Annual testicular cycle of blossomheaded parakeet, Psittacula cyanocephala (Aves, Psittacidae), under natural environmental conditions
TL;DR: 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.
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.
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TL;DR: The results of the present investigation suggest that methyl parathion ingestion is harmful to male gametogenic functions in the studied passeriform bird, and the given pesticide may exert its antigonadal effect by impairing cholinergic functions of the brain and/or testes.
Abstract: Adult male whitethroated munias, Lonchura malabarica (Aves; Passeriformes), were orally administered with methyl parathion (O, O-dimethyl O-(4-nitrophenyl) phosphorothioate), an extensively used organophosphate pesticide, in graded sublethal dose (5 μg-, or 10 μg-, or 20 μg/100 g body wt/day) for variable durations (1-, 5-, or 10 day/s) during their peak reproductive activities in an annual gonadal cycle. No subtle changes in the feeding behavior, mobility, and body weight were noted between the control and different groups of pesticide-fed birds. As a result of the treatment, the paired testicular weight became reduced significantly only after 10 days at 10 μg- and 20 μg dose levels, but significant decrease in the number of tubules containing healthy germ cells occurred even after single administration of methyl parathion (MP) at the lowest dose (5 μg/100 g). With the increase in dose and progress of treatment, the number of tubules with healthy germ cells became gradually decreased. The activity of acetylcholinesterase (AChE) in both the brain and testes of MP-treated birds was inhibited in a dose and duration dependent manner. A significant negative correlation was observed between the number of tubules containing degenerated germ cells in the testis and the AChE activity in both the brain and testes of MP-administered birds. However, no remarkable changes in the cytomorphological features, including the nuclear diameter of Leydig cells, were noted in any testis of the pesticide-treated munias. The results of the present investigation suggest that methyl parathion ingestion is harmful to male gametogenic functions in the studied passeriform bird, and the given pesticide may exert its antigonadal effect by impairing cholinergic functions of the brain and/or testes.
37 citations
TL;DR: The present findings apparently establish the dependency of the uropygial gland of the male wild passerine bird upon the seasonal fluctuation of its testicular activity, although the possible participation of thyroidal hormones an...
Abstract: Weight and lipid content of the uropygiai gland of male Pycnonotus cafer (Linnaeus), a common subtropical wild passerine bird exhibit seasonal variations, roughly coinciding with those of testicula...
24 citations
TL;DR: The results indicate that the duration of daily Photoperiod probably has no important role in the seasonal recrudescence of spermatogenesis, but the same factor may have certain uses in promoting further sperMatogenesis in the testes of the bird.
Abstract: Adult male Blossomheaded Parakeets were held under artificial very long (22L) and very short (2L) daily pohoto periods either for 45 days or for both 45 days and 90 days during different phases of the annual gonadal cycle. These experiments were designed so as to establish: (i) whether this is at all photosensitive or not; and (ii) if photosensitive, the importance of the duration of the photoperiod in the periodic activation of the testes of the bird. Longer periods of artificial light or darkness did not affect spermatogenesis throughout the preparatory and early progressive phases (May through October) of the annual reproductive cycle. But the testes of the parakeets became precociously mature when the birds were held in long photoperiods, for 45 days, during the late progressive phase (Nov. -Jan.). The same photoperiodic regimen caused testicular involution when the treatment was extended up to 90 days. During the same reproductive phase retardation of testicular growth was attested with the studies of the birds kept in darkness for 45 days. Under identical photoschedule the occurrence of spermatogenesis was noted in a few tubules of the testes of birds held in darkness for 90 days. During the prebreeding phase (Jan. -Feb.) the testes of the long photoperiodic birds were spermatogenetically active after 45 days treatment, but regressed when the treatment was continued for 90 days. Long daily darkness periods for durations of 45 and 90 days during the same reproductive phase induced retardation of testicular growth. None of the used photoschedules, i. e. 22L 2D or 2L 22D, appeared to affect testicular regression, a time bound natural phenomenon of the free-living species, when the birds were treated for 45 days after the breeding phase (Feb. -March) of the annual gonadal cycle.The results indicate that: (i) the duration of daily Photoperiod probably has no important role in the seasonal recrudescence of spermatogenesis, but the same factor may have certain uses in promoting further spermatogenesis in the testes of the bird; (ii) influence of the prolonged duration of very long stimulatory photoperiod is inhibitory to the testicular functions of this species; (iii) artificial long or short days cannot affect the periodic testicular involution; (iv) this bird becomes photorefractory during, at least, the preparatory and early progressive phases (May- Oct.) of the annual gonadal cycle; (v) the duration of photorefractoriness is possibly not less than a period of six months. As a tentative unifying hypothesis to be tested, it may be suggested here that in case of the low-latitude male Blossomheaded Parakeets, the duration of the available photoperiod possibly constitutes part of the battery of information used in timing reproductive functions.
16 citations
TL;DR: Cytological studies of the pineal and the testes in free‐living roseringed parakeets show that the activities of both organs undergo definite annual changes.
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...
15 citations
TL;DR: The results suggest that initiation and termination of seasonal gametogenic activity in parakeets are possibly functions of endogenous rhythmicity or extraphotoperiodic environmental factors and that the species has a low photoperiod threshold for induction of testicular growth.
Abstract: Male rose-ringed parakeets (Psittacula krameri) were transferred to a long photoperiod (LP; LD 16:8) or a short photoperiod (SP; LD 8:16) for 45 or 90 days on four dates corresponding to the beginnings of different reproductive phases in an annual testicular cycle, and testicular responsiveness was evaluated by comparison with the testicular volume, weight, seminiferous tubular diameter, and germ cell profiles of birds in a natural photoperiod (NP). Exposure of birds to LP during the progressive phase (November) led to precocious maturation of testes after 45 days, but induced regression at 90 days. After showing retarded gametogenic functions at 45 days, parallel (November) SP birds exhibited an accelerated rate of germ cell formation at day 90. During the prebreeding phase (January), there were no remarkable differences in any features of testes among NP, LP, and SP birds at 45 days, but gonadal involution in LP parakeets and active spermatogenesis in SP birds occurred after 90 days. The testes did not ...
14 citations
References
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Book•
01 Jan 1961
TL;DR: The new Pearse bids fair to become the leader, even amongst so notable a collection of books devoted entirely or largely to histochemical techniques.
Abstract: A. G. E. Pearse is a relative newcomer to the field of histochemistry. He holds an M.D. degree from the University of Cambridge and is now Lecturer in Histochemistry at the Postgraduate Medical School, University of London. One of his first contributions to histochemistry consisted of a critical review of its methodology and interpretation, written for pathologists and appearing in the British Journal of Clinical Pathology 4: 1 (1951). He has also introduced a number of new or modified techniques. Perhaps those having the greatest interest for endocrinologists are presented in a series of papers concerning the demonstration of the glycoprotein hormones of the anterior pituitary gland (Nature 162: 651, 1948; J. Path. & Bad. 61: 195, 1949, 64: 791 & 811, 1952; Stain Technol. 25: 95, 1950). The present volume comprises 17 chapters, beginning with a brief but fairly inclusive history of the development of this branch of science and continuing with 2 chapters on methods of fixation and sectioning, 3 on the staining of proteins, 4 on the demonstration of enzymes, 1 on the use of enzymes as histochemical reagents, and 1 each on carbohydrates, lipids, aldehydes and ketones, pigments, inorganic substances, and physical methods. The book concludes with appendices which give the detailed steps of the histochemical techniques which Dr. Pearse has himself found most useful for demonstrating various tissue constituents. Complete author and subject indices follow. A further valuable feature of the book consists of numerous black-and-white and a few colored photomicrographs illustrating the appearance of sections prepared by some of the histochemical methods discussed. A rash of books devoted entirely or largely to histochemical techniques has appeared in the last few years. Outstanding are the treatises by Lillie (1948), Romeis (1948, 15th ed., German), Glick (1949), Gatenby and Beams (1950, 11th ed.), Gomori (1952), and Lison (1953, 2nd ed., French). In this reviewer's opinion, the new Pearse bids fair to become the leader, even amongst so notable a collection. In each chapter, Dr. Pearse reviews the chemistry and biological importance of the substances in question and then goes on to discuss critically the methods used for their demonstration and differentiation. The bibliographic references are numerous and appear to include most of the major contributions in each area. Pearse has omitted some references which appear fundamental, for example, the definitive experimental paper and review by Marcus Singer concerning the nature of acidic and basic staining of proteins (/. Biol. Chem. 75: 133, 1948; Internal. Rev. Cytol. I: 211, 1952). Likewise, the techniques which he has selected to give in detail represent his particular preferences, whereas numerous methods which are possibly equally satisfactory are barely mentioned. While Pearse's omissions in this respect are not serious, the usefulness of some methods which he has overlooked should not be lost sight of. Needless to say, in a field which is growing so rapidly and to which several journals are now entirely devoted, no book can long remain up-to-date.
7,499 citations
TL;DR: Histopathologies technic and practical histochemistry, Histopathologie techno-practical histochemistry and the role of nanofiltration in medicine and drug discovery and abuse are studied.
Abstract: Histopathologie technic and practical histochemistry , Histopathologie technic and practical histochemistry , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
3,259 citations
TL;DR: In this article, a detailed coverage of the many mechanisms birds have evolved to cope with seasonal variations in the availability of resources is provided, including hypophysial and other endocrine systems, the role of hormones in reproductive behavior, energy budgets in relation to reproduction, egg and clutch size, breeding seasons, circadian and ultradian rhythms and their control, sexual selection, and the pair bond.
Abstract: This book provides detailed coverage of the many mechanisms birds have evolved to cope with seasonal variations in the availability of resources. Readers will find discussion of the hypophysial and other endocrine systems, the role of hormones in reproductive behavior, energy budgets in relation to reproduction, egg and clutch size, breeding seasons, circadian and ultradian rhythms and their control, sexual selection, and the pair bond. Factors which influence avian survival rates are distinguished from the processes of population dynamics, and some constraints on evolutionary change are considered.
423 citations
TL;DR: Embryo attachment and implantation in the ewe have been examined with a view to elucidating the interrelationships of the trophoblast and the uterine epithelium, and defining accurately the time relationships of the various phenomena.
Abstract: Embryo attachment and implantation in the ewe have been examined with a view to (a) elucidating the interrelationships of the trophoblast and the uterine epithelium, and (b) defining accurately the time relationships of the various phenomena. Embryonic attachment occurred during the 15th day of pregnancy and cytological changes within the uterine caruncular epithelium that appeared on the following day and were completed within a week, resulted in the formation of plaques of multinucleate symplasm and the death of some maternal epithelial cells. High levels of acid phosphatase activity, considered to demonstrate the release of lysosomal hydrolases, were associated with the modification of the maternal epithelium and with the later trophoblastic invasion of the uterine stroma. Alkaline phosphatase activity present in the apical cell membranes of the opposing trophoblast and uterine epithelium is considered to be associated with carbohydrate metabolism and the production of trophoblastic fibrinoid. No evidence was obtained to support proposals that trophoblastic binucleate giant cells have a major role in modifying the uterine epithelium through their phagocytic activity or as a source of the cryptal epithelium. The cryptal epithelium during the first 6 weeks ofpregnancy appears to be derived from the symplasmic plaques of maternal epithelium.
225 citations