Anatomy, histology, and histochemistry of the olfactory organ of the Korean shuttles mudskipper Periophthalmus modestus

Abstract

The Korean shuttles mudskipper Periophthalmus modestus has paired olfactory organs on its snout, consisting of anterior and posterior nostrils, a single olfactory canal with sensory and nonsensory epithelia, and a single accessory nasal sac. Its sensory epithelium consists of numerous islets forming a pseudostratified layer and contains various cells: olfactory receptor neurons, supporting cells, basal cells, lymphatic cells (LCs), and axon bundles. The sensory epithelium is a stratified squamous layer comprising stratified epithelial cells, mucous cells (MCs) with glycogen, flattened cells (FCs), LCs, and unidentified cells. Specific structures are as follows: (a) a tubular anterior nostril projecting outward, (b) a slit posterior nostril, (c) an elongated olfactory canal, (d) an ethmoidal accessory nasal sac, (e) axon bundles found only in the basal layer of the sensory epithelium, (f) FCs only at the top of the nonsensory epithelium, and (g) glycogen‐containing MCs. Such structures seem to be unique in that they have not been observed in most teleost fishes spending their whole life in water.

Microscopic research on the olfactory organ of the Far Eastern brook lamprey Lethenteron reissneri (Pisces, Petromyzontidae)

“…Meanwhile, L. reissneri has 19-20 lamellae in number and are different from the sea lamprey P. marinus with 25 (Kleerekoper and Erkel 1960) and other hag shes, Myxine glutinosa, Eptatretus stoutii and E. deani, with 7 lamellae (Theisen 1976). Generally, in teleost sh, the lamellar number of the olfactory organ is species-speci c: absence (Conidens laticephalus of the Order Gobiesociformes, Oryzias latipes and O. sinensis of the Beloniformes, and Periophthalmus modestus, P. magnuspinnatus of the Perciformes), only one (Hemiramphus sajori, Cheilopogon agoo, and Cololabis saira of the order Atheriniformes), up to 120 (Conger myriaster of Anguilliformes) and 230 lamellae (Holopagus guentheri of Perciformes) (Yamamoto 1982;Kasumyan 2004;Kim et al 2019). It was known that the increase of lamellae leads to the increase of distributional area of olfactory receptor neurons (Kasumyan 2004).…”

Microscopic research on the olfactory organ of the Far Eastern brook lamprey Lethenteron reissneri (Pisces, Petromyzontidae)

“…The tube form also may be suitable for its ecology that the sh burrows its body into the sand at daytime during the lifetime from the ammocoetes to the adult stage (Kim and Park, 2002). Kim et al (2019) noted that with a contraction and a relaxation of the accessory nasal sac, the tubular nostril helps generate a force to suck water into the olfactory canal. In addition, Cox (2008) opined that the tubular structure assists to reduce thicker "boundary layer" occurring on the snout surface of inactive shes.…”

“…In shes, the olfactory organ is an essential chemoreceptor that processes smells and deeply related to diverse ecological behaviors: prey detection, feeding, reproduction, predator risk avoidance, home recognition and migration (Hara, 1986). This organ also is a good morphological indicator to re ect aquatic habitat conditions: i) a degree of water volume, a velocity, a turbidity, and a bottom structure as physical factors (Kim et al, 2019) and ii) pH, infective pathogens, hazard materials, and types of chemical odors as chemical factors (Ghosh and Mandal, 2014) and iii) sh's ecology (Yamamoto, 1982).…”

Microscopic research on the olfactory organ of the Far Eastern brook lamprey Lethenteron reissneri (Pisces, Petromyzontidae)

“…The tube form also may be suitable for its ecology that the sh burrows its body into the sand at daytime during the lifetime from the ammocoetes to the adult stage (Kim and Park 2002). Kim et al (2019) noted that with a contraction and a relaxation of the accessory nasal sac, the tubular nostril helps generate a force to suck water into the olfactory canal. In addition, Cox (2008) opined that the tubular structure assists to reduce thicker "boundary layer" occurring on the snout surface of inactive shes.…”

“…In shes, the olfactory organ is an essential chemoreceptor that processes smells and deeply related to diverse ecological behaviors: prey detection, feeding, reproduction, predator risk avoidance, home recognition and migration (Hara 1986). This organ also is a good morphological indicator to re ect aquatic habitat conditions: i) a degree of water volume, a velocity, a turbidity, and a bottom structure as physical factors (Kim et al 2019) and ii) pH, infective pathogens, hazard materials, and types of chemical odors as chemical factors (Ghosh and Mandal 2014) and iii) sh's ecology (Yamamoto 1982). Finally, the above factors may lead the olfactory organ to have some modi cation in morphology, rosette structure, lamellar number and arrangement, and sensory epithelial distribution (Yamamoto 1982;Zeiske et al 1992; Kasumyan 2004).…”