Animal Molecular Breeding 2016, Vol.6, No.4, 1-10
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Figure 10b Cerebellum of the GF showing, Arrowhead; Stellate cell, Black arrow; Nerve cell, (Week 4 Post-hatch) CFV,
Magnification: X400
Figure 11 Cerebellum of the HGF showing, (A): Arrowheads: Dendrites, 4; White matter, H&E (8 weeks post-hatch) Magnification
X 140 (B): 1; basket cell, 2 and 3; Purkinje cells, Arrowheads; Dendrites, H&E (8 weeks post-hatch) Magnification X200 (C): Arrow;
Stellate cell, CFV (8 weeks post-hatch) Magnification X200
4 Discussion
Cerebellar development is unique because its dysfunction leads to pronounced disturbances in movement, posture
and balance since it houses most of the neurones found in the brain. In the grey breasted HGF, the cerebellum was
first observed on the dorsal surface of the pons on day 11 of pre-hatch. In the domestic chicken, Serdar and Emrah
(2010) observed that the cerebellum was first noticed on the 7th day of incubation. These variations might be as a
result of differences in their length of incubation, 21 days for the domestic chicken which will require shorter days
to have the cerebellum formed as against the 28 days for the HGF. Cerebellum develops after closure of the neural
tube from the fourth vesicle of the five vesicles on the dorso-lateral part of the alar plates of the metencephalon
(Mail and Reckess, 2002). On day 18 and 27 of incubation, there occurred as a result of the increase in size, shape
and orientation of the cerebellum. These changes might have occurred as a result of the increase in the temporal
part of the skull so as to accommodate the brain. The vermis progressively becames distinct including the
cerebellar auricles. This is in agreement with observations by Portman and Stingelin (1961) that brain weight and
size always increased with increase in body size but varied from one species to another. On the 27th day, the
middle part of the cerebellum was relatively larger and somewhat spherical to convex dorsally. This is in
agreement with the observation of Ransom and Clarke (1974) that the symmetrical limb movement of reptiles was
as a result of their well-developed middle cerebellar portion corresponding to the vermis which is well developed
in birds that fly than the flightless. The keets of the grey breasted HGF are precusians, suggesting that they need a
well-developed vermis which is responsible for limb control. The large cerebellar auricles observed agrees with
finding of Sengluab (1952) that the auricle tends to give a greater degree of body orientation in birds. Whitlock
(1952a) had traced degenerating secondary fibers to the auricles following lesion of cranial nerve VIII vestibular
