精蟲能承受較鹼性環境，pH低於6.8精蟲無法存活

精液滲透壓(340–380 mOsm)高於血清滲透壓(280-300 mOsm)
精液pH7.2-8.0，精蟲能承受較鹼性環境，可在pH8-9間存活，但pH<6.8精蟲無法存活
精蟲細胞核包覆囊狀結構membrane bound (‘nuclear vacuoles’, more correctly ‘nuclear spaces’)---精蟲品質不佳
健康男性每日可製造數千萬~一億隻精蟲

http://humupd.oxfordjournals.org/content/19/suppl_1/i1.full

Figure 2

Fine structure of the human spermatozoon. Longitudinal sections through the sperm head parallel (A) and perpendicular (B) to the axis of the proximal centriole. Cutaway drawings show the organization of the midpiece (C) and principal piece (D) regions of the sperm tail. Reprinted with permission from Mortimer (1994), adapted from Pedersen and Fawcett (1976).