Premium
Apertures of Craniate offactory Organs
Author(s) -
Bjerring Hans C.
Publication year - 1989
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1989.tb01056.x
Subject(s) - anatomy , biology , vomeronasal organ , hagfish , epidermis (zoology) , appendage , nasal cavity , olfactory system , vertebrate , neuroscience , biochemistry , gene
The olfactory organs of craniates appear to derive from an anterior pair of erstwhile branchiothyria and their adjacent epidermal, neurogenic placodes. The organ is termed saccus nasalis if its source is the ectobranchial invagination of the branchiothyrium, and the saccus rhinalis if its source is the entobranchial evagination of the branchiothyrium. Nasal sacs occur in gnathostomes and lampreys, and rhinal sacs in hagfish. It is difficult, therefore, to avoid the conclusion that the olfactory organ has evolved more than once. The rhinal sac has only one aperture, the postica, which represents an internal branchiothyric orifice. Partial fusion of the right and the left rhinal sac led to the development of a postica communis. The nasal sac has either one, two or three apertures. Altogether there are nine different aperturae sacci nasalis, viz. the naris, the foris, the tremiscus, the two nariculae, the rimilla, the portula, the opiscus and the janua. The janua represents an external branchiothyric orifice and occurs in lampreys. The naris and the foris arose by subdivision of the orifice from which the janua emanated; they are found in osteolepipods. The naris is also found in urodeles, porolepiforms and some teleosts. The incurrent and excurrent naricules resulted from bipartition of a naris and are present in actinopterygians, coelacanthiforms, brachiopterygians, dipnoans and elasmobranchiomorphs. Of the four remaining openings of the nasal sacs the rimilla results from an inpushing of the epidermis, the portula from an outpocketing of the nasal sac, and the tremiscus from a combination of two such movements, the one inward and the other outward. Rimillae occur in cyprinodonts, anurans, urodeles, caecilians and porolepiforms, portulae in uranoscopids and bathydraconids, and tremisci in urodeles and porolepiforms. The opiscus, finally, is the opening through which the vomeronasal organ communicates with the oral cavity. It occurs in most lizards and snakes and probably also in some mammals.