STUDY ON PRENATAL DEVELOPMENT OF ADRENAL GLAND OF SHEEP (Ovis aries)
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Date
2016-10
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
The present work was conducted to observe the histomorphogenesis and
histochemical changes in adrenal parenchyma. A total of 63 healthy embryos and
foetuses irrespective of their sex were collected from pregnant sheep slaughtered from
local slaughter houses of Tirupati and were divided into three groups as per their
estimated approximate age.
The adrenal glands attained a harvestable size around 46-47 days of gestation.
At this age, the adrenals were rounded and pin head shaped and pink in colour and in
later stages of development the right adrenal was pyramidal and left adrenal was bean
shaped. The left adrenal was heavier, thicker and longer than the right adrenal gland in
all groups. The primordium of the adrenal was first noted in 38 days old embryo and
was placed cranial to metanephron and ventral to aorta. At 54 days of gestation, thick
connective tissue capsule was observed. Collagen fibres, reticular fibres and nerve
fibres were noticed in the capsule. However, elastic fibres were not noticed in adrenal
gland through out the gestation. The mean thickness of the capsule in group II was
69.196μm ± 12.97 and in group III was 96.003μm ± 16.99 respectively.
At 54 days of gestation, zona glomerulosa was formed. At 75 days of gestation,
two zones were observed in the cortex i.e, outer zona glomerulosa and inner zone
fasciculata. The zona reticularis is not distinctly seen in all the age groups. The
thickness of the cortex increased steadily with the age of the foetus. The migration of
medullary cells through the capsule was noticed at 60 days of gestation. At 100 days of
gestation distinct medulla was observed in the centre of the gland. The chromaffin
granules number and their size increased as the age advanced. Noradrenaline and
adrenaline producing cells were also observed in the medulla. A large medullary vein
was noticed in the centre of the gland.
Histochemical studies of adrenal gland revealed that glycogen content was more
in cortical cells especially in glomerulosa cells. The capsule showed intense positive
reaction for PAS whereas cortex and medulla showed moderate to weak PAS reaction.
In the present study, an intense reaction for acid mucopolysaccharides was observed in
cortical trabeculae. The reaction for acid mucopolysaccharides was very weak or even
absent in adrenal parenchyma. The capsule and medulla were completely devoid of
lipids whereas cortex showed moderate reaction. The capsule and cortex showed
intense reaction and medulla showed moderate reaction for alkaline phosphatase. The
capsule and cortex showed weak to moderate reaction and medulla showed intense
reaction for acid phosphatase in all the age groups.
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