ARE, CELL, CELLULAR, CLEARLY, CRYOFIXATION, CRYOFIXED, DENSELY-PACKED, DON, E, E-FACE, ECTOPLASMIC, ELECTRON, FACE, FAWCETT, FRACTURE, FRACTURED, FREEZE, FREEZE-FRACTURE, FREEZE-FRACTURED, FROM, GUINEA, HISTOLOGY, IMAGING, MEDICAL, MICROGRAPH, MICROGRAPHY, MICROSCOPY, NUCLEAR, NUCLEUS, OF, P-FACE, PIG, PORE, PORES, PROTOPLASMIC, SCIENCE, SPERMATID, TEM, TESTIS, THE, TRANSMISSION, VISIBLE,