Fig. 4
From: Ontogenetic characterization of sporangium and spore of Huperzia serrata: an anti-aging disease fern
Development of spores. a Primary wall cells (PAC) and sporogenous cells (SC); b primary sporogenous cells (PSC); c mitosis (MT) of primary sporogenous cell; d secondary sporogenous cells (SSC); e mitosis (MT) of a secondary sporogenous cell; f spore mother cells (SMC); g tetrahedral spore tetrads (TST); h bilateral spore tetrads (BST); i spore tetrads (ST); j vacuolated spores (VS); k immature spores (IM); l mature spores (MS); m abortive spore tetrads (AST)