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Endocrinology > Reproductive endocrinology > Flashcards

Reproductive endocrinology Flashcards

1
Q

When does oogenesis begin, complete and cease?

A

Begins in utero, is suspended for many years and resumes at puberty

Completes with fertilisation

Ceases with menopause

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2
Q

What is oogonia?

A

Completion of last pre-meiotic division to oocytes

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3
Q

What happens at the start of each menstrual cycle to the primordial follicles?

A

Several follicles enlarge and a cavity forms around the ovum within the follicle called antrum formation

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4
Q

What is contained within each primordial follicle?

A

An immature ovum

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5
Q

What is the cavity around the ovum within the follicle during antrum formation filled with?

A

Follicular fluid

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6
Q

During which day of the menstrual cycle does a dominant follicle become apparent?

A

6th

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7
Q

What is the dominant follicle in menstruation?

A

At the start of the cycle, several follicles enlarge

One follicle in one ovary tends to grow more rapidly than the others in the first 6 days

The others regress, becoming atretic follicles

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8
Q

What is the first half of the menstrual cycle called?

A

Follicular phase

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9
Q

What happens during the follicular phase?

A

Maturation of egg, ready for ovulation at midcycle

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10
Q

What signals the end of the follicular phase?

A

Ovulation

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11
Q

What is the primary source of circulating estrogen?

A

The granulosa cells of the ovaries

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12
Q

At birth, what is the primary oocyte surrounded by?

A

A single layer of granulosa cells

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13
Q

What is a primary follicle?

A

The primary oocyte surrounded by a single layer of granulosa cells

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14
Q

How does the primary follicle become the secondary follicle?

A

Oocyte grows (x1000) and follicle expands and becomes differentiated under hormonal influence

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15
Q

What happens on about the 14th day of the cycle after the mature follicle has formed and the dominant follicle apparent?

A

The distended follicle ruptures and released the ovum into the abdominal cavity

This is ovulation

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16
Q

What happens to the ovum that has been ovulated into the abdominal cavity?

A

Picked up by the fimbrae of the uterine tube (oviducts) and transported along to the uterus and out through the vagina

(Unless fertilisation occurs)

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17
Q

What happens to the follicular cells left behind after ovulation?

A

Undergo lutenization to form the corpus luteum

18
Q

What hormone does the corpus luteum secrete?

A

Progesterone

19
Q

What is the main hormone secreted during the follicular phase?

A

Oestrogen

20
Q

How long does the corpus luteum grow after ovulation?

A

For 8-9 days

21
Q

What event signals the start of a new follicular phase?

A

The degeneration of the corpus luteum

It will survive no longer than 14 days after ovulation

22
Q

What is growth of the corpus luteum dependant on?

A

Developing a blood supply

23
Q

What happens to the corpus luteum if pregnancy occurs?

A

It persists and it secretes increasing quantities of oestrogen and progesterone until after delivery

24
Q

At what time do ova undergo the first part of the first meotic division and what happens after this?

A

At birth

There are roughly 2 million ova at this point, with 50% being atreic

The normal ones undergo the first part of the first meiotic division, and arrest in prophase in which those that survive persist into adulthood

25
Q

At what time do ova complete the first meiotic division?

A

Just before ovulation

26
Q

What happens to the daughter cells of the first meiotic division?

A

One, the secondary oocyte, recieves most of the cytoplasm

The other, the first polar body, fragments and disappears

27
Q

When does the start of the second meiotic division occur and in which cells?

A

The second meiotic division only occurs in the secondary oocyte: the surviving daugther cell from the first meiotic division

Second meiotic divison occurs almost immediately after the first, but is arrested at metaphase

28
Q

When is the second meiotic division completed?

A

When a sperm penetrates the oocyte

This casts off the second polar body and the fertilised ovum proceeds to create a baby

29
Q

Which hormone stimulates the anterior pituitary to produce ovarian hormones?

A

GnRH

30
Q

What are the reproductive hormones that the anterior pituitary secretes?

A

FSH

LH

31
Q

What does FSH do?

A

Acts on ovary
Stimulates development of follicles
FSH + LH stimulate secretion of oestradiol and ovulation

32
Q

What does LH do?

A

Acts on ovary

Stimulates follicle maturation, ovulation and development of the corpus luteum

FSH + LH stimulate secretion of oestradiol and ovulation

33
Q

What happens in the hypothalamus when the follicular phase begins?

A

Hypothalamus secretes GnRH

Ant pituitary secretes FSH and a little LH

Up to 15 follicles begin to mature and form granulosa cells and theca cells

Oestrogen suppresses FSH production by the ant. pituitary (selection of dominant follicle)

34
Q

What is the role of the theca cells and granulosa cells during the follicular phase?

A

The theca cells produce androgen which is converted by the granulosa (aromatase) to oestradiol (thickens endometrium/thins cervical mucus)

35
Q

What happens in the hypothalamus once the dominant follicle has been selected?

A

Granulosa in the dominant follicle express LH receptor

High levels of oestrogen at mid cycle cause hypothalamus to release GnRH

Causes FSH and LH surge from ant. pituitary

36
Q

What happens to the levels of LH and FSH during ovulation?

A

They fall

37
Q

What happens to the remaining granulosa during the luteal phase?

A

Become part of the corpus luteum and secrete progesterone

38
Q

What happens to thecal cells during the luteal phase?

A

Convert androgen to oestrogen

39
Q

What happens 12 days into the luteal phase to oestrogen and progesterone levels?

A

If there is no hCG production from an embryo, the corpus luteum degenerates forming the corpus albicans

This reduces the levels of oestrogen and progesterone, starting the cycle again by removing negative feedback

40
Q

At which stage of pregnancy does the corpus luteum degenerate to the corpus albicans?

A

6 weeks - the placenta takes over the function of secreting progesterone

Endocrinology (12 decks)

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