几种哺乳动物精子顶体膜囊泡形成的研究
Formation of acrosome membrane vesicles in mammalian spermatozoa
时期Ⅱ，精子细胞顶体囊泡扁平，细胞核延长，染色质浓缩成短丝状的染色质纤维；
Stage ⅱ, the spermatid acrosomal vesicle flattened and chromatin condensed into fibers like short filaments and the nucleus prolonged ;
精子囊