Browsing by Author "Kimaro, Wahabu"

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Histomorphological damage in the small intestine of wami tilapia (oreochromis urolepis) (norman, 1922) exposed to microplastics remain long after depuration
(MDPI, 2022) Mbugani, John J; Machiwa, John F; Shilla, Daniel A; Kimaro, Wahabu; Joseph, Dativa; Khan, Farhan R
The histopathological effects of microplastics (MPs) in the gastrointestinal tracts of fish following long-term exposure and depuration are relatively understudied. This study investigated histomorphological damage in the small intestine of Oreochromis urolepis larvae following 65 d exposure to 38–45 μm of polyethylene microspheres (PE MPs) and after a recovery period of 60 d. Larval fish were assigned to each treatment group (control, 1, 10 and 100 PE MPs), where ingestion and degenerative changes in the small intestine were examined using a routine hematoxylin and eosin staining technique. The results highlighted significant PE MPs ingestion and retention proportional to exposure dose (χ 2 = 49.54; df = 2). Villi height and width and epithelial cell height were significantly affected and differed between treatment groups. Indices of damage to the small intestine organ (χ 2 = 47.37; df = 2; p < 0.05) and reaction patterns of villi, epithelial, goblet and cryptic glandular cells, leucocytic infiltration and blood congestion revealed significant occurrence of alteration as PE MPs exposure dose increased. After the recovery period, no PE MPs were observed, and villi height, width and epithelial cells showed recovery with no significant difference between treatment groups. Organ indices declined (χ 2 = 12; df = 2; p < 0.05) but remained significantly different between treatment groups, largely due to leucocytic infiltration (χ 2 = 9.08; df = 2; p < 0.05). The study demonstrated that microplastics induced small intestinal wall degeneration, but recovery in young fish occurred slowly. The damage likely compromised its digestive function, which may affect growth and reproduction. This requires further research.
Morphological changes in the sperm storage tubules of the japanese quail exposed to methy-2- benzimidazole carbamate
(Anatomy Journal of Africa, 2016) Kimaro, Wahabu
The current investigation was an attempt to establish the effect of various doses of methyl-2- benzimidazole carbamate (carbendazim®) on the morphology of the Sperm Storage Tubules (SST) in the Japanese quail (Coturnix coturnix japonica). Carbendazim® in sunflower oil base was administered orally at doses of 0mg/kg (control), 25mg/kg, 100mg/kg, 400mg/kg and 800mg/kg body weight. Tissue samples from Uterovaginal junction were processed for both light (LM) and Transmission electron (TEM) microscopic study following standard procedures. The result showed that, at LM level, no histopathological changes were observed at a dose of 25mg/kg b.w.t. A significant decrease in SST width and luminal diameters was observed at doses of 100mg/kg and 400mg/kg b.w.t (p < 0.05). In addition, doses of 400mg/kg and 800mg/kg b.w.t caused leukocytic infiltration and hyperaemia in the lamina propria-submucosa. At these doses SST were devoid of spermatozoa. TEM results showed pyknosis, swollen mitochondria, vacuolation and increased number of lysosomes in degenerating SST. The observed morphological changes indicate the ability of carbendazim to disrupt structural integrity of SST as well as its storage capacity. This poses a great threat to the fertility of exposed birds and thus care must be taken to reduce environmental contamination.
Time-course effects of carbendazim in the infundibulum of the japanese quail (coturnix coturnix japonica)
(Anatomy Journal of Africa, 2016) Kimaro, Wahabu
The present study was undertaken to establish the long-term effect of a single dose of carbendazim in the tubular region of the infundibulum of Japanese quail using scanning (SEM) and transmission (TEM) electron microscopy. At a dose of 400mg/kg bodyweight, carbendazim in sunflower oil base was administered orally to mature Japanese quails. The control group received the oil base only. The effects of carbendazim on ultrastructural features of infundibulum were examined in spatial temporal periods post-exposure. At SEM level, loos of cilia were observed from 5 days post-exposure. At TEM level, pyknosis, karyorrhexis, swollen mitochondria, dilated RER cisternae, increased number of lysosomes and vacuoles were observed from 24 hours post-exposure. Compound cilia and loos of striated rootlets were also observed. Thickening and duplication of the basal lamina were identified from 12 days post- exposure. These results suggest oviductal regression due to carbendazim toxicity and signs of epithelial recovery at later stages post-exposure.