Lecture 4.1: Hormonal Control of Reproduction Flashcards
Hypothalamic-Pituitary-Gonadal Axis: Males
Hypothalamus (GnRH)
Anterior Pituitary (FSH & LH)
Gonads/Testes (Inhibin, Testosterone)
What cells in males does FSH affect? What do these produce?
Sertoli Cells produce Inhibin
What cells in males does LH affect? What do these produce?
Leydig Cells produce Testosterone
Hypothalamic-Pituitary-Gonadal Axis: Females
Hypothalamus (GnRH)
Anterior Pituitary (FSH & LH)
Gonads/Ovaries (Inhibin, Progesterone, Oestrogen)
What cells in females does LH affect? What do these produce?
Theca Cells produce Androgens
What cells in females does FSH affect? What do these produce?
Granulosa Cells produce Inhibin, Progesterone, Oestrogen
What are the 2 parts of the Pituitary Gland?
- Anterior Pituitary
- Posterior Pituitary
What is the composition of the Anterior Pituitary Gland?
- Arises from Rathke’s Pouch
- Not nervous tissue
- Endocrine gland
- Mostly ‘trophic’ hormones
What is the composition of the Posterior Pituitary Gland?
- Nervous tissue
- Neurosecretory gland
What does the Posterior Pituitary secrete? (2)
- ADH
- Oxytocin
What is the importance of Oxytocin in reproduction? (4)
- Social interaction
- Orgasm
- Labour
- Lactation
Glycoprotein Hormones ()
- Follicle stimulating hormone
- Luteinising hormone
What Cells produce FSH and LH?
Gonadotrophic Cells of Anterior Pituitary
Polypeptide Hormones
- Growth Hormone
- Prolactin
What Cells produce GH?
Somatotrophs
What Cells produce Prolactin?
Lactotrophs
Anterior pituitary secretions are controlled by the….via….travelling in the …….?
- hypothalamus
- hormones
- hypophyseal portal circulation
What Hypothalamic hormone controls reproductive
hormones? How often is it released?
- Gonadotrophin releasing hormone (GnRH)
- Release is pulsatile (about once an hour)
What is Control of GnRH secretion influenced by?
- Other neurones
- KISS 1 neuron is a key player
- Environmental effects
- Body weight
- Influence KISS1 neurone or GnRH neurones directly
- ‘Feedback’ from gonadal hormones
What male hormone reduces GnRH secretion?
Testosterone
….. titres of oestrogen reduce GnRH secretion?
Moderate
…..titres of oestrogen alone promote GnRH secretion?
High
What hormone prevents positive feedback of high oestrogen?
Progesterone
What is the difference between how oestrogen and progesterone reduce GnRH?
- Oestrogen reduces GnRH per pulse
- Progesterone frequency of pulses
What hormone from the gonads inhibits FSH secretion selectively?
Inhibin
What does FSH bind to in the Testis?
Sertoli Cells
What effect does FSH have in the testis?
- Stimulates spermatogenesis
- Focus on meiotic steps
- Sertoli cells stimulated to produce Inhibin
- Inhibin secretion is a marker of the rate of
spermatogenesis
Actions of Testosterone (6)
- Stimulates gamete production
- Maintains epididymis and vas deferens
- Maintains prostate, seminal vesicles, bulbo-urethral
glands - Production of semen
- Development and maintenance of external genitalia
and secondary sexual characteristics - Sexual dimorphism throughout the body & behaviour
Female Reproductive Cycle: ‘Follicular’ or ‘Proliferative’ Phase
- Previous cycle has been unsuccessful so starts again
- Follicles grow in ovary
- Uterus prepared for sperm transport & implantation
of conceptus - Changes to facilitate sexual interactions
Female Reproductive Cycle: Ovulation
- Brief period of fertility
- Formation of corpus luteum
Female Reproductive Cycle: ‘Luteal’ or ‘Secretory’ Phase
- Corpus luteum in ovary grows and secretes more
steroids [(oestrogen (from granulosal luteal cells),
progesterone (from thecal luteal cells)] - Changes in uterus in preparation for pregnancy
- Starts to decrease in size after 7-10 days
- Autophagy due to hypoxia/starvation
- Lack of maintenance signals from embryo
- CL dies after 14 days
What do Oestrogens stimulate? (7)
- Fallopian tube function
- Thickening of endometrium
- Growth & motility of myometrium
- Thin alkaline cervical mucus
- Vaginal changes
- Changes in skin, hair, metabolism
- Calcium metabolism
Progesterone Actions (7)
- Further thickening of endometrium into secretory
form - Thickening of myometrium, but reduction of motility
- Thick, acidic cervical mucus
- Changes in mammary tissue
- Increased body temperature
- Metabolic changes
- Electrolyte changes
Changes in the Uterus in Menstrual Cycle: Early Proliferative
Glands sparse
Straight
Changes in the Uterus in Menstrual Cycle: Late Proliferative
Functionalis has doubled
Glands now coiled
Changes in the Uterus in Menstrual Cycle: Early Secretory
Endometrium maximum thickness
Very pronounced coiled glands
Changes in the Uterus in Menstrual Cycle: Late Secretory
Glands adopt characteristic “saw-tooth” appearance
