PHY3181 Lecture Notes - Squamous Metaplasia, Glucocorticoid, Hypothalamus
4 Jun 2018
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Week 2. Male Reproduction II and Male Reproductive
Endocrinology
MALE REPRODUCTION II
• Two main functions of the testis:
1. Spermatogenesis/sperm production
Seminiferous tubules
Sertoli cells
Germ cells
2. Hormone synthesis and secretion
Interstitium
• Interstitial tissue:
o Leydig cells
Responsible for steroidogenesis
Have receptors for LH
2-way paracrine interactions with Sertoli cells
Often closely associated with the blood supply
o Highly vascular (only part of the testis that receives blood from the heart/arterial system
– where LH and FSH are coming from and how androgen gets back into the central
system)
o Well-developed lymphatics
o Loose oetie tissue sall aout, hy it’s spogey ad aophages
• Control of testicular steroidogenesis
o Estrogen particularly acts on the brain
o Cholesteol is the statig podut ad is itial to hae o else o’t e ale to podue
testosterone
o Cholesterol can either be taken up from blood/diet, made from acetate, or taken up
from stores (common to have large stores of cholesterol)
find more resources at oneclass.com
find more resources at oneclass.com
o Leydig cell:
cAMP is a message to produce androgens
testosterone -> aromatase -> oestradiol = main source of oestrogen
o Sertoli cell
5-α reductase reduces testosterone to DHT (taking away a H) which is important
to maintain secondary reproductive organs and is the most functional form of
androgen (3x as testosterone)
It is controversial that sertoli cells can also produce a small amount of oestrogen
o Two pathways starting with cholesterol and going through pregnenolone (intermediate)
o Direction of pathway depends on the state of the cell (just know that there are 2
possibilities)
o Enzymes in both pathways are exactly the same, only getting a different product
o If 3β-HSD is present then pregnenolone is taken directly to progesterone (pathway for
women)
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find more resources at oneclass.com
• For any steroid producing cell to produce steroids, it usually has to have smooth ER
-> tend to be large, stain up well because of huge wells around ER where transformations are
happening
• Relationship between LH and testosterone release from the leydig cells
o Strong linkage
o Pulse of LH = pulse of testosterone (just to the right)
• Structure of steroid hormones:
o Not constructed of aa like protein hormones
o Ring structure typical of all steroids:
o Hydrophobic (lipophilic)
o Do’t have receptors on membranes – can just pass through and find receptors inside
cell itself
o Synthesised by steroidogenic cells
o Synthesis via complex pathway with cholesterol as precursor
• Common steroid hormones:
o Androgens: testosterone and DHT which stimulates spermatogenesis, male sexual
function and behaviour
o Oestrogens: oestradiol and oestrone for female sexual function, behaviour (both sexes)
and bone
o Progestogens: progesterone for menstrual cycle and pregnancy
o Corticosteroids: glucocorticoids and mineralocorticoids for carbohydrate metabolism,
stress and blood pressure
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Male reproduction ii: two main functions of the testis, spermatogenesis/sperm production. Germ cells: hormone synthesis and secretion. Often closely associated with the blood supply: highly vascular (only part of the testis that receives blood from the heart/arterial system. 5- reductase reduces testosterone to dht (taking away a h) which is important to maintain secondary reproductive organs and is the most functional form of androgen (3x as testosterone) If 3 -hsd is present then pregnenolone is taken directly to progesterone (pathway for women: for any steroid producing cell to produce steroids, it usually has to have smooth er. Usually have reduced testicular function: male accessory sex glands: epididymis and vas deferens structure and function, collects sperm from testis, epididymis: Where sperm matures and has high motility. > sperm has high direct motility and membranes have changed so it can now interact with egg.
