1
Q

What are the 4 things required for reproduction?

A

β†’ Differentiation into male or female
β†’ Sexual maturation
β†’ Production, storage and release sufficient supply of eggs and sperm
β†’ correct number of chromosomes in eggs and sperm
β†’ egg and sperm have to meet

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2
Q

What are cells that will become egg or sperm called?

A

β†’ Primordial germ cells

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3
Q

When are PGCs first identifiable?

A

β†’ in the yolk sac 3 weeks after conception

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4
Q

What happens to the PGCs?

A

β†’ the cells undergo many cycles of mitosis

β†’ They migrate to the genital ridge

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5
Q

What does the genital ridge become?

A

β†’ The gonad

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6
Q

What does further differentiation of the PGCs depend on?

A

β†’ The development of the gonad

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7
Q

What do germ cells become when in the ovary?

A

β†’ oogonia

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8
Q

What are oogonia?

A

β†’ Egg precursors

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9
Q

When oogonia enter meiosis what are they known as?

A

β†’ Primary oocytes

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10
Q

What phase do primary oocytes remain in and until when?

A

β†’ They remain in the first phase of meiosis until it ovulates or dies

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11
Q

Describe mitosis briefly?

A

β†’ Spindle is formed
β†’ The chromatids are lined up one behind the other
β†’ They then separate to opposite poles of the cell
β†’ The cytoplasm divides and there are two identical cells

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12
Q

Describe meiosis

A

β†’ Duplication of the chromatids
β†’ They line up adjacent to each other
β†’ Chromosome 1 lines up with chromosome 1 from the other parent
β†’ allows crossing over and biological variation
β†’ homologous chromosomes separate into two haploid cells
β†’ separate again to form gametes
β†’oocytes are arrested in meiosis 1 until LH surge

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13
Q

where are primary oocytes packed?

A

β†’ Outer layer of the ovary : cortex

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14
Q

What do the cells around the oocyte become in the fetal ovary?

A

β†’ Condense around the oocyte and differentiate into granulosa cells

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15
Q

What do granulosa cells secrete?

A

β†’ Acellullar layer called the basal lamina

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16
Q

What does a primordial follicle consist of?

A

β†’ Oocyte with granulosa cells and a basal lamina

17
Q

What do germ cells become in the ovary?

A

β†’ oogonia

18
Q

What type of cell are oogonia and how do they multiply?

A

β†’ Diploid

β†’ Multiply by mitosis

19
Q

What happens to the follicles at puberty and at menopause?

A

β†’ Follicles start growing at puberty

β†’ arrests at menopause

20
Q

What is folliculogenesis defined as?

A

β†’ Growth and development of follicles from the earliest resting stages as laid down in the fetus through to ovulation

21
Q

What happens as the follicles start to grow?

A

β†’ Granulosa cells multiply
β†’ Granulosa cells secrete basal lamina around it
β†’ oocyte secretes another protective acellular layer called the zona pellucida
β†’ Theca cells differentiate around the basal lamina

22
Q

What are theca cells and what is their purpose?

A

β†’ Steroid producing

β†’ they sustain the growth of the follicle and the oocyte

23
Q

What drives most of folliculogenesis?

A

β†’ FSH

24
Q

What happens to follicles when FSH is suppressed?

A

β†’ The follicles will continue early growth but they die

25
Q

What happens in the second stage of follicle growth?

A

β†’ Increases rapidly in diameter
β†’ Granulosa cell divisions increase but gaps form in the cell layers
β†’ gaps form an antrum filled with follicular fluid

26
Q

What are the two main phases of follicular growth?

A

β†’ Absence or presence of the antrum

27
Q

What are follicles with an antrum known as?

A

β†’ antral or secondary follicles

28
Q

What kind of cells do primordial follicles have and how do they look and grow?

A

β†’ flattened granulosa cells
β†’ grow in a slow and controlled manner
β†’ become cuboidal in shape

29
Q

Describe how primordial follicles physically change to become Graffian follicles

A

β†’ Granulosa cells
β†’ FSH causes granulosa cells to proliferate and the zona pellucida forms around the oocyte
β†’ theca cells are produced around the granulosa cells
β†’granulosa cell divisions increase and gaps form which are filled with follicular fluid
β†’these join and form the antrum
β†’ the egg is then within follicular fluid

30
Q

What are the cells directly surrounding the oocyte called?

A

β†’ Corona radiata

31
Q

Where are primordial cells arrested in?

A

β†’ Meiosis I

32
Q

What is follicle initiation?

A

β†’ When a cohort of follicles leave the resting pool and grow continuously

33
Q

What is follicle recruitment?

A

β†’ When the follicles are big enough to respond to changes FSH they start growing

34
Q

What do follicles need to continue growing?

A

β†’ FSH

35
Q

How long does the follicular phase last?

A

β†’ 14-15 days

36
Q

What is atresia?

A

β†’ When follicles die

37
Q

What steroids do the granulosa and theca cells produce?

A

β†’ Theca produces androgens which is stimulated by LH

β†’ androgens go to granulosa and get converted to estrogen which is stimulated by FSH