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Histological studies revealed annual cyclic changes in ovary of Labeo rohita. Oogonial proliferation and recruitment of primary oocytes occured during resting (December-January) and preparatory phase (February-March). Ovarian growth was coincided with the enhancement of temperature and photoperiod from month of April when ovarian wall became thin, vascular supply increased and blood capillaries became conspicuous. These oocytes were transformed to yolky mature follicles during maturation phase (May-June) and attained the maximum diameter during spawning phase (July-August). Ovary underwent regression with decline of water temperature during September-October. Hypertrophid granulosa cells took active part in resorption of yolky oocytes. The new oogonia appeared only after complete resorption of yolky oocytes. This study shows that month-wise changes of photo-thermal conditions are major regulator of ovarian function in Labeo rohita. [ABSTRACT FROM AUTHOR]

Pituitary of Labeo rohita is a small pear-shaped, whitish soft body lying on ventral side of the brain immediately behind the optic chiasma in sella turcica on the floor of cranium. Gonadotrophs of the Indian majopr carp were distributed in the proximal pars distalis (PPD) of pituitary gland. Number of cynophils (gonadotrophs) exhibited wide fluctuations with the ovarian maturation. In fact, acidophils (somatotrophs) predominated during non-breeding phases whereas number of cynophils increased and they became the major cell type of PPD as maturity advanced. These cynophils displayed hypertrophy and varying degrees of granulation as well as vacuolization (degranulation) in relation to ovarian maturation. Some cynophils of PPD that did not exhibit marked hypertrophy or degranulation in relation to maturity were identified as thyrotrophs. [ABSTRACT FROM AUTHOR]

A 30-day feeding trial was conducted to study the antistress ability of dietary Eclipta alba (L.) ethanol extract against acid stress in Labeo calbasu fingerlings. Fingerlings (6.45±1.3 g) were randomly distributed into four treatment groups with three replicates, each, and fed one of four diets containing different levels of E. alba ethanol extract (0%, 0.01%, 0.1%, or 1%). The antistress ability of E. alba ethanol extract was assessed in terms of stress hormones - serum cortisol, glucose, alanine amino transferase (ALT), aspartate amino transferase (AST) - and enzymes - lactate dehydrogenase, malate dehydrogenase, ATPase, superoxide dismutase, catalase - before and after exposure to acidic water (pH 5.5) for 24 h. Serum cholesterol was significantly higher after acid stress than before. The increasing supplementation of E. alba ethanol extract in the diet significantly reduced the cholesterol level both before and after acid stress while similar trends were found in serum cortisol, glucose, ALT, and AST. Glycolytic, gluconeogenic, protein metabolic, and antioxidative enzymes significantly increased after exposure to the acidic water to cope with the resultant stress. Results indicate that E. alba ethanol extract possesses good antistress activity and that dietary supplementation of ≥0.1% E. alba ethanol extract reduces stress in L. calbasu fingerlings exposed to acid stress. [ABSTRACT FROM AUTHOR]