OCCURRENCE OF APOPTOSIS IN SEROSA OF PERIPLANETA-AMERICANA L. (BLATTARIA, BLATTIDAE), ULTRASTRUCTURAL AND BIOCHEMICAL FEATURES

In 16-17-day-old embryos of Periplaneta americana, the amnion-serosa p enetrates the cavity of the middle intestine, where it forms a cluster of compressed roundish cells, We demonstrated that these cells degene rate throughout apoptosis. The programmed cell death revealed by morph ological and biochemical approaches showed all the apoptotic steps: ch romatin fragmentation and pyknosis, cytoplasm condensation, karyorrhex is, cytoplasm cleavage. Nevertheless, some ultrastructural peculiariti es (atypical heterochromatin arrangement, appearance of nuclear envelo pe protrusions, absence of nucleolar structures) suggest that the apop totic expression partially depends on the biological situation (type o f organism and inducing factors) in which the programmed cell death ta kes place, The presence of histiocytic cells internalizing cell debris , of apoptotic and non-apototic derivation, may be correlated with the importance of recycling substances useful for embryo growth. (C) 1997 Elsevier Science Ltd. All rights reserved.