EN
We consider the discrete survival red blood cells model
(*) $N_{n+1} - Nₙ = -δₙNₙ + Pₙe^{-aN_{n-k}}$,
where δₙ and Pₙ are positive sequences. In the autonomous case we show that (*) has a unique positive steady state N*, we establish some sufficient conditions for oscillation of all positive solutions about N*, and when k = 1 we give a sufficient condition for N* to be globally asymptotically stable. In the nonatonomous case, assuming that there exists a positive solution {Nₙ*}, we present necessary and sufficient conditions for oscillation of all positive solutions of (*) about {Nₙ*}. Our results can be considered as discrete analogues of the recent results by Saker and Agarwal [12] and solve an open problem posed by Kocic and Ladas [8].