And Guppy (Poecilia Reticulata) Doaa M Mokhtar* Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assuit University, Egypt
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e Rese tur arc ul h c & a u D q e A v e f l o o Mokhtar, J Aquac Res Development 2015, 6:6 l p a m n Journal of Aquaculture r e u n o t DOI: 10.4172/2155-9546.1000345 J ISSN: 2155-9546 Research & Development Research Article OpenOpen Access Access Comparative Structural Organization of Skin in Red-Tail Shark (Epalzeorhynchos Bicolor) and Guppy (Poecilia Reticulata) Doaa M Mokhtar* Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assuit University, Egypt Abstract The surface architecture and histological organization of the skin of two ornamental fish; red-tail shark (Epalzeorhynchos bicolor) and guppy (Poecilia reticulata) were the main focus of this study. The skin of the two species was composed of epidermis, dermis and hypodermis, although the epidermis showed great variations in their components in the two species. The epidermis of red-tail shark was consisted of epidermal cells, mucous goblet cells, serous goblet cells, club cells, rodlet cells and melanocytes. While, the epidermis of guppy was composed of epidermal cells, mucous goblet cells, eosinophilic granular cells, lymphocytes and melanocytes. The skin of red-tail shark included a variety of sense organs as tuberous receptor organs in the head, superficial neuromasts on the lower lips and the head, canal neuromast in the operculum and the head, and taste buds on the lips, operculum, dorsum of the head and lateral regions of the trunk. However, the skin of guppy was characterized by presence of ampullary organ on the dorsal side of the head, superficial neuromasts on the lips and the head, canal neuromast in the operculum and the head, and taste buds on the operculum, dorsum of the head and trunk regions. These structural peculiarities with histochemical features indicate additional physiological role of the skin of the two species, as the mucous goblet cells in the two species contained a considerable amount of glycoconjugates, whereas the other unicellular gland types, the serous goblet cells and club cells in red tail shark were proteinous in nature. The dermis and hypodermis was consisted of connective tissue, mainly collagenous fibers. Scanning electron microscopy indicated presence of fingerprint like- patterns of microridges of the epidermal cells, pores for lateral canal system, openings of mucous cells and taste buds with specific sensory organs in each fish species. Keywords: Epidermis; Guppy; Red tail shark; Scanning electron different parts of the body focusing on patterns of distribution of the microscopy; Histochemistery; Lateral line system sensory organs of red-tail shark and guppy fish with special reference to histochemistery of glycoconjugates and protein secreting cells Introduction (Figure 1). The skin of a fish is a multifunctional organ and may serve important Materials and Methods roles in protection, communication, sensory perception, locomotion, respiration, excretion, osmoregulation and thermal regulation [1]. The Samples collection skin is self active secretory organ that their cellular components provide many useful products. Goblet cells secrete mucus that keep the body The materials employed in this study were consisted of randomly obtained 16 adult specimens of males and females red- tail shark surfaces moist and protect it from stressors [2], club cells produce the (Epalzeorhynchos bicolor) and guppy (Poecilia reticulata) that purchased alarm substances that initiate the alarm reaction [3] and melanocytes from shops of ornamental fish. The mean standard length was 4.80 ± produce pigments to provide the fish with specific colorations [4]. The 1.01 cm for red-tail shark and 3.05 ± 0.8 cm for guppy. The fish were skin is also a vehicle for coetaneous sense organs that allowed the fish for detection of predators and foods. Among them are taste buds and lateral line system that include neuromasts and electroceptive organs [5]. The skin of fish shows various inter-species difference, as some species have scales and others have special cells. The skin is composed of dermis and epidermis. The comparative anatomy of fish skin, especially the epidermis, has been investigated by light and electron microscopy [6,7]. However, less consideration have been given to the skin of both Figure 1: Showing red tail shark (A) and guppy (B). (Scale bar = 1cm) red-tail shark and guppy fish. Red tail shark (Epalzeorhynchos bicolor) is one of freshwater fish, belongs to family Cyprinidae that originates from the streams and waterways of Thailand. It is characterized by black body and orange tail and its skin is covered with transparent scales [8]. *Corresponding author: Doaa M Mokhtar, Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assuit University, Egypt, E-mail: The guppy (Poecilia reticulata), also known as million fish and rainbow [email protected] fish is one of the most popular freshwater aquarium fish species. It is a Received March 23, 2015; Accepted April 09, 2015; Published May 30, 2015 member of the Poeciliidae, whose natural range is in South America, were introduced to many habitats and are now found all over the world. Citation: Mokhtar DM (2015) Comparative Structural Organization of Skin in Red- Tail Shark (Epalzeorhynchos Bicolor) and Guppy (Poecilia Reticulata) J Aquac Res The body of guppy is transparent and is covered with colorless scales Development 6: 345. doi:10.4172/2155-9546.1000345 and has ornamental dorsal and caudal fins. Guppies are used as a model Copyright: © 2015 Mokhtar DM. This is an open-access article distributed under organism in the field of ecology, evolution, and behavioural studies [9]. the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and The aim of this study was to assess the morphology of skin at source are credited. J Aquac Res Development ISSN: 2155-9546 JARD, an open access journal Volume 6 • Issue 6 • 1000345 Citation: Mokhtar DM (2015) Comparative Structural Organization of Skin in Red-Tail Shark (Epalzeorhynchos Bicolor) and Guppy (Poecilia Reticulata). J Aquac Res Development 6: 345. doi:10.4172/2155-9546.1000345 Page 2 of 8 deeply anaesthetized with benzocaine (4 mg∕ L) and decapitated. Pieces AB (Figure 2D). The density of mucous cells was 10/100 µm (Table 1). of skin from dorsum sides of head, snout, operculum, lips, lateral At the snout: The epidermis was of less thickness; 44 µm (Table parts of the trunk regions and tail region were excised and rinsed in 1) and characterized by large number of club cells in mid epidermal physiological saline. level and numerous PAS-positive mucous goblet cells. The density of Histological and histochemical examination mucous cells was 8/100 µm (Table 1). Tuberous receptor organ was distributed at this region and appeared as spherical structure of sensory Samples for histological technique were dissected at 1×1×.05 cm cells surrounded by a cellular capsule. Melanocytes were randomly and were immediately fixed in Bouin's fluid for 22 hours. The fixed distributed in the dermis (Figure 2E). materials were dehydrated in an ascending series of ethanol, cleared in methyl benzoate and then embedded in paraffin wax. Serial sections of At the operculum: The epidermis was 42 µm in thickness (Table the entire fish at 5-8 µm in thickness were cut and stained with Harris 1). The mucous goblet cells were restricted on the superficial layer. The haematoxylin and Eosin for general structure, Crossmon's trichrome cells were positive with PAS-AB stain. The density of mucous cells was for collagenous fibers. For carbohydrates histochemistry, sections were 8/100 µm (Table 1). Taste buds were observed as pale staining, pear- stained by combined Periodic Acid–Schiff (PAS) technique and Alcian shaped structures consisting of columnar sustentacular cells with dark blue (pH 2.5). Representative sections were stained with bromophenol nuclei alternated with fusiform sensory cells with light nuclei and blue, performic acid-methylene blue and Mallory triple stain for associated with small pyramidal basal cells and surrounded by marginal detection of proteins [10]. cells. Melanocytes were observed as a continuous layer at the dermal Morphometery Red tail shark guppy Body regions Thickness of Density of Thickness of Density of Mean thickness of the epidermis (µm) and density of mucous the epidermis mucous the epidermis mucous cells∕ cells/100 µm of the epidermis in all selected regions in the two fish (µm) cells∕ 100 µm (µm) 100 µm species were recorded ± SE. Lower lip 51.3 ± 4.1 12.2 ± 2.4 36.1 ± 2.3 14.8 ± 2.3 Upper lip 65.2 ± 5.0 10.5 ± 2.7 58. 2 ± 3.6 12.0 ± 2.3 SEM preparation Snout 44. 5 ± 3.9 8.1 ± 2.8 38. 6 ± 3.0 8.6 ± 1.9 The skin of all head regions of both species were immediately Operculum 42.2 ± 2.8 8.9 ± 2.6 30. 8 ± 1.9 8.5 ± 2.8 washed by 0.1 M Na-cacodylate buffer. Then they were fixed in a Dorsum of head 38.6 ± 3.6 8.3 ± 1.4 36. 5 ± 2.8 10 ± 1.8 mixture of 2.5% paraformaldehyde and 2.5% glutaraldehyde in 0.1 M Trunk 18.0 ± 2.2 4.5 ± 1.0 11. 6 ± 2.4 6.3 ± 1.3 Na-cacodylate buffer, pH 7.3 for 4 hours at 4ºC. Thereafter, they were Tail 40. 5 ± 3.7 2.2 ± 1.5 39. 4 ± 4.4 14.7 ± 3. 7 washed in the same buffer used and post-fixed in 1% osmic acid in 0.1 Table 1: The mean thickness of epidermis (µm) at different body region and the M Na-cacodylate buffer for further 2 hours at room temperature. The density of mucous cells∕100 µm of the epidermis in both fish species.