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Reproduction > Reproductive Endocrinology > Flashcards

Reproductive Endocrinology Flashcards

1
Q

What are steroid hormones synthesised from? Where are they produced in females?

A

Cholesterol. They are synthesised in the gonads, adrenal glands and placenta.
Occurs primarily in the smooth ER and mitochondria.

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2
Q

What are peptide hormones synthesised from?

A

Amino acids.

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3
Q

Name circulating oestrogens? Where are they produced?

A

Oesteone: Secreted directly from the ovary or converted from androstenedione.
Oestradiol: Produced by the ovary, directly synthesised in developing follicles or through conversion of oestrone.

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4
Q

What androgens does the ovary make?

A

Androstenediol, DHEA and small amounts of testesterone (converted to oestradiol by aromatase).

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5
Q

What androgens does the adrenal gland produce in females?

A 
Adrenal cortex
25% of testesterone
50% Androstenedione
90% DHEA
100 % of sulfated DHEA.
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6
Q

How are progestins produced in females?

A

From cholesterol via pregnenolone.

Produced mainly in corpus leuteum, the adrenal glands and placenta.

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7
Q

What is congenital adrenal hyperplasia?

A

21-hydroxylase deficiency. Causes ambiguous genitalia, anovulation.

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8
Q

What is aromatase deficiency?

A

Prevents oestrogen synthesis. Ambiguous genitalia.

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9
Q

What is aromatase excess?

A

Excessive conversion of androgens and oestrogens.

Feminism of male genitalia.

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10
Q

What is the hypothalamic-pituitary-ovarian axis?

A

How female reproduction is regulated.
Hypothalamus secreted GnRH which stimulates the anterior pituitary to release FSH and LH.
The ovary (& placenta) respond to levels of GnRH and secrete steroid sex hormones.

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11
Q

What type of hormone is GnRH? How is it secreted?

A

Peptide hormone.

Neurosecretory cells of the hypothalamus into the hypophyseal-portal system in a pulsatile manner.

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12
Q

What is the function of FSH in females?

A

Initiates follicle recruitment and supports its growth - especially the granulosa cells.

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13
Q

What does LH do in females?

A

Supports the theca cells. LH surge triggers ovulation.

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14
Q

What is the ‘follicular phase’?

A

Day 0-14 Pre-ovulation stage of the menstrual cycle. Characterised by growth of a dominant follicle. Endometium is proliferating (proliferative phase).

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15
Q

What is the luteal phase?

A

Day 14-28 Post-ovulation. In the endometrium this is the secretory phase.

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16
Q

Why does progesterone increase after ovulation in the menstrual cycle?

A

The corpus leuteum forms after ovulation, it produces P causing the endometrium to become spongy and full of glands. If no pregnancy, corpus luteum dies and levels drop.

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17
Q

What factors cause a primordial follicle to mature to a primary follicle? Where do they come from?

A

BMP 4 & 7: From stromal cells acting on the oocyte.

bFGF and K: From the oocyte acting on stromal cells.

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18
Q

Describe the structure of a primordial follicle?

A

1 layer of follicular cells.

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19
Q

Describe the structure of a primary follicle?

A

Follicular cells divide. Zona pellucida forms.

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20
Q

Describe the structure of a secondary follicle?

A

Theca develops and gets an independent blood supply.
Granulosa calls develop FSH, oestrogen and androgen receptors.
Large fluid filled antrum.
Increased oestrodiol production via conversion of androgens produced in the theca interna to oestrogens by the granulosa cells (aromatase).

21
Q

What produces inhibin in females?

A

Developing follicles - it causes inhibition of FSH.

22
Q

List the uterine changes in the proliferative phase? What causes this?

A

Thickening of stroma
Elongation of uterine glands
Growth of spiral arteries.

Caused by oestrogens from ovary acting on endometrium.

23
Q

Describe the process of ovulation?

A

At the end of the proliferative phase, rising oestrogens increase responsivness of the pituitary to GnRH and cause a surge of hypothalamic GnRH secretion.
High oestrodiol triggers LH secretion.
LH surge stimulates enzymes that initiate breakdown of the follicle wall and release the mature oocyte.
LH surge also triggers completion of the first meiotic division.

24
Q

What stimulates development of secretory endometrium?

A

Progesterone.

25
Q

What is a corpus albucans?

A

Degenerated corpus leutum.

26
Q

What supports the corpus leutum if fertilisation occurs?

A

HCG produced by the developing embryo.

27
Q

Describe the process of menstruation?

A

Inhibin inhibits gonadotrophin secretion. This results in regression of the corpus luteum and reduction in progeterone.
Leukocytes infiltrate the endometrium.
Constriction and breakdown of spiral arteries causes tissue ischemia.
The pressure on the arteries is released and blood flows out to clear necrotic tissue.
This happens in patches around the uterus - The stratum functionalis (compactum and spongiosum) is lost, but the stratum basalis remains to regenerate this layer for the next cycle.

28
Q

How does vaginal epithelium change throughout the menstrual cycle?

A

Early follicular phase when oestrogen is low, the vaginal epithelium is thin and pale. As oestrogen increases in the follicular phase, squamous cells mature and epithelium thickens.
In the luteal phase, mature squamous cells shed as cellular debris.

29
Q

How does the cervix change throughout the menstrual cycle?

A

In the late follicular phase there is increased vascularity and watery mucus to allow sperm passage. External os opens slightly and fills with mucus.
Luteal phase as progesterone increase, the mucus thickens and reduced elasticity.

30
Q

How do oral contraceptive pills work?

A

O + P: High levels inhibit ovulation, keep cervical mucus thick, make endometrium less receptive, and change how cilia beat.

P only: Similar but doesnt inhibit ovulation.

31
Q

How does polycystic ovarian syndrome occur? What are the symptoms?

A

LH and FSH is out of balance as there is no negative feedback, so there is continuous O production.
Diagnosed when LH:FSH is >2:1.
Symptoms: no ovulation, lack of menses, weight gain, acne.

32
Q

What is spermatogenesis?

A

Process by which immature stem cells (spermatogonia) proliferate and differentiate into mature sperm.

33
Q

How long is the process of sperm maturation?

A

64 days but is a continual process.

34
Q

Name the 3 phases of spermatogenesis.

A
  1. Proliferative phase.
  2. Meiosis.
  3. Spermatogenesis.
35
Q

Outline the proliferative stage of spermatogenesis?

A

3 types of stem cell, A dark, A pale and B.
A dark are a back up incase there is severe damage to spermatogenesis.
All proliferative phases take place on the BM.

A dark A pale -> B -> Meiosis.

36
Q

Outline the meiosis stage of spermatogenesis?

A

Meiosis creates a resting spermatocyte (diploid 2n). 1st meiotic division produces a secondary spermatocyte.
2nd meiotic division produces 2 round spermocytes (haploid n).

Before a secondary spermacyte is produced (leptonene stage), cells move off the BM through the blood-testes barrier (to protect haploid cells from the bodys immune system).

37
Q

Outline spermatogenesis (3rd stage).

A

Round spermatid becomes an elongated spermatid via cell differentiation.
Nuclear condensation to stop DNA activity.
Golgi apparatus forms the acrosome.
Centriole forms the tail.
Cytoplasm redistributes and a droplet buds off as the residual body is lost.
Mitochondria rearrange in middle piece.

38
Q

Describe the structure of a spermatozoa?

A

Head: Nucleus which compacted and inactive DNA. Surrounded by the acrosome which has enzymes for penetrating the egg.

Midpiece:: Contains many mitochondria for generating power.

Tail: Generates movement.

39
Q

What is the role of FSH in males?

A

Stimulates sertoli cells - so stimulates spermatogonial proliferation and differentiation.

40
Q

What is the role of LH in males?

A

Stimulates leydig cells to secrete testosterone.

41
Q

What is the role of testosterone in males?

A

Stimulates sertoli cells and peritubular myoid cells.
Critical for passage of spermocytes through meiosis as it stimulates spermatogenesis.
Also secreted in the blood to maintain androgen-dependent structures e.g. prostate, and stimulates sex drive.

42
Q

List the proliferation of spermatogonia and what hormone acts for proliferation?

A 
Spermatogonia: FSH
Primary Spermatocyte: FSH & LH
Secondary Spermatocyte: T
Spermatids: T
Spermatozoa: T
43
Q

What is the role of the epidiymis in sperm maturation?

A

Non-motile and non-fertile enter at the head and become motile and fertile as they travel down to the tail.
The tail acts as a sperm storage area.

44
Q

What is an endocrine disruptor?

A

Exogenous chemicals which disrupt normal endocrine function.

45
Q

How do endocrine disruptors work? What is the effect?

A
  1. Mimic hormones biological activity by binding to receptor and activating it (agonist). Causes too much hormone or hormone activity at an inappropriate time.
  2. Binds to receptor and prevents binding of the hormone (antagonist). Prevents normal hormone action.
  3. Interferes with metabolic processes. Affects synthesis or breakdown of hormones.
46
Q

What is a phthalate?

A

Man-made chemicals to increase flexibility of polyvinyl chloride plastics. E.g. dialysis tubing, coatings on tablets, cosmetics.

47
Q

What happened to rats exposed to phthalates in utero?

A

Abnormal testes development
Decreased germ cell numbers
Cryptorchidism, infertility, hypospadias, cancer.

48
Q

What is Diethystilbestrol (DES)?

A

Synthetic oestrogen prescribed to pregnant women in the past. Thought to stop spontaneous abortion and promote fetal growth.
Actually affected reproductive development, caused vaginal cancer and only noticed when children reached puberty.

Reproduction (5 decks)

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