الفهرس 
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Abstract
number and size of the
follicles as well as the supportive connective tissue. Some new
follicles were originated from the parent follicles by budding as
well as from the ultimobranchial tissue. The follicles took
characteristic distribution within the lobe, the small follicles
The results presented in this investigation elucidate the
histogenesis of the buffalo (Bos bubalis) thyroid gland using 61
fetuses and embryos at different ages ranging from 37—300 days (2
cm — 100 cm CVRL) intrauterine as well as the thyroid gland of 15
buffaloes ranging between 1.5 months - 10 years old, obtained
from the slaughter house. Serial sections of 4 — 6 tim thick were
prepared and stained with different histological stains.
The bilateral thyroid primordium at the early ages of
development appeared as mass of endodermal cells arranged in the
form of cords and clumps supported by connective tissue elements.
By development of the embryo, the size of the thyroid lobe
increased and the cell cords grow due to the active proliferation
of the endodermal cells, during the growth of the cords,
fragmented into shorter portions or clumps.
Few light cells or parafollicular cells were seen firstly at
49 days old embryos (4.5 cm CVRL) scattered between the cell
clumps. They were easily observed at 85 days old fetus (12.5 cm
CVRL) either singly or in groups between the cell clumps as well
as in the follicular wall. They were large spherical, oval or
polyhyderal with light staining cytoplasm and large nuclei.
Mitotic cell divisions were seen in the light cells. They were
originated from the ultimobranchial body.
The ultimobranchial cysts were observed at 49 days old embryo
(4.5 cm CVRL). Discrete ultimobranchial body was seen as compact
cell mass enveloped by connective tissue beside the thyroid lobe
at 146 days old fetus (32 cm CVRL). At 171 days old fetus (43 cm
CVRL) group of cells from the ultimobranchial body were seen
entering the thyroid lobe forming new follicles. Some large cells.