Fine structure of thyroid gland in wild caught female bat Taphozous kachhensis (Dobson) during reproductive cycle

Abstract

The thyroid gland has long been recognized as an important modulator of reproductive function. Both hyper- and hypo-thyroidism are associated with reproductive dysfunction and infertility. In addition, thyroid hormones appear to play a key role in the expression of events that underlie seasonal reproductive cycles. Despite the considerable information is available on the histology of thyroid gland in some of the bats, literature related to study is very few, and further information available on the ultrastructure is also scanty. The specimen of Taphozous kachhensis was collected from Ambai Nimbi. Many collections were made during the breeding season so as to coincide with the time of reproductive cycle and to get an accurate pregnancy record. Thyroid is removed from the bat and cut into 1–2mm piece and immersed in fresh ice-cold 3% gluteraldehyde solution for 2–4h and send for further process. The thyroid gland is more active during estrus than the pregnancy and lactation. The cell organelles observed in follicular cell of thyroid gland indicate more synthetic activity. While during pregnancy and lactation the thyroid gland is not synthetically active but the appearance of more lysosomal bodies during pregnancy indicate the utilization of stored colloid and release of thyroid hormone in blood stream. The parafollicular cells are more developed during pregnancy and lactation than estrus as indicated by ultrastructural characteristics. These cells may secrete calcitonin, serotonin, and somatostatin and may be responsible for controlling the seasonal changes in plasma calcium concentration in this bat.