Gamete Physiology: Sperm Capacitation and Fertilization

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Questions and Answers

During what period after conception does the embryonic disk differentiate into 3 primary germ layers?

1 week

8 weeks

3 weeks (correct)

15 weeks

Which primary germ layer develops into the bones and teeth?

Ectoderm

Mesoderm (correct)

Endoderm

All of the above

What is the approximate length of the embryo at the end of the embryonic stage?

3 cm (correct)

10 cm

5 cm

1 cm

Why are developing areas with rapid cell division more vulnerable to malformation?

Due to environmental teratogens Signup and view all the answers

At the end of the embryonic stage, which of the following is true?

All organ systems and external structures are present Signup and view all the answers

What is the primary function of the trophoblast in the blastocyst?

To facilitate implantation in the uterine wall Signup and view all the answers

During what stage of development does the fluid-filled cavity appear?

Blastocyst Signup and view all the answers

What is the result of the trophoblast's secretion of protease and protein digestive enzymes?

The degeneration of the zona pellucida Signup and view all the answers

Where does the trophoblast typically attach itself to the uterus?

The anterior or posterior fundal region Signup and view all the answers

How many days after conception does implantation typically occur?

6-10 days Signup and view all the answers

What is the term for the process by which the blastocyst binds to and buries within the uterine wall?

Implantation Signup and view all the answers

What is the primary function of hyaluronidase enzymes during fertilization?

To aid in the capacitation process of the sperm Signup and view all the answers

Where does fertilization typically take place in the female reproductive tract?

In the ampulla of the uterine tube Signup and view all the answers

What is the result of the fusion of sperm and ovum nuclei during fertilization?

The formation of a diploid zygote Signup and view all the answers

What is the term for the process of mitotic cellular replication that occurs after fertilization?

Cleavage Signup and view all the answers

What is the structure that surrounds the morula, a solid ball of 16 cells?

Zona pellucida Signup and view all the answers

How often do cell divisions occur during the cleavage stage of fertilization?

Every 12 hours Signup and view all the answers

What is the primary component of the amniotic fluid volume?

Urine excreted by the fetus Signup and view all the answers

At what week does the fetus's Central nervous system begin to develop from the ectoderm?

5th week Signup and view all the answers

When do the kidneys of the fetus begin to function?

4 weeks after kidney formation Signup and view all the answers

What is the main function of the gastrointestinal system in the fetus near term?

Forming meconium from swallowed amniotic fluid Signup and view all the answers

What is the approximate size of the fetal brain at term compared to an adult brain?

One fourth the size Signup and view all the answers

When do the distinguishing characteristics of sex differentiation appear in the embryo?

9th week Signup and view all the answers

What is the purpose of the vernix caseosa in the fetal development?

To protect the skin of the fetus from the amniotic fluid Signup and view all the answers

At what week of gestation does the fetus produce IgM immunoglobulins?

By the end of the first trimester Signup and view all the answers

What is the role of fontanels in the fetal development?

To allow the bones of the skull to mold during birth Signup and view all the answers

What is the significance of IgG immunoglobulins in the fetal development?

It provides passive immunity to the fetus Signup and view all the answers

When do the toenails develop in the fetal development?

18 weeks Signup and view all the answers

What is the significance of lanugo hair in the fetal development?

It appears first on the eyebrows and upper limbs at 12 weeks Signup and view all the answers

Study Notes

Germ Layer Differentiation and Development

The embryonic disk differentiates into three primary germ layers during the third week after conception.
The mesoderm germ layer develops into bones and teeth.
At the end of the embryonic stage, the embryo measures approximately 3 centimeters in length.

Vulnerability During Development

Areas with rapid cell division are more prone to malformations due to increased sensitivity to environmental factors and genetic influences.

Embryonic Stage Overview

At the end of the embryonic stage, several critical structures and systems are significantly developed.
The trophoblast in the blastocyst primarily functions to facilitate implantation into the uterine wall.

Developmental Milestones

The fluid-filled cavity (blastocoel) appears during the blastocyst stage.
The trophoblast's secretion of protease and protein digestive enzymes assists in digesting the uterine lining for proper implantation.
Trophoblast typically attaches to the upper posterior part of the uterus.
Implantation usually occurs approximately 6 to 10 days after conception.
The process by which the blastocyst binds to and buries itself within the uterine wall is known as implantation.

Fertilization Processes

The primary function of hyaluronidase enzymes during fertilization is to help the sperm penetrate the outer layers of the ovum.
Fertilization typically takes place in the fallopian tubes of the female reproductive tract.
The fusion of sperm and ovum nuclei during fertilization creates a single-cell zygote with a complete set of chromosomes.
The term for the mitotic cellular replication process that occurs post-fertilization is cleavage.
The structure surrounding the morula, a solid ball of 16 cells, is known as the zona pellucida.

Cleavage and Amniotic Fluid

During the cleavage stage of fertilization, cell divisions occur approximately every 20-30 hours.
The primary component of the amniotic fluid is water, contributing to the hydration and protection of the developing fetus.

Fetal Development Highlights

The fetus's central nervous system begins to develop from the ectoderm by the end of the third week of gestation.
Fetal kidneys begin to function around the 10th week of gestation.
Near term, the primary function of the gastrointestinal system in the fetus is the processing of amniotic fluid and nutrient absorption.
The fetal brain reaches about 25% of the adult size at term, demonstrating significant development.

Sex Differentiation and Developmental Accessories

Distinguishing characteristics of sex differentiation appear in the embryo around 7-8 weeks of gestation.
The vernix caseosa serves as a protective coating on the fetal skin, preventing damage and water loss.
The fetus produces IgM immunoglobulins starting around the 20th week of gestation.
Fontanels, or soft spots on a baby's skull, allow for flexibility during birth and brain growth during infancy.
IgG immunoglobulins are significant for providing passive immunity to the fetus from the mother.
Toenails begin to develop around the 18th week of gestation.
Lanugo hair serves to help anchor the vernix caseosa to the skin and provides insulation for the fetus.

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Description

Test your understanding of the processes involved in sperm capacitation and fertilization, including the role of enzymes like hyaluronidase and the acrosomal reaction. Learn how sperm travel through the female reproductive tract and interact with the ovum.