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Sequence of ejaculation affects the spermatozoon as a carrier and its message
1Assisted Conception Unit, Birmingham Women's Hospital and Reproductive Biology and Genetics Group, University of Birmingham, Metchley Park Road, Birmingham B15 2TG, UK. L.Bjorndahl@bham.ac.uk
Reproductive Biomedicine Online
|December 6, 2003
Summary
Human ejaculation is not a uniform fluid; sperm are expelled with zinc-rich prostatic fluid first. Laboratory conditions create unphysiological environments for sperm, impacting research and assisted reproduction.
Area of Science:
- Reproductive Biology
- Sperm Physiology
- Assisted Reproduction Technologies
Background:
- Common misconception of seminal fluid as a homogeneous medium for spermatozoa.
- Spermatozoa are expelled in initial fractions, mixed with zinc-rich prostatic fluid.
- Natural exposure involves cervical mucus, protecting sperm from later hostile fractions.
Purpose of the Study:
- To challenge the notion of homogeneous seminal fluid.
- To highlight the environmental challenges faced by spermatozoa in laboratory settings.
- To discuss implications for sperm research and assisted reproduction.
Main Methods:
- Analysis of seminal fluid composition and ejaculation fractions.
- Comparison of natural sperm environments with laboratory conditions.
- Review of existing literature on sperm physiology and cryopreservation.
Main Results:
- Spermatozoa are primarily expelled with zinc-rich prostatic fluid in early fractions.
- Laboratory conditions (light, oxygen, CO2, pH, osmolarity, zinc/calcium bioavailability) are unphysiological.
- Seminal plasma in vitro differs significantly from the in vivo environment.
Conclusions:
- The composition and environment of seminal plasma are heterogeneous.
- Laboratory handling of spermatozoa introduces significant physiological stress.
- Unphysiological conditions may impact the outcomes of assisted reproduction and sperm research.