Flashcards in Folliculogenesis Deck (37)
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1

What are the 4 things required for reproduction?

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

2

What are cells that will become egg or sperm called?

β†’ Primordial germ cells

3

When are PGCs first identifiable?

β†’ in the yolk sac 3 weeks after conception

4

What happens to the PGCs?

β†’ the cells undergo many cycles of mitosis
β†’ They migrate to the genital ridge

5

What does the genital ridge become?

β†’ The gonad

6

What does further differentiation of the PGCs depend on?

β†’ The development of the gonad

7

What do germ cells become when in the ovary?

β†’ oogonia

8

What are oogonia?

β†’ Egg precursors

9

When oogonia enter meiosis what are they known as?

β†’ Primary oocytes

10

What phase do primary oocytes remain in and until when?

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

11

Describe mitosis briefly?

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

12

Describe meiosis

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

13

where are primary oocytes packed?

β†’ Outer layer of the ovary : cortex

14

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

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

15

What do granulosa cells secrete?

β†’ Acellullar layer called the basal lamina

16

What does a primordial follicle consist of?

β†’ Oocyte with granulosa cells and a basal lamina

17

What do germ cells become in the ovary?

β†’ oogonia

18

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

β†’ Diploid
β†’ Multiply by mitosis

19

What happens to the follicles at puberty and at menopause?

β†’ Follicles start growing at puberty
β†’ arrests at menopause

20

What is folliculogenesis defined as?

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

21

What happens as the follicles start to grow?

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

What are theca cells and what is their purpose?

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

23

What drives most of folliculogenesis?

β†’ FSH

24

What happens to follicles when FSH is suppressed?

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

25

What happens in the second stage of follicle growth?

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

What are the two main phases of follicular growth?

β†’ Absence or presence of the antrum

27

What are follicles with an antrum known as?

β†’ antral or secondary follicles

28

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

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

29

Describe how primordial follicles physically change to become Graffian follicles

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

What are the cells directly surrounding the oocyte called?

β†’ Corona radiata