Fig. 3

Structure of the olfactory organ of P. aethiopicus (a1-a7) and L. paradoxa (b1-b2). (a1) A sagittal section of the olfactory organ stained with hematoxylin–eosin, showing lamellae suspending from the dorsal wall. Dorsal is top, rostral is left. Recesses are found at the base of lamellae (arrows). (a2) The lamellar OE stained with hematoxylin–eosin showing round nuclei of the olfactory receptor cells (ORC) in the basal to middle layer, and oval nuclei of the supporting cells (Sp) in the upper layer. The lamellar OE and non-sensory epithelium (asterisks) are arranged alternately. (a3) A recess stained with hematoxylin–eosin consisting of the recess epithelium (RecE) which contains several layers of cells with round nuclei, and the glandular epithelium (GE) which contains eosinophilic cytoplasm and basally located round nuclei. (a4) The layer of ORCs immunopositive for NCAM and the non-sensory epithelium (asterisks) immunonegative for NCAM. (a5) The RecE immunopositive for NCAM and the GE immunonegative for NCAM. (a6 and b1) The basal layer of lamellar OE is immunopositive for Gαo. (a7 and b2) Most ORCs in the RecE are immunopositive for Gαo. GE is immunonegative for Gαo. Scale bars: 500 µm in (a1), 50 µm in (a2–a7, b1, b2)