Saumen Kumar Maitra

Bio: Saumen Kumar Maitra is an academic researcher from University of Calcutta. The author has contributed to research in topics: Psittacula cyanocephala & Parakeet. The author has an hindex of 4, co-authored 4 publications receiving 34 citations.

Gonadal Response to Testosterone Propionate during Breeding and Post-Breeding Phases in the Male Blossom-Headed Parakeet, Psittacula cyanocephala (Aves : Psittaciformes)

Abstract: Testosterone propionate (1 mg per 100 g body weight per day) was administered for 15 days, by injection into the pectoral muscles, to male blossomheaded parakeets during both the spermatogenetically active (February-March) and resting (August) phases of the annual cycle. It caused marked testicular atrophy when it was injected in the sexually active birds. In sexually regressed parakeets it resulted in spermatokinesis and differentiation of Leydig cells. It is evident that the same amount of exogenous testosterone may exert, possibly through pituitary gonadotrophic agent(s), either pro- or anti-gonadal influences depending upon the sexual status of the bird.

Stress factors can reverse the pinealostimulatory effect of 6-hydroxydopamine on the pineal gland of blossomheaded parakeet (Psittacula cyanocephala).

Abstract: A study of the pineal gland of adult male blossomheaded parakeets was conducted with the aid of light microscopic examination to determine the influence of stress on pineal cells. It was demonstrated that stress decreased the growth and activity of the pinel cells when induced as hyperosmolality (water deprivation, salt ingestion). This influence on the pineal gland was not inhibited by previous treatment of a sympatholytic agent, 6-hydroxydopamine.

Role of photoperiod and melatonin in the regulation of ovarian functions in Indian carp Catla catla : basic information for future application

Abstract: The major carp Catla catla is a popular freshwater edible fish and an extensively cultured species in India. However, basic information on the physiology of reproduction is lacking in this species. By virtue of its surface feeding habit, it maintains close contact with environmental light, and is a species of choice for the study of temporal organization of reproduction under natural and experimental conditions for understanding environmental and/or endocrine mechanisms that control the annual reproductive cycle. The present review covers information gathered in recent years to emphasize the temporal pattern of reproductive events and the importance of photoperiod and melatonin, a hormone of the pineal gland that links the environment with the endocrine system in the regulation of reproduction. Finally, the outcome of the research is discussed in terms of its direct and indirect applications to aquaculture of this species with a view to manipulate its breeding at a desired time of the year to meet market demand.

Temporal Pattern of Ovarian Activity in a Major Carp Catla catla and its Possible Environmental Correlate in an Annual Cycle

Abstract: Histophysiological studies of the ovary in a hitherto unconsidered major carp Catla catla, included in this investigative treatise, have allowed the present investigators to demonstrate the pattern of annual events in ovarian functions, as well as the inter-relationship between changes in the ovary and environmental conditions. Month-wise studies of cytological features along with various biochemical features of ovarian functions in free-living Catla revealed the existence of precise annual cyclic changes. On the basis of the studies made on gonads, the annual breeding cycle of this fish has been divided into four different phases, namely (a) the preparatory phase (January–March), (b) the pre-spawning phase (April–June), (c) the spawning phase (July–August), and (d) the post-spawning phase (September–December). A detailed analysis of the data employing various exploratory data-analytic techniques was aimed at drawing a possible relationship between the indices of different reproductive events (oogenesis a...

Annual testicular cycle of blossomheaded parakeet, Psittacula cyanocephala (Aves, Psittacidae), under natural environmental conditions

Abstract: Histophysiological studies of the annual testicular events in an Indian Psittaciform bird, blossomheaded parakeet Psittacula cyanocephala, under natural environmental conditions revealed that the bird is a seasonal breeder with a single peak in a year. Active spermatogenesis takes place only during February and March, but maximum seasonal maturation of the Leydig cells occurs at least one month before the onset of active production of sperm. Comparison of the annual cycles of reproductive parameters with those of different climatological variables could show that duration of solar‐day, in contrast to ambient temperature and rainfall, through its cyclicity parallels, though in part, the gonadal cycle of male blossomheaded parakeet.

Cytological studies of the pineal in relation to the annual cycles in the testis and climatological variables of free‐living roseringed parakeets (Psittacula krameri)

Abstract: Cytological studies of the pineal and the testes in free‐living roseringed parakeets (Psittacula krameri) show that the activities of both organs undergo definite annual changes. The features of hyperactivity of pinealocytes were noted during the months of April through September, after which a gradual loss of the signs of cellular activity occurred till March, when the pineal appeared to be highly regressed, followed by an abrupt change in the opposite direction in April to repeat the cycle. On the other hand, studies of the testes indicated that the species attains maximum testicular maturation during March, after which sudden regression occurs and the testes remain in the quiescent state till September when recovery of spermatogenesis takes place and steady growth and development towards the annual peak follow. A significant negative correlation was found between the seasonal values for nuclear diameter of the pinealocytes and each of the studied parameters of testes. Among the considered clim...