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Fundamental Processes And Gametogensis Flashcards

1
Q

What is the most sensitive time for induction of a birth defect?

A

Embryonic period (3-8 weeks)

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2
Q

What weeks are the embryonic period?

A

Weeks 3-8

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3
Q

At which levels is gene expression regulated?

A

Regulation of gene transcription
Regulation of selective mRNA translation
Differential Protein Modification

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4
Q

Describe the epithelial-mesenchymal interaction

A

Differentiation of undifferentiated tissue into specialized organ

-initial signal from first tissue induces second tissue to differentiate

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5
Q

What is the term for the first tissue in an epithelial - mesenchymal interaction?

A

Inducer

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6
Q

What is the term for the second tissue in an epithelial - mesenchymal interaction?

A

Responder

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7
Q

True or false: once the induction process is initiated, signals are transmitted in both directions to complete the differentiation process

A

True

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8
Q

Which pathway does the paracrine signaling use?

A

Signal Transduction pathway

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9
Q

What is another term for paracrine factors?

A

Growth and differentiation factors (GDFs)

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10
Q

Describe the standard signal transduction pathway

A

Ligand binds to its receptor
Activation of an enzyme
Phosphorylation cascade of several proteins
Activation of transcription factor that initiates gene expression

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11
Q

What are the four different families of paracrine factors?

A

FGF
SHH
WNT
TGF-B

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12
Q

What is the FGF paracrine factor?

A

Fibroblast growth factor

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13
Q

What does the FGF paracrine factor do?

A

Produce hundreds of protein isoforms by alternative splicing

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14
Q

What is the SHH paracrine factor?

A

Sonic HedgeHog

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15
Q

What does the SHH paracrine factor do?

A

Sonic HedgeHog involved in developmental events - master gene for embryogenesis

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16
Q

What does the WNT paracrine factor do?

A

Regulating limb patterning, midbrain development, somite and urogenital differentiation

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17
Q

What is the TGF-B paracrine factor?

A

Transforming Growth Factor - beta

A superfamily

18
Q

What does the TGF-B paracrine factor do?

A

A super family
Important for extra cellular matrix formation,
Epithelial branching in kidney
Salivary gland development

19
Q

Describe juxtacrine signaling

A

A protein on one cell surface binds to receptor on adjacent cell
- does not involve diffusible factors -

20
Q

True or False: juxtacrine signaling is best described as direct transmission of signals through gap junctions

21
Q

Describe autocrine signaling

A

Cells secrete signaling molecule that binds to one of its own receptors leading to cellular change/response

22
Q

Define gametogenesis

A

Production of gametes through meiosis

23
Q

What is the term for production of female gametes?

24
Q

What is the term for production of male gametes?

A

Spermatogenesis

25
Q

How many chromosomes are inside a primary oocyte or primary spermatocyte?

A

46 double-structured chromosomes

26
Q

How many chromosomes are in a secondary oocyte or spermatocyte?

A

23 double-structured chromosomes

27
Q

How many chromosomes are in an ovum or spermatid?

A

23 single chromosomes

28
Q

Describe generally the result of meiosis I

A

A primary oocyte spermatocyte splits from 46 double structured chromosomes to 23 double-structured chromosomes

29
Q

Describe generally the result of Meosis II

A

A secondary oocyte/spermatocyte split from 23 double-structured chromosomes to 23 single chromosomes

30
Q

What are polar bodies?

A

A result of oogensis as meiosis I and meiosis II remove half of chromosomes and are discarded

31
Q

True or false: Polar bodies are a result of oogenesis only and are not created in spermatogenesis

32
Q

What are the types of abnormal meitotic division?

A

Nondisjunction in meiosis I

Nondisjunction in meiosis II

33
Q

In what phases is oogenesis arrested?

A

Prophase in Meiosis I

34
Q

At what point in life does oogenesis continue?

A

Puberty - one primary oocyte at a time

35
Q

Describe the continuation of oogenesis once it is unpaused

A

At puberty, a primary oocyte per ovarian cycle will complete meiosis I and enter Meiosis II and arrest in metaphase

36
Q

At what point does meiosis II continue for a secondary oocyte?

A

Fertilization by sperm

37
Q

In what stage is a secondary oocyte paused?

A

Metaphase of Meiosis II

38
Q

Define spermatogenesis

A

Events by which spermatogonia transform into spermatozoa

39
Q

How many days for spermatogonium to develop into mature spermatozoon?

A

Approx 74 days

40
Q

What are examples of abnormal oocytes?

A

Primordial follicle with two ooctyes- sometimes results in twins
Trinucleated oocyte - never survives

41
Q

What are examples of abnormal spermatozoa?

A 
Double head
Double tail
Short tail
Rounded head
**all naturally selected against and will not fertilize an egg

Embryology (2 decks)

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