Comparative cytomorphology of maturing amphisbaenian (Amphisbaena alba) and snake (Waglerophis merremii) erythroid cells with regard to haemoglobin biosynthesis

Abstract

A comparativeultrastructural study on organelles involved in haemoglobin (Hb), biosynthesis processing in the course ofAmphisbaena alba (Amphisbaenia, Squamata, Reptilia) andWaglerophis merremii (Ophidia, Squamata, Reptilia) erythroid cells maturation, was accomplished; for this purpose, erythropoiesis was enhanced by phenylhydrazine hydrochloride and saponin, respectively. The fossorial amphisbaenians, which live in an hypoxic environment, denoted a lower metabolic rate than that of snakes; they presented a slow response to intoxication and to anaesthesia, and an apparently slow transformation of erythroid cell organelles for Hb biosynthesis. Iron uptake, probably via transferrin, results in accumulation in the form of siderosomes, which constitute iron sources for haeme biosynthesis. The inner compartment membrane of mitochondria differentiates to a lamellated body, from which a long doubly lamellated expansion arises for ferruginous compounds and globin polypeptides gathering; by folding upon itself the expansion compartmentalises all caught material into a prehaemosomal vesicle, which condenses and changes to a prohaemosome. This stage is followed by a haemosome, wherein haeme and globin assembly and the final Hb molecule formation take place. Basically, haemosomegenesis is very similar in the two squamates, as in other vertebrates, except that amphisbaenian erythroid cells exhibit haemosomes containing Hb molecules temporarily arranged in a transverse disposition, like steps within the organelle matrix.