Intl. J. of Molecular Zoology, 2013, Vol.3, No.2, 4
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9
http://ijmz.sophiapublisher.com
4
Research Report Open Access
Seasonal Variation in Thyroid Gland of the Female Bat,
Taphozous Kachhensis
(
Dobson) During Pregnancy
Pankaj Chavhan
1
,
Amir Dhamani
2
1
Department of Zoology, N. H. College, Bramhapuri 441206
2
Department of Zoology, S. S. S. Sci. College, Ashti 442707
Corresponding authors email:
panksphd@gmail.com
;
Authors
International Journal of Molecular Zoology, 2013, Vol.3, No.2 doi: 10.5376/ijmz.2013.03.0002
Received: 26 Dec., 2012
Accepted: 9 Jan., 2013
Published: 25
Jan., 2013
Copyright: © 2013, Chavhan et al. This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Chavhan et al., 2013, Seasonal Variation in Thyroid Gland of the Female Bat,
Taphozous Kachhensis
(
Dobson) During Pregnancy, Intl. J. of Molecular
Zoology, Vol.3, No.2, 4
-
9
(
doi: 10.5376/ijmz.2013.03.0002)
Abstract
The aim of present study is to compare the changes in thyroid gland during the reproductive cycle of the female bat
Taphozous kachhensis
.
The thyroid gland of the bat is studied morphometrically and histologically, it showed marked seasonal
variation in weight, quantity of colloid, epithelial cell height and plasma concentration of thyroid hormones. The thyroid gland is a
symmetrical, bilobed, and located on the lateral side of the trachea, between the first and the third tracheal rings, connected by an
isthmus. The mean weight of the noted lobes was (2.240±0.121) mg, (2.88±0.05) mg and (2.704±0.067) mg, during early pregnancy,
mid pregnancy and late pregnancy respectively. The thyroid hormone shows marked seasonal variations. During early pregnancy
there is rise in the level of TSH (1.7 ng/mL) but the slight decrease in the level of T3 (54 ng/mL) and T4 (2.9 ng/mL) was noticed.
The level of TSH and T4 was decreases during mid pregnancy but the increase in the level of T3 was noticed and it is highest as
compare to other stages and it is found to be 1.4 ng/mL, 1.5 ng/mL, 69 ng/mL respectively. During late pregnancy, TSH and T3
concentration decreases but the increase in the level of T4 was observed and it is found to be 0.9 ng/mL, 60 ng/mL, 2.9 ng/mL
respectively. The diameter of colloid in small, medium and large follicle during early pregnancy and late pregnancy were 28 µm, 56
µm, 96 µm and 36 µm, 60 µm, 72 µm respectively. The epithelial cell heights of small, medium and large size follicles during early
pregnancy and late pregnancy were 3.6 µm, 4 µm, 8 µm and 4 µm, 8 µm, 8 µm respectively.
Keywords
Bat (
Taphozous Kachhensis
);
Gross anatomy; Histology; Thyroid gland; T3; T4
Introduction
The thyroid gland secretes thyroglobulin, triiodothyronine
and thyroxin hormones (Banks, 1993). Thyroxin plays
an important role in metabolism of the animal body.
Thyroid gland comprises of follicles lined by
follicular cells and the interfollicular space was filled
with connective tissue (Leeson and Leeson, 1970).
The thyroid gland has the ability to concentrate large
amount of iodine for the synthesis of thyroxin and
thyroid hormones appear to play a key role in the
expression of events that underlie seasonal
reproductive cycles (Turner, 1966). The thyroid gland
has been studied in many seasonally breeding
microchiropteran bats by Kwiecinski et al. (1991),
Damassa et al. (1995) and these studies indicate that
the thyroid increases activity late in the winter or early
spring, is active throughout the summer, and regresses
by autumn. Such an activity cycle is commonly found
in most seasonally breeding mammals.
The hormones secreted by various endocrine glands
are directly or indirectly involved in normal
functioning of the reproductive processes in various
species and the thyroid hormone appear to be vital in
reproduction.
Thyroid hormones are unique because they exert
effects within almost every tissue of the body. The
thyroid hormone deficiencies have resulted in a
number of abnormalities with respect to growth,
development, behavior, metabolism and reproduction.
Schwartz et al. (1992), Shi and Berrel (1992) have
reported that the T3 is essential for mammalian
reproduction in cattle, the deficiency of which result
into female infertility. It has also been reported that a