Dunn B E, Fitzharris T P
J Exp Zool Suppl. 1987;1:75-9.
The chorionic epithelium of the developing chick embryo consists of two major cell types, villus cavity (VC) and sinus-covering (SC) cells. Ultrastructurally, VC cells contain apical microvilli with numerous underlying vesicles, whereas SC cells possess thin cytoplasmic processes (containing occasional vesicles) overlying adjacent blood sinuses. This study was performed to determine whether vesicles observed in VC and SC cells are endocytic in nature and whether endocytosis is limited to either VC or SC cells. Exposure of air space chorionic epithelium in ovo to microperoxidase (MRP-11) resulted in endocytic uptake of marker by the thin cytoplasmic processes of 70% of SC cells. Vesicles containing MRP-11 reaction product were also observed in approximately 20% of VC cells. Exposure of the chorionic epithelium of shell-less cultured embryos to horseradish peroxidase (HRP) resulted in endocytic uptake of HRP in approximately 80% of SC cells and in 33% of VC cells. Thus, VC and SC cells demonstrate endocytic activity both in ovo and in shell-less culture. In ovo, endocytosis may be involved in the recovery of water and/or ions from the eggshell or shell membranes.
发育中的鸡胚绒毛膜上皮由两种主要细胞类型组成，即绒毛腔（VC）细胞和窦覆盖（SC）细胞。在超微结构上，VC细胞含有顶端微绒毛，其下方有大量小泡，而SC细胞在相邻血窦上方具有薄的细胞质突起（偶尔含有小泡）。进行这项研究是为了确定在VC和SC细胞中观察到的小泡在本质上是否是内吞性的，以及内吞作用是否仅限于VC或SC细胞。将卵内气室绒毛膜上皮暴露于微过氧化物酶（MRP-11）中，导致70%的SC细胞的薄细胞质突起内吞标记物。在大约20%的VC细胞中也观察到含有MRP-11反应产物的小泡。将无壳培养胚胎的绒毛膜上皮暴露于辣根过氧化物酶（HRP）中，导致大约80%的SC细胞和33%的VC细胞内吞HRP。因此，VC和SC细胞在卵内和无壳培养中均表现出内吞活性。在卵内，内吞作用可能参与从蛋壳或壳膜中回收水和/或离子。
