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MCBM Exam 5 Kat > Gametogenesis & Fertilization > Flashcards

Gametogenesis & Fertilization Flashcards

1
Q

When are precursors of gametes recognizable by?

A

The 4th week of gestation

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2
Q

Where do primordial germ cells develop?

A

In the endoderm of the yolk sac

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3
Q

What do primordial germ cells associate with to form primordial gonads?

A

With somatic cells

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4
Q

What do primordial germ cells divide by?

A

Standard mitosis

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5
Q

What hypothalmic/pitutary influences affect male and female gametes?

A

Hypothalmus - GnRH
Pituitary - LH, FSH
Sex Steroids

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6
Q

What sex steroids are used in males and females?

A

Males use testosterone

Females use estrogen and progesterone

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7
Q

What is initiated by week 12?

A

Meiosis I, primary oocytes are beginning to develop, aquirered layer of epithelial cells called primordial follicles

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8
Q

What do follicular cells secrete?

A

OMI or oocyte maturation inhibitor which arrests the follicle at prophase I

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9
Q

How many oocytes at birth, puberty and maturity?

A

~2.5 million at birth
~70,000 at puberty
~400 at maturity

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10
Q

What does GnRH do to oocytes at puberty?

A

Increases FSH & LH secretion

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11
Q

What does FSH do to oocytes at puberty?

A

Stimulates follicle maturation; maturing oocyte termed “Graafian follicle”

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12
Q

What does LH do to oocytes at puberty?

A

Stimulates ovulation

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13
Q

What does Estrogen do to oocytes at puberty and what is it secreted by?

A

Secreted by follicular cells, stimulates maturation

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14
Q

What is Progesterone secreted by?

A

By the corpus luteum

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15
Q

At what stage are oocytes arrested at until the menstrual cycle?

A

They are arrested as primary follicles which is an oocyte plus a single columnar layer of epithelial cells.

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16
Q

What does an oocyte progress to during a menstrual cycle?

A

A secondary follicle which is a primary oocyte + zone pellucida and multi-layer epithelial cells

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17
Q

What does the innermost layer of the secondary follicle attach too?

A

The corona radiata attaches to the zona

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18
Q

What is the Zona pellucida made of?

A

3 glycoproteins (ZP 1,2,3)

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19
Q

What does the epithelial layer of the oocytes differentiate into?

A

Into the interna and external of the theca follicle.

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20
Q

What is the antrum?

A

Fluid filled cavity in center of follicle

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21
Q

What does the LH surge trigger?

A

Proteolytic breakdown of ovarian wall granulose-secreted enzymes

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22
Q

What prohibits the enzyme breakdown triggered by LH?

A

Theca cells

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23
Q

When does meiosis resume for oocytes?

A

Just prior to ovulation

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24
Q

What is OMI maintained by?

A

PK-A

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25
Q

What does the LH surge cause?

A

An increase in IP3 and Ca2++ in granlosa cells which is transmitted via gap junctions to oocyte

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26
Q

How does signaling for oocytes change when cAMP phosphodiesterase is increased?

A

[cAMP] goes down resulting in PK-A losing activation and OMI loses function. When PK-A mediation is shut off PK-C mediation begins.

27
Q

What is MPF?

A

Maturation Promoting Factor

28
Q

What does MPF target?

A

Nuclear laming and triggers germinal vesicle breakdown and completion of meiosis I.

29
Q

What increases MPF activity?

A

PK-C

30
Q

At what stage does the secondary oocyte arrest until fertilization?

A

Meiosis II, metaphase II

31
Q

Where are spermatogonia located?

A

As dormant cells in testicular seminiferous tubules

32
Q

What does GnRH do to spermatogenesis at puberty?

A

Increases FSH and LH

33
Q

What does FSH do to spermatogenesis at puberty?

A

Stimulates Serotoli cell secretion of androgen binding protein (ABP) and inhibin

34
Q

What does LH do to spermatogenesis at puberty?

A

Stimulates Leydig cell secretion of testosterone

35
Q

What do testosterone and DHT do to spermatogenesis at puberty?

A

Stimulate final steps of spermatogenesis

36
Q

How many lobules and seminiferous tubules are in the testes?

A

2-300 lobules each with 2-3 seminiferous tubules

37
Q

How does Sperm Differentiate?

A

Histones replaced by protamines; intensive condensation
Golgi builds acrosomal
Axoneme organizes flagella

38
Q

What type of genome does spermiogenesis require?

A

A diploid hormone

39
Q

How long does it take for the differentiation process of converting spermatids to mature sperms take?

A

~64 days total

40
Q

How many mature sperm are produced each day?

A

~300 million

41
Q

Are sperm and egg cells large or small?

A 
Sperm = small
Egg = huge
42
Q

Are sperm and egg cells motile or immotile?

A 
Sperm = motile
Egg = nonmotile
43
Q

Do sperm and egg cells have accessory cells?

A 
Sperm = no
Egg = Yes
44
Q

Do sperm and eggs have lots of cytoplasm or sparse cytoplasm?

A 
Sperm = sparse
Egg = Lots
45
Q

How many types of sperm and egg cells are there?

A 
Sperm = 2 types: 23X, 23Y
Egg = 1 Type: 23X
46
Q

How do oocytes go from the the ovaries to the fallopian tube?

A

Oocyte and follicular fluid are swept in the fallopian tube via fimbriae and mucosal cell cilia

47
Q

How does the oocyte get move toward the ampulla of the fallopian tube?

A

Via peristaltic waves

48
Q

Define emission in terms of sperm transport?

A

Semen is delivered to posterior urethra via peristalsis of ductus deferens

49
Q

Define ejaculation.

A

Semen is expelled through urethra via bulbospongiosus muscle contractions

50
Q

How much volume is expelled during ejaculation and what is the approximate sperm concentration?

A

About 2.5 - 5 ml with a sperm concentration of 50-150 x 10^6 / ml

51
Q

Where do the components of seminal fluid come from?

A

60% - seminal vesicles
25% - prostate
10% - bulbourethral (Cowper’s) gland

52
Q

What do the seminal vesicles contribute to seminal fluid?

A

Fructose
Prostaglandins
Unique clotting proteins

53
Q

What does the prostate contribute to seminal fluid?

A

Citrate

Prostate specific antigen (PSA)

54
Q

What does the Cowper’s gland contribute to seminal fluid?

A

Buffer

Mucous

55
Q

What happens in post ejaculation sperm maturation?

A

Capacitation

56
Q

What happens in capacitation?

A

Acrosome is cleared of glycoprotein coat and seminal proteins
Sperm become more actively motile

57
Q

What is capacitation dependent on and who long does it take?

A

Calcium dependent

Takes 7-10 hours

58
Q

What happens post-fertilization?

A

Oocyte completes 2nd meiotic division and female and male pronuclei form
Sperm parts breakdown
Pronuclei breakdown
Mitotic spindle organizes using centriole components from sperm tail; chromosomes arrange on spindle
Mitosis begins

59
Q

What are some ways to assist fertilization?

A

IVF: in vitro fertilization
GIFT: gamete intrafallopian transfer (sperm + egg transfer)
ICSI: intracytoplasmic sperm injection (sperm only transfer)

60
Q

What are some reasons for male infertility?

A

Sperm count
Sperm motility
Sperm morphology

61
Q

What sperm count threshold is considered to be infertile?

A

< 20 X 20 ^6 / ml

62
Q

What is preimplantation genetic diagnosis (PGD) via blastomere dissection used for?

A

For diagnosis of heritable disease in 8-cell embryo

63
Q

What is the “manster” test?

A

Tests the ability of human sperm to penetrate zone-free hamster egg

MCBM Exam 5 Kat (15 decks)

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