Vascular corrosion replicas of chemo-baroreceptors in fish: The carotid labyrinth in Ictaluridae and Clariidae

Abstract

Scanning electron microscopy of vascular corrosion replicas and light microscopy revealed a pair of highly vascularized tissues, the carotid labyrinths, in the dorsal head region of the channel catfish, Ictalurus punctatus, the black bullhead, I. melas, and the walking catfish, Clarias batrachus. The labyrinth consists of a myriad of arterioles that arise from the common carotid artery immediately distal to the origin of the common carotid from the efferent branchial (epibranchial) artery of the first gill arch. The arterioles anastomose with each other to form: (1) the internal carotid artery which supplies the brain, and (2) several anteriolateral arteries that extend into the anterior head. In the ictalurids the common carotid artery emerges from the labyrinth intact and continues anteriorly as the large olfactory artery, whereas in Clarias all postlabyrinthine vessels result from arborization of the common carotid and subsequent anastomosis of the arterioles. Similarities between piscine and amphibian carotid labyrinths and the anatomical proximity of the former with the gills suggest that, in Ictaluridae, the labyrinth has a chemo- or baroreceptor function.

Sensory innervation of the Gills: O2-sensitive chemoreceptors and mechanoreceptors

“…Carotid labyrinths are found in some catfish and are very similar to the carotid sinus of higher vertebrates (Figure 3). Currently, no physiological function as been ascribed to these structures, however, their location, morphology and innervation suggest a sensory role (Olson et al, 1981). …”

The paraneuronal gill neuroendocrine system in ocellated puffer fish Leiodon cutcutia

“…Several strategies for O 2 chemosensing have emerged in vertebrates like carotid body of mammals (Buckler, ; Lopez‐Barneo, Lopez‐Lopez, Urena, & Gonzalez, ; Peng et al, ), carotid labyrinth of amphibians (Kusakabe, ), and fish (Srivastava & Pandey, ; Srivastava & Singh, ). All these structures are homologous (Kusakabe, ; Munshi & Hughes, ; Olson, Flint, & Budde, ; Srivastava, Tripathi, Pandey, & Singh, ).…”

Blood vascular organization of the rat carotid body: A scanning electron microscopic study of corrosion casts.

“…Recently, some authors have employed a vascular corrosion casting/scanning electron microscope technique (MURA-KAMI, 1971), and examined the microvasculature of the body in the fish (OLSON et al, 1981), the frog (KOBAYASHI and MURAKAMI, 1975;WEIGELT and ACKER, 1977), the water lizard and the salamander (NoGUcHI and KOBAYASHI,1977), the cat (KELLER et al, 1972;SCHAFER et al, 1973;WEIGELT and ACKER, 1977), the rabbit (WEIGELT and ACKER, 1977), and the rat (MCDoNALD and LARUE, 1983). However, the microvascular architecture of the carotid body has not been fully elucidated because of the limited resolution and shallow focus inherent to light microscopy as well as the omission of microdissection in scanning electron microscopy.…”