摘要Parathyroid glands(PTG)are essential in maintaining mineral homeostasis,particularly in regulating blood calcium(Ca)and phosphorus(P)levels.The endocrine regulation via parathyroid hormone(PTH)is a prerequisite for the efficient utilization of dietary P.The PTG contain lobules of PTH-producing chief cells surrounded by extracellular collagen.It is hypothesized that the areal proportions of chief cells and extracellular collagen in PTG are dependent on dietary P intake.Based on PTG gene expression patterns,a total of 18 crossbred pigs balanced for sex and litter were fed one of three long-term diets with low(n=6),medium(n=6),or high P levels(n=6)from weaning at d 28 until slaughter at d 120.Total dietary P levels of low,medium,and high P groups were 5.20,6.48 and 7.80 g/kg diet for grower,respectively,and 4.12,5.50 and 6.96 g/kg diet for fattener,respectively.The effects of P supply were analyzed for their impact on the microscopic structure of porcine PTG using microphotographs following Azan trichrome staining verified by immunohistochemistry of PTH,calcium-sensing receptor(CaSR),collagen type Ⅰ(COL1),and collagen type Ⅲ(COL3)and related to gene expression data.His-tological stainings of PTG showed significantly reduced areas of PTG chief cells(P＜0.001)and increased extracellular collagen(P＜0.001)in animals fed low dietary P compared to control and high P diets.The long-term adaptation to a low P diet indicates a PTG reorganization and suggests that the lobular structure,along with the extracellular matrix,may play a role in the complex processes of mineral homeostasis.Mechanistically,this could be a component of a physiologic and possibly reversible response following long-term P intake,which has implications for PTG regulation and,consequently,PTH control.