Jochims K, Kaup F J, Drommer W, Pickel M
Institute of Pathology, School of Veterinary Medicine, Hanover, Germany.
Res Vet Sci. 1994 Jul;57(1):75-80. doi: 10.1016/0034-5288(94)90085-x.
The protein A-gold was used to examine the transport of colostral IgG from the lumen of the gut to the circulation in four newborn calves and one 24-hour-old calf. The absorptive enterocytes of the duodenum, jejunum and ileum were investigated five to 60 minutes after administering colostrum, and 24 hours after birth. In the newborn calves, an intracellular micropinocytotic transport of IgG molecules was dominant throughout the entire small intestine. The amount transported increased from the duodenum to the ileum. In addition, evidence of a selective, receptor-mediated transport of IgG during the first few hours of life was provided by the presence of bovine clathrin at the microvillous membrane of the duodenal and jejunal enterocytes, indicating the existence of specialised vesicles for transport, the so-called 'coated' vesicles. No sign of paracellular transport was detected. Intestinal closure was interpreted as a multifactorial event comprising the replacement of the fetal intestinal epithelial cells by more mature populations, the initial cessation of transport at the basal and lateral cell membrane of the absorptive enterocytes, and an increase in intracellular proteolytic activity by lysosomes.
用蛋白A-金来检测4头新生犊牛和1头24小时龄犊牛初乳中免疫球蛋白G（IgG）从肠腔到血液循环的转运情况。在给予初乳后5至60分钟以及出生后24小时，对十二指肠、空肠和回肠的吸收性肠上皮细胞进行研究。在新生犊牛中，IgG分子的细胞内微胞饮转运在整个小肠中占主导地位。转运量从十二指肠到回肠逐渐增加。此外，在十二指肠和空肠肠上皮细胞的微绒毛膜上存在牛网格蛋白，这表明在生命的最初几个小时内存在IgG的选择性、受体介导的转运，这意味着存在用于转运的特殊囊泡，即所谓的“被膜”囊泡。未检测到旁细胞转运的迹象。肠封闭被解释为一个多因素事件，包括胎儿肠上皮细胞被更成熟的细胞群体所取代、吸收性肠上皮细胞基底和侧细胞膜上转运的最初停止，以及溶酶体导致的细胞内蛋白水解活性增加。
