Abstract
The broad-snouted caiman, Caiman latirostris, is widely distributed in countries of South America. In Brazil it is considered an endangered species because of natural habitat destruction and illegal hunting. In reptiles, the thyroid gland plays an integral part in ecdysis, reproduction, tail regeneration, growth, endocrine function and metabolism rate. The aim of the present study was to characterize the thyroid gland morphology of C. latirostris, based on histochemical and immunohistochemical techniques. The thyroid glands were fixed in Bouin's fluid and serial cross sections were stained with hematoxylin-eosin, Mallory’s trichrome, periodic acid-Schiff (PAS) and Alcian blue (AB pH 1.5 and 2.5). The immunohistochemical technique for 5-HT-IR cells was used. The thyroid gland has a dense irregular connective tissue forms a capsule enveloping the gland. There are several follicular acini of varying size lined by simple cuboidal or columnar epithelium in the thyroid gland. The follicles are connected by interfollicular connective tissue which contains blood vessels. We observed the presence of lymph nodes around the entire gland. There was a positive PAS reaction and negative AB reaction in the colloid. 5-HT-IR cells were detected around the follicle cells. No striking morphological differences were observed between C. latirostris and other domesticated mammals.
Highlights
The broad-snouted caiman, C. latirostris, is widely distributed in countries of South America
The thyroid gland plays an integral part in ecdysis, reproduction, tail regeneration, growth, endocrine function and metabolism rate (DELLOVADE et al, 1995; SCHMIDT-NIELSEN, 1990)
Previous research has shown that the thyroid hormone parameters of reptiles are different from those observed in mammals
Summary
The broad-snouted caiman, C. latirostris, is widely distributed in countries of South America. The thyroid is the endocrine gland responsible for the synthesis and secretion of the hormones thyroxine (T4), triiodothyronine (T3) and calcitonin. These hormones are present in the vertebrate class and have diverse functions. 585-589, Oct.-Dec., 2013 growth and development (EALES, 1979; MC NABB, 1992), as well as energy balance regulation and maintenance of normal reproductive function in mammals (BOSWELL et al, 1994; SCHWARTZ et al, 1996; SHI; BARREL, 1992). The thyroid gland plays an integral part in ecdysis, reproduction, tail regeneration, growth, endocrine function and metabolism rate (DELLOVADE et al, 1995; SCHMIDT-NIELSEN, 1990). Thyroid deficiency, which can occur by embryogenic effects, leads to limited development of the skeletal, muscle and central nervous systems (MC NABB, 1992)
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