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Maternity Exam 1 > Fetal Development and Genetics > Flashcards

Fetal Development and Genetics Flashcards

1
Q

What is oogenesis?

A
  • Process by which female gametes, or ova (eggs), are produced in the ovaries
  • Begins before female fetus is born
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2
Q

Describe oogenesis in the female fetus.

A

start to undergo first meiotic division to replicate DNA, but stop before it’s finished

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3
Q

Describe oogenesis once puberty starts.

A
  • hormonal changes stimulate the development of ovarian follicles
  • each month (q28 days) 1 ooccyte completes first meiotic division
  • results in:
    • secondary oocyte (released during ovulation)
    • small polar body (usually non-functional)
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4
Q

Describe oogenesis during ovulation.

A
  • secondary oocyte is released from the ovary during ovulation
  • if fertilization occurs, it will proceed to complete meiosis II
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5
Q

What is Spermatogenesis?

A

sperm formation

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6
Q

What is Spermatogonium?

A

primitive sperm cells (male gametes) produced in the testes at onset of puberty

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7
Q

Describe spermatogenesis during Meiosis I.

A
  • primary spermatocyte undergoes meiosis I, resulting in two secondary spermatocytes
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8
Q

Describe spermatogenesis during Meiosis II.

A
  • results in a total of two haploid spermatids from one secondary spermatocyte
  • each primary spermatocyte, four sperms are produced
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9
Q

What is an ovum and where is it developed?

A
  • mature egg released from the ovary during ovulation
  • develops within a structure called the follicle
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10
Q

What is the function of fimbriae?

A
  • finger-like projections at the end of the fallopian tubes
  • after ovulation, they help capture the released ovum and guide it into the uterine tube (fallopian tube) for potential fertilization
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11
Q

What is the corpus luteum and what does it do?

A
  • the remnants of the mature follicle transform into the corpus luteum
  • secretes progesterone (a hormone used to prepare the endometrium (uterine lining) for possible fertilized egg)
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12
Q

What are the two protective layers of the ovum?

A
  • Zona Pellucida: surrounds the ovum, helping to protect the egg and facilitating the binding of sperm
  • Corona Radiata: surround the zona pellucida and provide support and nutrients to the ovum.
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13
Q

How long does the ovum have before needing to be fertilized?

A
  • about 24 hours after it is released
  • after, it degenerates and gets absorbed into body or expelled during menstrual cycle
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14
Q

Describe quantity of sperm.

A

1tsp of semen = 200-500 million sperm

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15
Q

What does the tail of the sperm do?

A
  • the flagellum is responsible for its motility, allowing it to swim toward the ovum
  • contains mitochondria, which provide the energy (ATP) needed for movement.
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16
Q

What is the purpose of the head of the sperm?

A
  • contains enzymes stored in a structure called the acrosome
  • crucial for breaking down the zona pellucida, which allows for fertilization
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17
Q

How long does sperm have to reach the ovum?

A

remain viable and capable of fertilization for up to 5 days after ejaculation

18
Q

What happens when sperm reaches ovum?

A
  • meet in ampulla (outer third) of the uterine tube
  • zona reaction (chemical reaction) prevents more than one sperm from entering the ovum
  • restores the diploid number (23+23=46) to form zygote (fertilized egg)
19
Q

What is the greatest risk for an embryo (until 8 weeks)?

A

Teratogens
- Infections: Rubella, toxoplasma, TORCH
- Environmental exposures: heat, toxins
- Chemical exposures: alcohol, medications

20
Q

How does the placenta form?

A
  • derived from the trophoblast cells of the blastocyst (outer layer of embryo)
  • 2 layers:
    • Syncytiotrophoblast: outer layer, invades uterine lining and establishes the maternal-fetal connection
    • Cytotrophoblast: inner layer, provides support and structure
21
Q

How does circulation occur within the placenta?

A
  • begins around day 17
  • large network of blood vessels that invades maternal circulation through the uterine lining
22
Q

How does embryonic blood circulation occur within the placenta?

A
  • occurs by day 21
  • Intervillous spaces (allow for efficient exchange of substances)
  • Maternal blood provides oxygen and nutrients
  • Exchanges waste and carbon dioxide from the fetus
23
Q

How does the placenta contribute to endocrine and immune barrier function?

A
  • Endocrine: placenta produces hormones (human chorionic gonadotropin (hCG), progesterone, estrogen), which maintains pregnancy and supports fetal development
  • Immune Barrier (Semipermeable Membrane): placenta acts as a barrier that protects the fetus from certain pathogens while allowing the passage of antibodies and some immune cells from the mother to provide passive immunity
24
Q

Describe the mother’s side of the placenta.

A
  • rough and convoluted
    • due to the presence of decidual tissue and maternal blood vessels
  • Dull red in color due to maternal blood
    • vascularized with maternal blood, which is essential for providing oxygen and nutrients
25
Q

Describe the fetus’s side of the placenta.

A
  • shiny and smooth
    • prevent adhesion to surrounding tissues and facilitates movement
26
Q

Describe placenta’s growth.

A
  • placenta grows in thickness and circumference until week 16
    • after, only grows in circumference
  • weighs about 1lb at term
27
Q

Describe the blood inside the placenta.

A
  • Contains approx. 500mL of blood at term
  • Blood in the intervillous space is replenished 3-4 times every minute
28
Q

What is amniotic fluid?

A

clear, slightly yellowish liquid that surrounds and cushions the developing fetus

29
Q

What produces amniotic fluid and how much?

A
  • fetal kidneys and lungs (at 10 weeks)
  • at term, 1000mL
30
Q

What are the functions of amniotic fluid?

A
  • Maintains constant temperature
  • Cushions fetus
  • Allows movement and development
  • Provide vitamins, proteins, IgG, electrolytes
  • Antibacterial properties
  • Important to fetal lung development
31
Q

Describe the umbilical cord.

A
  • 3 vessels (AVA)
    • 2 arteries – return blood to the placenta/chorionic villi
    • 1 vein – carries nutrient and oxygen rich blood to the embryo/fetus
  • 30-90 cm in length, average 55cm
  • Covered with Wharton’s jelly
  • Centrally attached to the placenta
  • Develops from the connecting stalk
32
Q

What are Autosomal Chromosomal Abnormalities?

A
  • involve changes in the non-sex chromosomes and can lead to a wide range of genetic disorders
  • characterized by developmental and physical challenges
    • Trisomy 21 (down syndrome)
33
Q

What are Sex Chromosomal Abnormalities?

A
  • changes in the X and Y chromosomes, affecting sexual development and function
  • varied effects on physical and reproductive health
    • Turner syndrome (45, X)
34
Q

Describe multifactorial inheritance.

A
  • Most common congenital conditions
  • affects multiple genes and environmental interactions
  • Examples: cleft lip, cleft palate, congenital heart disease
35
Q

Describe unifactorial inheritance.

A
  • caused by mutations in a single gene
  • follows clear Mendelian inheritance patterns with predictable risks
36
Q

List the types of genetic tests used in the perinatal period.

A
  • Alpha-Fetoprotein (AFP)
  • Cell-free DNA
  • Fetal nuchal translucency (FNT)
  • Preimplantation genetic testing
  • Triple & Quad Screening
37
Q

Describe Alpha-Fetoprotein (AFP), indications, and timing.

A
  • Description: Maternal serum
  • Indication: Increased levels associated with neural tube defect
  • Timing: Between 15-18 weeks
38
Q

Describe Cell-free DNA, indication, and timing.

A
  • Description: Maternal plasma.
  • Indication: Fetal sex, genotyping, Trisomy 13, 18, 21
  • Timing: Approximately 10 weeks
39
Q

Describe Fetal nuchal translucency (FNT), indication, and timing.

A
  • Description: Vaginal probe ultrasound to measure fluid collection at base of fetal neck
  • Indication: Associated with genetic disorders, trisomy 13, 18, 21, Turners syndrome
  • Timing: Between weeks 10-14
40
Q

Describe Preimplantation genetic testing, indication, and timing.

A
  • Description: Genetic testing of embryos produced through IVF.
  • Indication: Identify genetic alterations prior to implantation
  • Timing: 3 days after egg retrieval or 2 days after fertilization
41
Q

Describe Triple & Quad Screening, indication, and timing.

A
  • Description: Maternal serum measure of AFP, estriol, beta-HCG and inhibin A.
  • Indication: Identify risk for Down syndrome, NTD, other trisomy conditions
  • Timing: Between weeks 15-18

Maternity Exam 1 (5 decks)

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