Age Specific Anatomical Studies on the Medulla Oblongata in Post-Hatch Broiler Chicken.

Present study was conducted on 70 day-old broiler chicks which were reared up to 42 days (market age) of post-hatch period. The birds were divided into 7 groups, each containing 10 birds, irrespective of sex. The whole experimental period was divided into seven weekly intervals (days 0, 7, 14, 21, 28, 35 & 42). The birds of age-group I to VII were sequentially euthanized at weekly interval and intact brains were harvested carefully. Grossly, the medulla oblongata was situated behind the optic lobes just ventral to the cerebellum and it became gradually narrowed posterior. Histologically, the medulla oblongata at all the age groups was made up of chiefly the broad bands of nerve fibres, which were longitudinally placed. The nuclei of the medulla oblongata were formed by few multipolar neurons, spindle shape neurons and very few pyramidal neurons supported by few neuroglia cells. On PAS staining a weak to mild lipofuscin pigmentation in neurons of medulla oblongata was observed in day old chicks, while in 42 days old chicks (group VII) moderate pigmentation was recorded. [ABSTRACT FROM AUTHOR]