Male Reproductive Endocrinology Flashcards
(33 cards)
What are the two compartments in the testes?
The seminiferous tubules and interstitium.
What cells are in the seminiferous tubules and interstitium?
Seminiferous tubules - serotoli cells
Interstitium- leydig cells
What are the three main cells that end up forming a sperm?
Spermatogonia
Spermatocytes
Spermatids
What are the two type of spermatogonia?
Types A and B
- type A is split into dark and pale forms
- Dark As divide to form one dark A and one pale A
- pale A mature into type B spermatogonia
- type B mature into primary spermatocytes
How do spermatocytes become spermatids?
Primary spermatocytes enter MEIOSIS I
This results in the production of secondary spermatocytes
These undergo MEIOSIS II to produce spermatids
How to spermatids become spermatozoa?
The differentiate (called spermiogenesis)
How does spermiogenesis occur?
Turns from round to elongate (no more cell divisions) Grows a tail for propulsion Midpiece forms - mitochondria Acrosome forms Cytoplasmic remodelling Nucleus compacts
What is the residual body and what happens to it?
It’s a bin for excess cytoplasm after spermiogenesis has happened, and it’s phagocytosed by SC
Describe the head, tail and midpiece of the sperm.
Head - is a nucleus with compacted and inactive DNA, surrounded by an across me containing enzymes to break into the egg
Midpiece - central filamentous core with many mitochondria
Tail - propels the sperm
What regulates spermatogenisis?
HPG axis
- hypothalamus releases GnRH
- GnRH stimulates the anterior pituitary to release FSH and LH
What is the action of FSH and LH?
FSH stimulates serotoli cells to increase spermatogenisis and inhibin production.
LH cells stimulate the leidig cells to produce more testosterone which also stimulates the serotoli cells
Testosterone and inhibin suppress the anterior pituitary
Inhibits suppresses GnRH release
What are the functions of testosterone?
Allow development and function of the male reproductive organs
Sustain secondary sex characteristics
Stimulate spermatogenesis
How long does it take to make a mature sperm?
64 days - begins at puberty, and ends at death
What are endocrine disruptors?
Exogenous substances that disrupt normal endocrine function
- can increase or decrease it
What can endocrine disruptors affect?
The endocrine organ itself Related tissues Hormone or receptor Human or animal Can be natural or man-made
Name some categories of endocrine disruptors
Natural hormones
Natural chemicals
Synthetically produced pharmaceuticals
Man-made chemicals
What are natural hormones, and give some examples.
They are hormones released into the environment
- e.g. Sewage slurry spread on fields
What are natural chemicals, and give some examples.
These are produced by plants or fungi
- e.g. Phosphoestrogen
Give some examples of synthetically produced pharmaceuticals.
Contraceptive pill
Treatments for hormone responsive cancers
Give some examples of man-made chemicals, (that are endocrine disruptors)
Some pesticides (DDT) Chemicals in some products (some plastic additives) Industrial chemicals (PCBs)
How do endocrine disruptors work? (3 different mechanisms)
1) mimic hormone biological activity by binding to a receptor and activating it (agonist)
- too much hormone activity at an inappropriate time
2) bind to a receptor to prevent binding of the natural hormone (antagonist)
- prevents normal hormone action
3) interferes with metabolic processes in the body
- affects synthesis or breakdown of natural hormones
What reproductive problems can endocrine disturbers cause?
Reduced fertility Menstrual problems Early puberty Brain/behavioural problems Cancers
What are phthalates?
Man-made chemicals that may be a risk to human development (especially male infants)
Where are phthalates found?
Dialysis tubing Solvents Insect repellents Building materials Car parts Cosmetics
