Studies on the Developmental Pattern of Pig Liver during Neonatal Period

Abstract

The aim of this study was to explore the develompental pattern of liver during neonatal period.Fifteen neonatal pigs were killed and sampled on newborn(day 0),day 3 and day 7 after birth,respectively.A portion of liver tissue was taken for transmission electron microscopic examination.Such biochemical indices as DNA,RNA and liver glycogen were analyzed according to appropriate methods.The hepatocyte cords were arranged in a radial mode and there were abundant mature cellular organelles such as mitochondria and rough endoplasmic reticula in the liver of neonatal pigs.Liver weight increased at a higher rate than body weight in the first 7 days,especially in the first 3 days after birth.Similarly,liver protein content increased significantly in the first postnatal week(P<0.01).In contrast,liver glycogen content was highest at birth and decreased markedly after birth(P<0.01).DNA concentration was lowest(P<0.05) and RNA concentration highest (P<0.05) in the liver of 3-day old piglets.In conclusion,the hepatocytes of piglets had already developed both in structure and in function at birth.Both the size and the number of hepatocytes increased greatly,and therefore liver grows quickly during the short period after birth.

選擇新生仔豬15頭,分別于出生當日(0 d)、出生后3 d及7 d屠宰取樣,制作肝臟電鏡切片進行組織學分析,并測定肝臟中DNA、RNA含量及常規生化指標。結果顯示:新生仔豬肝細胞中內質網、線粒體等細胞器都很豐富,而且各細胞器的結構已經發育成熟。肝臟質量在仔豬出生后1周尤其是 3 d內迅速增加(P<0. 01),遠遠快于體重增加的速度。仔豬肝臟的蛋白質含量在生后1周也迅速增加(P<0 .01);而肝糖原貯備在剛出生時較高,出生后迅速下降(P<0 .01)。仔豬出生后肝臟中DNA和RNA濃度的變化趨勢正好相反,前者在出生后 3 d內明顯下降(P<0. 05),4~7 d又有增加趨勢,而RNA濃度以3 d為最高。試驗結果表明,仔豬到出生時肝細胞的結構和功能基本發育成熟。仔豬出生以后,肝臟的生長發育十分迅速,不僅肝細胞的數量快速增加,肝細胞的體積也不斷增大。