Observation of pacemaker cells,transitional cells,and interstitial tissue components in sinoatrial node of mice at different ages using four staining methods
MENG Jian
FAN Hongguang
Abstract：Objective To observe the quantitative changes of pacemaker cells(P cells)and transitional cells(T cells)as well as interstitial tissue components in sinoatrial nodes of mice at different ages using HE staining,modified Mas-son's trichrome staining,Verhöeff's elastic fiber staining,and picrosirius red staining.Methods Twenty male C57 wild-type mice were divided into four groups(n=5 each):neonatal group(10-day-old),young group(3-6 months),middle-aged group(10-15 months),and old group(18-24 months).After euthanasia,the hearts were harvested to prepare paraf-fin sections of the sinoatrial node.HE staining,modified Masson's trichrome staining,Verhöeff's elastic fiber staining,and picrosirius red staining were performed to evaluate P cell count,T cell count,P/T cell ratio,total cell density,and proportion of collagen fiber area;Verhöeff's elastic fiber staining was used to observe the the proportion of elastic fiber ar-ea.Results HE staining results:The P cell count decreased sequentially in the neonatal,young,middle-aged,and old groups,while the proportions of collagen fiber area increased(all P<0.05).The T cell count increased in the neonatal,young,and middle-aged groups,and the T cell count was lower in the old group than in the young and middle-aged groups(all P<0.05).The P/T cell ratio was higher in the neonatal and young groups than in the middle-aged and old groups,and the total cell density was lower in the old group than in the other groups(all P<0.05).Modified Masson's trichrome stain-ing results:The P cell count and P/T cell ratio decreased sequentially,while the proportions of collagen fiber area in-creased in the neonatal,young,middle-aged,and old groups(all P<0.05).The T cell count increased in the neonatal,young,and middle-aged groups but decreased in the old group in comparison with that of the middle-aged group(all P<0.05).The total cell density was lower in the old group than in the other groups(P<0.05).Verhöeff's elastic fiber stain-ing results:The P cell count decreased,while the elastic fiber and the proportions of collagen fiber area increased in the neonatal,young,middle-aged,and old groups(all P<0.05).The T cell count increased,whereas the P/T cell ratio de-creased in the neonatal,young,and middle-aged groups;the old group had a higher T cell count but a lower P/T cell ra-tio than the young group(both P<0.05).The total cell density was lower in the old group than in the other groups(all P<0.05).Picrosirius red staining results:Compared with the neonatal group,the middle-aged and old groups showed re-duced P cell counts and increased proportions of collagen fiber area,with more pronounced changes in the old group(all P<0.05).The young,middle-aged,and old groups had higher T cell counts than the neonatal group,and the middle-aged group had a higher count than the young group(all P<0.05).The P/T cell ratio was higher in the neonatal group than in the other groups,and the total cell density was lower in the old group than in the other groups(all P<0.05).Conclusion With aging,the P cell count in the sinoatrial node decreases,the T cell count first increases and then de-creases,and the collagen and elastic fibers in the interstitial tissues gradually increase,indicating interstitial remodeling.
Keywords：sinoatrial nodepacemaker cellstransitional cellscollagen fiberselastic fibersinterstitial tis-suessenescence
Publication Date：2025-06-25
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 23-28 )