Fig. 12 in Morphology of larval and postlarval stages of Priapulopsis bicaudatus (Danielssen, 1869) (Priapulida) from the north atlantic ocean

Fig. 12. Postlarval stages: pharyngeal teeth. A. Overview on everted anterior pharyngeal teeth in a late postlarval stage (V13477), showing three rings of pharyngeal teeth (pt1-3) and the beginning of the scalid region (sc). Note paired teeth in the first ring. B. Overview on everted introvert in a younger postlarval stage (specimen 6 of V13493) with pharyngeal tooth rings 1–4 visible (pt1-4). Asterisks mark the cushion-like base at the inner side of the teeth. C, F, G, J. First-ring pharyngeal tooth in stages of increasing size (C and F from the same specimen V13484, G from specimen 9-2 of V13493, J from V13477). Note the development from a fine median furrow to a broader groove to the complete separation of the tooth (arrows in C, F, G). D, E. Longitudinal section through the upper pharynx in the adult (V13492), showing teeth of different rings (pt1-pt6) and the first scalids (sc). Note the position of first-ring teeth and the largest size of third-ring scalids. H. Magnification of one of the cusps from the tooth shown in J with apical tooth receptors (arrows). I. Surface of one first-ring tooth in the adult (V13492) showing tooth receptors (arrows). K. Tooth receptors on the cusps of tooth shown in C. All images except E SEM.