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O. V. Oommen ¹, P. Sreejith ¹, R. S. Beyo ¹, L. Divya ¹, A. S. Vijayasree ¹, M. Manju ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, IN

Abstract

Our studies describe the effect of T₃ on the regulation of mitochondrial metabolism, lipid peroxidation and antioxidant enzyme homeostasis in a fresh water teleost, Anabas testudineus. These experiments suggest the possibility that certain of the clinical and biochemical manifestations of T₃ can be attributed to a direct effect of T₃ on mitochondria. Thyroid hormone enhances mitochondrial ATP production rate in the highly oxidative tissue such as liver. These in vitro and in vivo studies substantiate and confirm the earlier reported T₃-induced oxidative metabolism in lower vertebrates. These induced oxidative metabolisms create oxidative stress in tissues. This confirms that T₃ has an immediate response in in vivo and in vitro system on energy adjustment in the fish, A. testudineus. Tri-iodothyronine is also capable of combating the oxidative stress by activating the antioxidant system to remove the ROS. Tri-iodothyronine appears to have a dual role, as a stimulator of oxidative process and as a regulator of antioxidant enzyme activity. This establishes another example for the multi-functional role of T₃ in lower vertebrates also. However, the precise mechanism of action remains to be understood. The protein expression study revealed that T₃ administration in fish creates hypermetaolic state. This hypermetabolic state creates oxidative stress in fish. To maintain the homeostasis of the fish, physiology the main antioxidant CuZn SOD is directly altered. Due to augmented SOD utilization, expression of CuZn SOD is diminished in fish liver and brain. These findings conclude that thyroid hormone effectively maintains physiological status of fresh water fish. It is obvious that thyroid hormones have an over all effect on metabolism in responsive tissue and that their effect is a direct one. Theses studies establish multi-functional role of T₃ in lower vertebrates.

Keywords

Anabas testudineus, Free Radicals, Mitochondrial Respiration, Superoxide Dismutase, Thyroid Hormone, Tri-Iodothyronine.

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R. S. Beyo ¹, L. Divya ¹, K. Ramachandran ¹, O. V. Oommen ¹, M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram, 695585, IN
2 Derpartment of Animal Science, Bharathidasan University, Thiruchirappalli, 620 024, IN

Abstract

Corpus luteum is a transient and well known endocrine gland that develops from the ruptured follicles in the female vertebrate ovaries, immediately after ovulation. A major source of progesterone, this gland is concerned with gestation in the viviparous animals and retention of eggs in the oviduct in the oviparous species. Caecilians are a group of amphibians with several aspects of reproductive anatomy and physiology unique. In as much as corpus lutem has been described in a few caecilian species, it has not been described from ultrastructural perspectives. Here in we describe the ultrastructural features of corpus luteum of a single specimen of Gegeneophis ramaswamii, which was captured immediately after it laid the eggs. The corpus luteum is formed by three types of cells, namely granulosa lutein cells, thecal lutein cells and phagocytic cells. Both the types of lutein cells are characterized by abundant mitochondria, endoplasmic reticulum and Golgi apparatus. The granulose lutein cells abound with discrete granules. The phagocytic cells engage in phagocytosing cell debris. The cellular features are discussed in relation to information from oviparous as well as viviparous vertebrates. Thus, the paper describes, for the first time the corpus luteum of a caecilian from ultrastructural perspectives.

Keywords

Corpus Luteum, Endothelium, Theca, SER, Follicle Cell.

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O. V. Oommen ¹, M. Smita ¹, R. S. Beyo ¹, M. G. Jancy ², R. Girija ², M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, 695 581, Thiruvananthapuram, IN
2 Department of Animal Science, Bharathidasan University, Thinjchirappalli- 620 024, IN

Abstract

Caecilians, of the order Gymnophiona in the Lissamphibia, are circumtropically distributed across most moist tropical regions of the world. Gymnophiona are among the least understood terrestrial vertebrates and have received lesser attention than the other two orders of lissamphibians, the Urodela and Anura. Spermiogenesis, known as spermateleosis in lower vertebrates, is the transformation of the round spermatid into a highly specialized spermatozoon with a species-specific structure. Spermateleosis and sperm morphology of two species of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani, from the Western Ghats of Kerala, India, were studied using light and scanning electron microscopy. The cyst morphology is described in ten steps. We also report the sperm transporting course in this enigmatic amphibian in addition to localizing sperm in the kidney. This confirms the transport of sperm through the kidney.

Keywords

Amelwid Cells, Caecilians, Connective Tissue Strand, Cyst, Sertoli Cells, Spermatids, Spermatozoa, Sperm Transport.

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R. S. Beyo ¹, O. V. Oommen ¹, M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620 024, IN

Abstract

This study is the first to describe the major stages of follicles of a caecilian from ultrastructural perspectives. The female reproductive system of Ichthyophis tricolor is described. Assembly of the folhcles involves the origin of primary oocytes from oogonia and the pre-granulosa cells from ovarian stroma, each from a separate nest, and the arrival of pre-granulosa cells around the meiotic oocyte to become granulosa cells. Appearance of a perivitelline space between the oocyte and the granulosa cells marks the beginning of pre-vitellogenic follicles. Macrovilli arise from the granulosa cells and ramiiy in the perivitelline space. In the vitellogenic follicles the macrovilli are further more prominent, and microvilli arising from the oolemma intercalate between the macrovilli. Yolk platelets appear in the cortical ooplasm, which are initially small and scattered but later the smaller ones fuse, and lipid and glycogen are added on resulting in large yolk platelets. The material of the vitelline envelope appears in the perivitelline space, which later condenses into the vitelline envelope. Some of the follicles undergo atresia when the granulosa cells become atrophied, and amoeboid cells from the theca enter the ooplasm and phagocytose the yolk.

Keywords

Caecilian, Follicle, Granulosa Cells, Ichthyophis tricolor, Oocyte, Ovary.

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