Mice and sexually dimorphic spleen size

[Ramona1885]

I am currently studying mice anatomy and helping to tutor other students. I find many places that say that male have a 50% larger spleen than females, however I cannot find any books or internet searches that explain this. Does anyone know the answer or have any theories on why males have larger spleens? Thank you!

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[VetMed812]

Who says this? I have not seen this in practice and I've necropsied thousands of mice. The spleen is a secondary lymphoid organ so not sure why there'd be a size difference even including the sex steroid induced differences. Typically these differences result in predilections to certain types of responses. There might be a reason you can't find scientific evidence to support this claim. I'd be curious to see sources especially if proven otherwise

 

[Ramona1885]

Sources I have include: Laboratory Mouse Procedural Techniques By John Bogdanske, and Exotic Animal Medicine for the Veterinary Technician by Bonnie Ballard

 

[VetMed812]

The data I have on mouse spleens does not appear to be significant based on sex but i haven't run any stats on them either... Genotype and body weight as well as infection/ disease status have an obvious effect. I don't have access to these texts and cannot look up what they say at least without requesting the books which would take about a week. Why do you think this is true? A google search was useless in convincing me either way.

 

[Ramona1885]

These are books that the students I am tutoring have been assigned to work out of. They do not give an explaination as to why males have larger spleens so I am looking for help with the answer. Both of these books were actually readable online. When I googled and wrote "Male mouse spleen 50% larger", I could turn to the pages I am referring to, but its no help. If I were to make a guess? Maybe since the spleen has to do with the immune system, it is bigger in males because they are more apt to fight eachother. I'm really not sure. I was hoping someone here could enlighten me.

 

[VetMed812]

These are books that the students I am tutoring have been assigned to work out of. They do not give an explaination as to why males have larger spleens so I am looking for help with the answer. Both of these books were actually readable online. When I googled and wrote "Male mouse spleen 50% larger", I could turn to the pages I am referring to, but its no help. If I were to make a guess? Maybe since the spleen has to do with the immune system, it is bigger in males because they are more apt to fight eachother. I'm really not sure. I was hoping someone here could enlighten me.

Actually that's not a bad guess. I could buy that explanation. It'd be a response due to fighting not in anticipation of fighting. There have been reports of increased lymph node size due to fighting as there's immune infiltrates and draining so I wouldn't see it as much of a stretch to say the response could become systemic if long term enough. Typically we separate mice due to fighting so maybe that's why I've never seen it. Hmm post an answer if you ever get one! I'm intrigued but not enough to find one on my own haha

 

[WhtsThFrequency]

Well....even by 16-20 weeks of age, male mice are typically 25-50% bigger than females (B6 background as reference) overall. Mice on a Balb/c background show even more of a difference in terms of body weight. Not surprising the larger mice have larger spleens.

I've personally never heard of there being a significant/documented difference based soley on sex, and I'm pretty decently versed in lab animal pathology.