Abstract
During a survey Myxozoa, four specimens of the sheepshead (18 ± 1.5 cm and 59 ± 2.5 g) (Archosargus probatocephalus) were collected in the Ipioquinha river (Maceió/AL). Transmission electron microscopy observations revealed erythrocyte agglutinations in gill capillaries located near spherical cysts containing myxospores of the genus Henneguya. This hemagglutination partially or totally obstructed the gill capillaries. Erythrocytes occurred in close adherence to each other, with a closed intercellular space. A few lysed erythrocytes were observed among agglutinated cells. The reduced lumen of the capillaries was partially filled with amorphous dense homogenous material adhering to the erythrocytes. In addition, heterogeneous masses of irregular lower electron density were observed in the reduced channel of the capillary. The agglutinated erythrocytes appeared dense and homogenous, lacking cytoplasmic organelles. The nuclei had the appearance of normal condensed chromatin masses, generally without visible nucleoli. This occurrence of hemagglutination only in the capillaries located in close proximity to the developing myxozoan cysts suggests that parasite development may be a factor triggering erythrocyte agglutination. This is supported by previous experimental studies that showed a probable correlation between parasitic infections and hemagglutination. Nonetheless, further studies are necessary in order to better understand the physicochemical processes involved in this phenomenon.
Highlights
Fish erythrocytes have been reported to be sensitive to environmental biotic and abiotic factors and their morphological evaluation has been used as a bioindicator for these factors (Ahmed et al, 2020; Galeotti et al, 2015; Witeska, 2013)
Transmission electron microscopic (TEM) observations on the infected tissues further revealed the presence of several agglutinated erythrocytes (EAg) in the gill filament capillaries (Figure 1B-G), which were in close proximity to the cysts
The erythrocyte agglutination (EAg) caused partial or total obstruction of the capillaries, whenever the juxtaposed erythrocytes occupied the totality of the lumen volume (Figure 1B, C)
Summary
Fish erythrocytes have been reported to be sensitive to environmental biotic and abiotic factors and their morphological evaluation has been used as a bioindicator for these factors (Ahmed et al, 2020; Galeotti et al, 2015; Witeska, 2013). Hematology is considered to be a powerful tool for understanding the health of aquatic organisms, in both wild and captive species (Maciel et al, 2016) These environmental factors, as well as morphological alterations and agglutination of erythrocytes, have been experimentally demonstrated to have an influence on several animal species, including fish (Ahmed et al, 2020; Galeotti et al, 2015; Gupta & Poddar, 2014; Larsen & Mellergaard, 1984; Witeska, 2013). Such stress can be triggered by several factors, including infection with microparasites
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology : Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
