stratum use层级使用stratumn.地层；阶层stratum structure method地层结构法stratum reticulare corii真皮网状层stratum pigmenti retinae色素层, 视网膜色素层stratum griseum centrale(拉)中央灰(质)层stratum granulosum ovarii泡状卵泡粒层, 卵巢滤泡粒层stratum bacillare retinae视网膜杆体层Stratum opticum of retina视网膜视层stratum of private owners私营业主阶层stratum griseum profundum(拉)深灰(质)层stratum cerebrale retinae视网膜神经层