Whyte A, Wooding F B, Saunders P T
Arch Anat Microsc Morphol Exp. 1986;75(2):91-109.
Tissue mechanically dissociated from blastocysts of the pig around the time of implantation were found to produce, in culture, free-floating multicellular spheroids (trophospheres) and adherent monolayer cells. Ultrastructurally the two cellular layers of the trophospheres were very similar to those of the blastocyst but the trophosphere outer layer characteristically contained very large mitochondria with a vastly expanded matrix and few cristae. Similar mitochondria were also found in the monolayer cells. Using a monoclonal antibody specific for pig trophectoderm, it was found that about 20% of the monolayer cells, and some of the spheroids expressed this trophectodermal antigen. In the latter case the antigen was present only on the surface facing the medium. The spheroids were fluid-filled and occasionally grew inside each other. The monolayer cells were predominantly uninuclear but did form a number of binucleate cells and in older cultures the occasional cell with many nuclei could be seen. The spheroids and the monolayer cells had similar glycoprotein profiles indicating that they were composed of similar cell populations. A glycoprotein of apparent molecular weight 68,000 observed in both spheres and monolayers may represent pig placental alkaline phosphatase. Both trophospheres and monolayer cells were observed to interconvert steroid precursors. It is apparent that the trophospheres share many features of the blastocyst and may thus represent a valuable model system similar to those described in other species for the investigation of their biochemical physiological and immunological properties.
在着床期前后从猪囊胚机械解离的组织，在培养中发现可产生自由漂浮的多细胞球体（滋养球体）和贴壁单层细胞。超微结构上，滋养球体的两层细胞与囊胚的两层细胞非常相似，但滋养球体的外层特征性地含有非常大的线粒体，其基质大大扩张，嵴很少。在单层细胞中也发现了类似的线粒体。使用针对猪滋养外胚层的单克隆抗体，发现约20%的单层细胞和一些球体表达这种滋养外胚层抗原。在后一种情况下，抗原仅存在于面向培养基的表面。球体充满液体，偶尔会相互生长。单层细胞主要是单核的，但确实形成了一些双核细胞，在较老的培养物中可以看到偶尔有许多核的细胞。球体和单层细胞具有相似的糖蛋白谱，表明它们由相似的细胞群体组成。在球体和单层细胞中均观察到的一种表观分子量为68,000的糖蛋白可能代表猪胎盘碱性磷酸酶。观察到滋养球体和单层细胞都能相互转化类固醇前体。显然，滋养球体具有囊胚的许多特征，因此可能代表一种有价值的模型系统，类似于其他物种中描述的用于研究其生化、生理和免疫特性的模型系统。
