Are Sperm Alive?

Ed Arias earias1 at uic.edu
Sun Jan 12 01:32:03 EST 1997


Should I or shouldn't I...since my doctoral qualifying exams, I'm kinda leery about 
going up against professors...but I guess that's what they're always prodding us to 
do...I suspect you attempting to answer a layman's questions...but you should be 
accurate in your choice of words.

Dennis Goode wrote:
> 
> Sid Lipkin wrote:
> >
> > Always wondered this...Is human sperm classed as a living creature?
> >   Is there a genus of animals that it belongs to?  Can sperm survive
> >   outside the human body(in a lab setting)?
> >
> >    What about anti-bodies?  are they Alive in the sense that we define life?
> >      They have a purpose and act according to certain criteria?  is this life?
> >
> >   Sorry if this is uneducated...just curious
> 
> Sid,
> 
> In addition to the other answers to your interesting questions, I might add that
> human sperm are one of the stages in the life cycle of humans.

Dr. Goode, I am compelled to disagree with you.  As far as I know, sperm are incapable 
of any type of reproduction on their own, pathenogenic or any other.  If you have read 
or performed these experiments yourself, please cite the reference.  I have read of eggs 
undergoing parthenogenic activation...but not sperm.

Mammalian spern DO undergo various stages in their "life-cycle" 
(aka...spermogenesis)...but this does not include human beings unless they meet up with 
an egg.

> Like other
> multicellular organisms, we evolved from a single-celled organism,
> but have kept the unicellular stages of our life cycle as the sperm
> and the egg.

Can you tell me what type of eukaryotic organism does not develop (completely) from a 
unicellular "beginning"?  

> Both of these are highly differentiated single cells,
> and as such are definitely alive, eventhough sperm neither grow nor
> reproduce on their own, two of the defining properties of life.

Agreed.

> However they definitly show metabolism and response to stimili
> (chemotaxis toward  chemicals from the egg, and afertilization
> response upon contact with the egg).

This is the part of your response that really attracted my attention.  Could you tell me 
what molecule or chemical or stimulus (the easy answer) attracts sperm to the egg.  I 
work in mammalian reproduction...perhaps you work in a different system such as slime 
molds...somewhere I heard that cAMP may serve as a chemoattractant...but I've never 
heard of mammalian sperm following some chemoattractant from mammalian ova.  I'm 
currently writting my thesis...a reference in this "ova chemoattraction" would be 
beneficial (preferrably mammalian).

I grant you that you're "fertilization" response due to contact with the egg 
happens..although this is poorly understood (at least by more than one lab).  Patricia 
Saling from Duke and Gregory Kopf at Penn have led the work in the signal transduction 
events in mice upon sperm-zona binding that leads to the acrosome reaction.

> Basically Cell Biologists
> consider anything that is a cell to be alive, so sperm are alive but
> antibodies, proteins secreted from cells are not.
> 
> But then we do have to distinguish between an egg or sperm and a human
> "being",  and of course there is a big debate about when that
> beingness comes into existence.

A human "being" is created when upon the resumption of meiosis, the haploid chromosome 
from sperm and egg are joined to form the complete human chromosomal complement.  Like 
you say, "beingness" is a social question that I doubt will ever be answered by 
scientists...but rather by the current opinion.

> 
> To extend your question, which came first, the egg or the sperm ?
> The answer appears to be the sperm!
> Evidence is accumulating that we (the animals) evolved from
> unicellular Choanoflagellates that look and swim very much like
> animal sperm.  We (the multicellular form) seem to be an addition on
> the the life cycle of these seemingly simple organisms.

As I deluded to above...sperm are only half "an organism" and cannot reproduce on their 
own...as I'm sure you know.  As far as I small mind remembers...all types of mammalian 
sperm are flagellated...whether they resemble some Choanoflagellate or a giardia or some 
some sexually transmitted disease vector...that doesn't say much.  People say I look 
like Eric Estrada...that doesn't make me related.

In summary, sperm are only alive as long as they ARE alive...which is about 48-72 hours 
within the female reproductive tract.  Longer than a mayfly is alive...but thats about 
it.

> 
> -Keep asking questions; that's the best way to learn.
> 
> -Dennis
> Dr. M. Dennis Goode                 Phone (301) 405-6917
> Department of Zoology               Fax   (301) 314-9358
> University of Maryland              e-mail goode at zool.umd.edu
> College Park MD 20742
> *************************************************************
> "If the Lord Almighty had consulted me before embarking upon the
> creation, I should have recommended something simpler."
>             -Alphonso X of Castile, 15th Century

-- 
Ed Arias
University of Illinois at Chicago
Dept of Physiology & Biophysics
835 S. Wolcott Avenue
Chicago, IL  60612
Tel:    312.996.4161
Fax:    312.996.1414
e-mail: earias1 at uic.edu
WWW:    http://www.uic.edu/~earias1/



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