(1) Spermatogenesis in the charophyte Nitella has been followed in antheridia prepared for light and electron microscopy.
(2) A decrease in mucilage concentration is also observed in the young antheridia after 3 days of continuous darkness.
(3) Treatment of Nitella antheridia with colchicine results in various sperm abnormalities, depending upon duration of exposure and subsequent recovery.
(4) The formation of oogonia, antheridia, and oospores also occurred.
(5) Sperm released from antheridia treated for 24 hr and allowed to recover for 4-5 days possess branched flagella.
(6) A calcium chelator (EGTA), an ionophore (chlortetracycline), and inhibitors of the calcium-binding protein calmodulin (dibucaine, trifluoperazine, chlorpromazine) disrupted several discrete developmental steps associated with oosporogenesis: induction of antheridia, gametangial fusion, meiosis, oospore wall formation, and subsequent spore maturation.
(7) These substances may also be used up in the young antheridia during the lack of energy supply.
(8) In young antheridia, the structure of capitular cells is typical of meristematic cells.
(9) Differentiating gemma cells show localized protoplasmic accumulations of Ca2+ at sites where asymmetric cell divisions initiate the formation of rhizoids, antheridia or vegetative cells.
(10) In addition, poly(A)+ RNA was prepared from 7-day-old gametophytes of A. phyllitidis, induced to differentiate antheridia under generative conditions.