female:male ratio in K-3 kids

Joy Frestedt frest001 at MAROON.TC.UMN.EDU
Mon Jan 15 03:42:08 EST 1996

Not sure if this was mentioned yet, but "male" (carrying the Y chromosome) 
sperm cells can travel faster than "female" (carrying the x chromosome 
which is much bigger than the Y) sperm cells due to the smaller amount of 
genetic material in the "male" sperm head!


On Sun, 14 Jan 1996 23:02:22 -0800, 
Kimberly Anne Chapman  <kchapman at paul.spu.edu> wrote:

>On 11 Jan 1996, Jane Dorweiler wrote:
>> Whether this phenomenon is widespread or not, the first thing that came to mind 
>> when I heard this was the fact that it was about 6 years ago or so that I 
>> started to hear theories on how to increase the likelihood of conceiving a child
>> of a particular sex by controlling the frequency and/or timing of intercourse 
>> relative to ovulation.  Perhaps there just happened to be many couples who were 
>> trying for a particular sex child based on these methods??
>> Jane Dorweiler                 **  Regardless of what they say about the 
>> Department of Plant Biology    **  cat, curiosity is a good thing.  It's 
>> University of Minnesota        **  what makes each and every one of us
>> dorwe001 at maroon.tc.umn.edu     **  a scientist!!
>I'd like to have more faith in American couples and discount the 
>possibility of people trying for a child of a particular sex.  That has 
>some very ugly ramifications.  But I think Jane Dorweiler is definitely 
>onto something regarding the frequency and time of intercourse.  We are 
>all aware of the significant changes in a woman's body throughout the 
>menstrual cycle.  In a genetics course I was reminded that one of these 
>changes was the fluctuation of the pH of the vagina.  I was amazed to 
>hear that studies have been done showing that some spermatozoa have a 
>higher affinity and functioning capacity in a slightly more acidic 
>environment while others do better in a more basic environment.  
>Unfortunately I'm unable to recall which sperm cells are which, but I'll 
>be contacting the prof who taught the course.  In light of this 
>information, I would hypothesize that the timing of intercourse in 
>conjunction with the current pH of the vagina is what influences which 
>sperm cells live to reach the ovum, therefore having a higher probability 
>to fertilize it.
>        I'd be very interested in feedback.  Thanks in advance!!

Joy L. Frestedt 
Laboratory Medicine and Pathology
University of Minnesota

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