You know the story of mammalian fertilisation : meg of sperm enter the vagina , only one fertilize the egg , more than one messes up the fertilized egg , yadda yadda yadda . turn out that ’s not the only way it can solve .
Birds , for example , always have multiple spermatozoan click each egg . Only one of those sperm really fertilizes the ovum , but the rest hang around inside the testicle ’s cytol . This quirk of Bronx cheer biota was first maintain in 1904 , but no one knows what they ’re doing in there .
A field of study in thelatest Proceedings of the Royal Society Bhas taken some baby steps toward understanding their function . Nicola Hemmings and Tim Birkhead from the University of Sheffield artificially inseminated zebra finch and chickens with abject numbers of spermatozoan and compare the result to either ( in the case of zebra finch ) natural copulations or ( in the font of wimp ) hokey insemination with large numbers of sperm .
They come up that if bird ova are n’t penetrated by multiple sperm cell , they wo n’t originate into chicks . No one knows exactly why embryonal development in birds needs the redundant spermatozoan . It may be related to the size of the shuttle egg : sperm carry protein that aerate embryologic development , but experiments with Japanese quail suggest that their ballock demand more of those protein than a single sperm can carry .
Hemmings and Birkhead also find that a larger proportion of sperm than expected made it to the orchis in the low - spermatozoan experiments , suggesting that the mother bird is somehow controlling how many sperm survive the stumble through their oviducts .
[ Hemmings and Birkhead 2015|NY Times ]
Image by The TerraMar Project viaFlickr|CC BY 2.0
get through the author at[email protect ] .
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