Ontogeny of the antennal glands in the crayfish Astacus leptodactylus (Crustacea, Decapoda): anatomical and cell differentiation

Abstract

The ontogeny of the antennal glands was studied during the embryonic and post-embryonic development of Astacus leptodactylus. The future glands arising from undifferentiated columnar cells were detectable at the metanauplius stage EI 150 μm (EI: eye index; approximately 440 μm at hatching). The tubule and labyrinth differentiated in embryos at EI 190 μm, and the bladder and coelomosac at EI 250 μm. At EI 350 μm, the tubule lengthened and divided into proximal and distal sub-regions. In later stages, the gland retained the same morpho-anatomy but the differentiation and size of each part increased. The cells of the coelomosac displayed the cytological features of podocytes in late embryonic development at EI 440 μm. Only small apical microvilli and a few mitochondria were observable in the labyrinth cells at EI 250 μm; by EI 440 μm, these cells presented well-shaped apical microvilli, formed bodies, basal infoldings and mitochondria. In the cells of the tubules and bladder, mitochondria and basal infoldings occurred at EI 440 μm and EI 250 μm, respectively. The differentiation of the tubules and bladder cells suggested that they were involved in active transport at EI 440 μm. Following hatching, the differentiation of the cells and the size of the glands increased. The ontogeny of the antennal glands thus starts in early embryos, the specific cellular functional features being differentiated in the various parts of the glands by EI 440 μm. The antennal glands are probably functional just before hatching, i.e., before the juveniles are confronted with the low osmolality of freshwater.