Transmission and scanning electron microscopy (TEM, SEM) were used to study the ultrastructure of superficial neuromasts in 15 six month old blind cavefish juveniles, Phreatichthys andruzzii (Cyprinidae). In 5 specimens examined with SEM, the number of superficial neuromasts over the fish body (480 to 538) was recorded. They were localized mainly on the head (362 to 410), including the dorsal surface, the mentomandibular region, and laterally from the mouth to the posterior edge of the operculum. Neuromasts were also present laterally on the trunk and near the caudal fin (116 to 140). A significantly higher number of neuromasts were present on the head compared to the trunk (t-test, P <0.05). Superficial neuromasts of the head and those along the trunk were similar in ultrastructure. Each neuromast comprised sensory hair cells surrounded by non-sensory support cells (mantle cells and supporting basal cells) with the whole covered by a cupula. Each hair cell was pear-shaped, 15-21 µm high and 4-6 µm in diameter, with a single long kinocilium and several short stereocilia. Most support cells were elongated, with nuclei occupying a large portion of the cytoplasm. In the margin of the neuromast mantle cells were particularly narrow. Both types of support cells had well developed Golgi apparatus and rough endoplasmic reticulum. The number of hair cells and non sensory support cells of the anterior lateral line (head) did not differ significantly from those of the posterior lateral line (trunk) (t- test, P > 0.05).
Ultrastructure and distribution of superficial neuromasts of blind cavefish, Phreatichthys andruzzii, juveniles
SAYYAF DEZFULI, Bahram;SIMONI, Edi;
2009
Abstract
Transmission and scanning electron microscopy (TEM, SEM) were used to study the ultrastructure of superficial neuromasts in 15 six month old blind cavefish juveniles, Phreatichthys andruzzii (Cyprinidae). In 5 specimens examined with SEM, the number of superficial neuromasts over the fish body (480 to 538) was recorded. They were localized mainly on the head (362 to 410), including the dorsal surface, the mentomandibular region, and laterally from the mouth to the posterior edge of the operculum. Neuromasts were also present laterally on the trunk and near the caudal fin (116 to 140). A significantly higher number of neuromasts were present on the head compared to the trunk (t-test, P <0.05). Superficial neuromasts of the head and those along the trunk were similar in ultrastructure. Each neuromast comprised sensory hair cells surrounded by non-sensory support cells (mantle cells and supporting basal cells) with the whole covered by a cupula. Each hair cell was pear-shaped, 15-21 µm high and 4-6 µm in diameter, with a single long kinocilium and several short stereocilia. Most support cells were elongated, with nuclei occupying a large portion of the cytoplasm. In the margin of the neuromast mantle cells were particularly narrow. Both types of support cells had well developed Golgi apparatus and rough endoplasmic reticulum. The number of hair cells and non sensory support cells of the anterior lateral line (head) did not differ significantly from those of the posterior lateral line (trunk) (t- test, P > 0.05).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
