blastocyst shows significant embedding by the 9th day, protected by a fibrin coagulum over the original surface defect.

Trophoblast Development

The lacunar stage begins around the 11th and 12th day, where large vacuoles form within the syncytium, contributing to maternal-fetal circulation.
The syncytiotrophoblast facilitates the formation of maternal blood spaces, known as sinusoids, at the embryonic pole.

Menstrual Cycle

The average menstrual cycle is approximately 28 days with a normal range of 25-35 days.
Day 1 of the cycle coincides with the onset of menstruation, marking the beginning of the follicular phase.
The typical blood loss during menstruation is around 30 mL.

Hormonal Regulation

The menstrual cycle is regulated by hormones such as estrogen, progesterone, LH, and FSH.
It consists of two main phases: follicular (proliferative) phase and luteal (secretory) phase.

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Description

This quiz explores the processes of capacitation and acrosome reaction that spermatozoa undergo before they can fertilize an oocyte. Understand the important physiological changes that allow for successful fertilization in the female reproductive tract.