Fertilization and Embryology

Flashcards on Fertilization and Embryology

What is Fertilization?

The process where fimbria direct ova into the Fallopian tube after ovulation.

How does the ova move towards the uterus?

Muscular contractions and cilia movement.

How long does it take for the ova to reach the uterus?

Approximately four days.

How long will the ova survive if not fertilized?

12-24 hours.

What causes many sperm to die after ejaculation?

Acidity of the vagina and entering the wrong oviduct.

How many chromosomes are in a male sperm and female egg cell?

23 chromosomes.

How many chromosomes are in a fertilized egg?

46 chromosomes.

What is the zona pellucida?

Clear layer of protein and carbohydrates that surrounds the plasma membrane.

What is the corona radiata?

Jelly-like layers of follicle cells from the follicle.

What happens when sperm meets egg?

Acrosome releases enzymes to digest the corona and zona pellucida.

How is the fertilization process completed?

The zygote results from the fusion of 23 sperm chromosomes and 23 egg chromosomes, totaling 46 chromosomes

What is a zygote?

The first cell of life.

What is cleavage?

Cell division without growth.

What happens when the zygote divides into 16 cells?

Morula.

What happens 3 to 5 days after fertilization?

The morula reaches the uterus.

What is the trophoblast?

Outer cells of the blastocyst that form the chorion and placenta.

What is the embryoblast?

Inner cell mass/inner cluster of cells of the blastocyst that develops into embryo and then fetus.

How many days after fertilization does the blastocyst attach to the endometrium?

5 to 7 days.

How many days after fertilization does the blastocyst sink into the endometrium (implantation)?

10 to 14 days.

What is HCG?

Human chorionic gonadotropin; secreted by the trophoblast when implantation starts.

How does a pregnancy test work?

Detects minute amounts of hCG in urine and blood.

What happens during gastrulation during week 2?

Space forms between inner cell mass and trophoblast.

What are the three primary germ layers formed during gastrulation?

Ectoderm, endoderm, and mesoderm.

What is gastrulation?

The process of forming three layers.

What does the ectoderm form?

Nervous system, epidermis.

What does the mesoderm form?

Skeleton, muscles, reproductive structures.

What does the endoderm form?

Lining of the digestive and respiratory systems, endocrine glands.

What are the extra embryonic membranes

Allantois, amnion, chorion, and yolk sac.

What do Extra embryonic membranes + placenta + umbilical chord provides for the embryo (and fetus)?

provides protection, nutrition, respiration, and excretion for embryo (and fetus)

What is the chorion?

Outermost membrane, encloses embryo and contributes to placenta.

What are chorionic villi?

Vascular projections of the chorion, visible after 2 weeks.

What is the amnion?

Fluid-filled sac-protects embryo from trauma, maintains consistent temperatures, and prevents limbs from sticking to body.

What is the allantois?

Forms umbilical chord then becomes urinary bladder.

What is the placenta?

Disk-shaped organ rich in blood vessels where metabolic exchange happens.

Why should the placenta avoid alcohol, drugs, and nicotine ?

Because alcohol drugs and nicotine can diffuse across and harm them

What is the umbilical cord?

Connects fetus to placenta.

What is an embryo?

Period of morphogenesis, most of the organs are taking shape.

What is a fetus?

Time of growth and refinement of structures.

What does the mesoderm thickens along back of embryonic disc becomes?

Notochord.

When does mom feels movement in the 2nd trimester

Month 5.

Name some known teratogens.

Cigarette smoke, alcohol, drugs

What are teratogens?

Any agent that causes a structural abnormality.

What is parturition (labor)?

The birthing process is called what?

What are the stages of parturition?

Dilation, expulsion, and placental.

What is a Caesarean section?

Physician makes incision in mom's abdomen and uterus to remove baby.

What is lactation?

Secretion and formation of breast milk in the mother.

What is prolactin?

Hormone needed for milk production.

What does oxytocin do in lactation?

Stimulates milk release.