|
Temperature affects spermatogenesis: high temp., low sperm count used as contraceptive method (poor) -males encouraged to wear loose underwear if trying to conceive. Many other causes beyond scope of this course
Problems in Studies on Sperm Loss in Males
Evidence exists that there has been a decrease in quality of semen (# sperm/mL, motility of sperm) in last 50 years in males of industrialized countries--due to pollution?
But it is very possible that methods of assessing sperm numbers vary from lab to lab and with time and that many of reported changes in sperm counts due to various factors are not valid because of this Swan & Elkin (1999, BioEssays 21: 614-621) have reviewed the literature and conclude that although the older methods (i.e., sperm counting in a hemocytometer which was originally designed for counting blood cells) are "surprisingly reliable" in spite of a large random error.
Thus new more precise methods such as the use of flow cytometry should be used to find out if there is an actual decrease in the quality of human semen (e.g., Hacker-Klom et al, 1999. Human Reproduction 14: 2506-2512.
This information was provided by Professor Danton H. O'Day - Univerisity of Toronto at Mississauga - Canada. Unless otherwise stated the information and graphics that are presented within this embryology section are the sole property of Danton H. O'Day, copyright 1998(c), 1999(c), 2000(c), 2001(c), 2002(c).
|
Embryology 
