Correlation between granulocytes and tunic cuticle of Ciona intestinalis (Tunicata, Ascidiacea) as evaluated by microscopy

The tunic is a peculiar integumentary tissue covering the epidermis of ascidians and other tunicates. It is an extracellular matrix whose outermost surface is revealed to be a continuos layer called tunic cuticle, composed of electron dense fibrous materials. Mechanisms occurring during the growth of the animal after metamorphosis, must assure the maintenance of the thin tunic cuticle density and integrity as it represents the primary body surface barrier preventing the mechanical and microbial assaults. Investigations by optical and electron microscopy on tunic samples from young Ciona intestinalis, allowed us to study morphological relationship between the tunic cuticle architecture and granulocytic cellular groups that are located next to it and the involvement of them on its formation.