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Morphology of the Meckel's diverticulum (MD) of broiler chicken was investigated using gross anatomical, histological and transmission electron microscopy techniques. Forty fertile eggs and 100 chicks of Marshall broiler chicken were used for the study. Samples were collected from 6 randomly selected embryos or chicks on embryonic days 14, 17 and 19, and post-hatch days 1, 3, 5, 7, 14, 21, 28, 35, 42 and 56. The results showed that the mean lengths of the small intestine from the gizzard to the MD and from the MD to the ileocecal junction increased steadily with age. On embryonic days 14, 17 and 19, the poorly differentiated tunics of the MD were composed of lamina epithelialis mucosae and indistinct lamina propria mucosae as well as submucosal areas. The tunica muscularis exhibited loose islands of nascent smooth muscle fibres. Whereas on post-hatch day 1, the lamina epithelialis mucosae showed scanty microvilli and enterocytes with large cytoplasmic vacuoles, the MD of 3-day-old post-hatch chicks contained lymphatic tissues in the lamina propria mucosae. On post-hatch day 35, the lamina epithelialis mucosae demonstrated the presence of apoptotic cells while numerous lymphocytes at various stages of differentiation were observed within the lamina propria mucosae and tunica submucosa. In conclusion, the present study has provided clear structural evidence which shows that intense cellular proliferation occurs in the MD of broiler chicken between embryonic days 14 and 19. This organ may play significant roles in immunological surveillance of the gut, and such functions may peak on post-hatch day 35. [ABSTRACT FROM AUTHOR]

Thirty female African catfish of 3, 4, 5, 6, 7, and 8 months (n = 5 per age) cultured in south-east Nigeria were used to investigate ovarian morphology and development using gross anatomical and histological techniques. The results illustrated that the gonadosomatic indices of the African catfish peaked at 7 months of age (20.05 ± 1.45). Histologically, the ovaries of 3-month-old fish exhibited only pre-vitellogenic oocytes, while 4- to 8-month-old fish showed all stages of oocyte development, with predominance of pre-vitellogenic at 4 and 5 months old, and mature oocytes at 6 to 8 months old. The African catfish demonstrated an asynchronous mode of ovarian development. Oocytes representing the primary, secondary, and maturation growth phases were observed. Based on the gonadosomatic index and the histological evaluation of these ovaries, it was suggested that the African catfish mature for spawning at 7 months of age; moreover, its asynchronous mode of ovarian development may indicate that oocyte development and onset of sexual maturity of the catfish may be influenced by the amount and quality of food available in the culture environment. The study has provided essential information on the oogenesis and ovarian development of C. gariepinus, which may be useful for effective production and management of the fish in captivity. [ABSTRACT FROM AUTHOR]