Fig. 2
Generalized diagram of the testis of acorn worms; based on [14, 22,23,24,25]. ac, amoebocyte; cbl, coelothelial basal lamina (outer); ep, ectodermal epithelium; gbl, basal lamina of the germinative epithelium (inner); gnp, gonad pore; hs, haemal sinus; ic, interstitial cell; mc, muscle cell; sc, spermatocyte; sg, spermatogonium; st, spermatids; sz, spermatozoa; tc, trunk coelom; yc, yolk cell