Ontogenic Development Of Gills In Pre To Post-Flexion Stages Larvae Of Himalayan Snow Trout Schizothorax Plagiostomus (Heckel)

The ontogenic development of gills, including gill arch, gill filaments, and gill rakers in pre to postflexion stages larvae of Himalayan Snow Trout Schizothorax plagiostomus were studied with the objectives that this study could serve as a base for further studies about the early embryonic development and organogenesis in various fish species inhabiting hill stream environments. To obtain the pre to post-flexion stages larvae, an artificial breeding experiment was conducted during September- October on the bank of snow-fed river Alaknanda by stripping method. Further, the development of the gill apparatus was studied histologically, using light microscopy. Hatchling takes place 124-130 hours after fertilization at the incubation temperature of 19-200C. On second dph (day post-hatching), gill arches, gill filaments, and branchiostegal membrane began to differentiate. By the third dph, blood channels were observed in gill filaments as well as in pseudobranch. Formation of secondary lamellae, branchial arteries, elongation of the gill cover, cartilaginous rod formation in the gill arch, and the branchiostegal membrane was discernible by fourth-fifth dph. Pillar cells and afferent and efferent arteries with RBCs in primary and secondary lamellae were observed on the seventh dph. Around the onset of exclusive exogenous feeding (twelfth dph), gill rakers and a group of pillar cells with blood channels were recognizable. Well-organized and functional gill structures with increased number and size of secondary gill lamellae were present among the fifteenth-seventeenth dph larvae. The general pattern of structural and functional development of both the natural site and laboratory-reared larvae was similar, except a large amount of mucous and clustered epithelial cells among the laboratory-reared larvae, which may be due to the physiological as well as environmental stress posed by the adverse physicochemical conditions.

Expression of acetylated tubulin in the postnatal developing mouse cochlea

Acetylation tubulin is one of the major post-translational modifications of microtubules. Stable microtubules are well known to contain acetylated tubulin. Here, we examined the spatiotemporal expression of acetylated tubulin in the mouse cochlea during postnatal development. At postnatal day 1 (P1), acetylated tubulin was localized primarily to the auditory nerve inside the cochlea and their synaptic contacts with the inner and outer hair cells (IHCs and OHCs). In the organ of Corti, acetylated tubulin occurred first at the apex of pillar cells. At P5, acetylated tubulin first appeared in the phalangeal processes of Deiters’ cells. At P8, staining was maintained in the phalangeal processes of Deiters’ cells. At P10, labeling in Deiters’ cells extended from the apices of OHCs to the basilar membrane. Labeling was expressed throughout the cytoplasm of pillar cells. At P12, acetylated tubulin displayed prominent and homogeneous labeling along the full length of the pillar cells. Linear labeling was present mainly in the Deiters’ cell bodies underlying OHCs. Between P14 and P17, acetylated tubulin was strongly expressed in inner and outer pillar cells and Deiters’ cells in a similar pattern as observed in the adult, and labeling in these cells were arranged in bundles. In addition, acetylated tubulin was intensely expressed in stria vascularis, root cell bodies, and a small number of fibrocytes of the spiral ligament until the adult. In the adult mouse cochlea, immunostaining continued to predominate in Deiters’ cells and pillar cells. Immunolabeling formed cups securing OHCs basal portions, and continued presence of acetylated tubulin-labeled nerve terminals below IHCs was shown. Our results presented here underscored the essential role played by acetylated tubulin in postnatal cochlear development, auditory neurotransmission and cochlear mechanics.

Effect of chromium, cadmium and mercury on the gill histology of Clarias batrachus L.

Effect of cadmium (Cd), chromium (Cr) and mercury (Hg) on the gill histology of Clarias batrachus L. was investigated following 28 days exposure to their sublethal concentrations under laboratory condition. Hyperplasia and hypertrophy of the lamellar epithelium, necrosis, partial lifting of epithelial layer, damage of gill ray, oedema of primary lamellae, damage of pillar cells and congestion of blood vessels were the main histopathological changes. In Cd treated fishes the interlamellar spaces were abolished but distended gill rays were characteristics of Cr treatment. Extensive cellular and tissue damages were prominent in Hg treated fishes. DOI: http://dx.doi.org/10.3329/cujbs.v4i1.13383 The Chittagong Univ. J. B. Sci.,Vol. 4(1 &2):13-23, 2009

Gills of juvenile fish piaractus mesopotamicus as histological biomarkers for experimental sub-lethal contamination with the Organophosphorus Azodrin®400

Piaractus mesopotamicus is a freshwater native fish from rivers of the Paraná-Paraguay Basin and of the Pantanal region and has been used for repopulation programs in Brazil. Juvenile fishes were exposed to the sub-lethal dose of 1.08mg/L of the OP Azodrin®400 containing 0.43µL/L of the active principle monocrotophos for 96 h. A frequent pathology in the gills at all times of exposure was epithelial detachment, from minimal until 24 h of exposure, to intense after 48 h of contamination. Deformed pillar cells in the respiratory lamellae leading to irregular blood spaces and blood congestion, as well as hyperplasia and lamellar fusion were observed. These histopathologies suggested that 48 h after T0 was an important time when a reduction in the capability for gaseous exchange with consequent weakening of the fishes' condition could occur. This could impair growth and development of juveniles introduced in water bodies for repopulation programs.