The male reproductive system
In this simulation, the effects of various treatments on male reproductive function will be investigated. Parameters to be studied include testicular, endocrine and exocrine function, sperm viability and accessory organ function.
During this simulation, you should:
- Familiarise yourself with the general structure of the male reproductive tract.
- Identify the parts of the system that contain spermatozoa.
- Determine where the spermatozoa become capable of motility during their passage along the reproductive tract.
- Relate the state of each organ back to testosterone and its role in maintaining male reproductive function via the hypothalamic pituitary gonadal (HPG) axis.
- Determine the hormonal regulation of male sex accessory organs including the prostate and seminal vesicles.
Description of treatments applied in this simulation
- Gonadectomy - A standard procedure used to observe the effects on male secondary sex tissues of removal of male hormones (androgens). This involves surgical removal of the testes, epididymis and part of the vas deferens.
- Cryptorchid - Surgical procedure to physically re-locate the testes into the abdomen and demonstrate the importance of changing body temperature on sperm production.
- Bilateral (open-ended) vasectomy - When a surgical incision is made in the vas deferens, the path of sperm from the testes to the external genitalia is removed. Vasectomy is commonly used in men as a safe and effective contraceptive method, without altering the male hormonal levels.
Hormonal or pharmacological manipulation
- Treatment of Rats with EDS - Ethane dimethane sulphonate (EDS) is a chemical that interferes with steroid production in Leydig cells.
- Treatment of Rats with Excess Androgen - Testosterone propionate is a steroid. It will supply excess levels of systemic androgens to the male rat.
- Treatment of Rats with excess Estradiol - Estradiol benzoate is a steroid that will supply excess levels of systemic estrogen to the male rat.
- Treatment of Rats with GnRH antagonist - Clinical trials are presently being performed on the effectiveness of treatment of males with this GnRH antagonist as a male contraceptive pill because of its effects on the HPG axis.
These treatments on plasma testosterone, as well as the male reproductive organs will be investigated by comparison with data obtained in control rats.
Statement on animal experiments
Much of what we know about the body comes from experiments using whole animals, including humans, or tissues taken from (dead) animals. Progress in physiology depends on further experimentation.
In asserting the importance of continued experimentation, physiologists are well aware of the obligation of all biologists to ensure that the experiments undertaken are demonstrably necessary and that experimental animals are properly looked after and treated humanely at all times.
The National Health and Medical Research Council (NH&MRC) of Australia, and more recently the CSIRO and the Australian Agricultural Council, have played a prominent part in setting up standards for the care and use of experimental animals in Australia. Biological research groups such as the Australian Physiological and Pharmacological Society have for some time accepted these standards, embodied in a Code of Practice for the Care and Use of Animals for Experimental Purposes, as guiding principles. The ‘General Principles for the Care and Use of Animals for Scientific Purposes' from the 2004 Code are set out in full in the unit guide.
This simulation adheres with the principles of these guidelines by reducing unnecessary use of animals. Whilst the dissection of the control rat is a necessary part of the practical, we have refined the experimental approach and used the data collected over the past 5 years in this simulation.