Breeding Phase Research Articles

Photoperiodic Regulation of Follicle-Stimulating Hormone Binding to Gonads and of Plasma Gonadotropin Concentrations in Indian Weaver Birds

Previous studies showed that changes of gonadal weight and of follicle-stimulating hormone (FSH) receptor number in response to fluctuations in natural environmental conditions are smaller in female than in male Indian weaver bird ( Ploceus philippinus). Therefore, we studied whether the response to artificial photoperiodic changes differs between the sexes. Birds were transferred to short-day (SD) photoperiods during the breeding phase (June). Other birds were subjected to long-day (LD) photoperiods during the nonbreeding phase (December). Exposure to SD for 10 weeks induced a marked testicular weight decrease. Similarly, FSH binding per unit testicular weight as well as per two testes decreased after SD exposure. The influence of photoperiodic manipulations on the ovarian weight was much smaller than that on the testicular weight. SD exposure did not alter FSH binding either per unit ovarian weight or per ovary. Plasma gonadotropin concentration significantly decreased in both sexes subjected to SD environment. On the other hand, exposure to LD significantly increased testicular weight. LD exposure slightly increased ovarian weight, but the increase was statistically not significant. FSH binding per unit testicular weight markedly increased 10 weeks after transfer to LD. The total FSH binding per two testes showed a parallel change with the testicular weight. However, there was no significant increase in FSH binding per unit ovarian weight during 10 weeks of LD exposure. Although LD exposure for 10 weeks significantly increased the total FSH binding per ovary, the rate of increase was much smaller than that in the testes. The plasma gonadotropin level in both sexes was increased by LD exposure. Scatchard plot analyses of FSH binding indicated that FSH binding changes were due to changes in binding site number. These results suggest that photoperiod regulates FSH receptor numbers particularly in the testis. Such an effect is manifested by marked changes in the testicular weight under different photoperiodic conditions in the subtropical bird.

A Comparative Study of Annual Changes in the Pineal Gland Morphology with Reference to the Influence of Melatonin on Testicular Activity in Tropical Birds, Psittacula cyanocephala and Ploceus philippinus

The aim of the present comparative investigation was to examine annual pineal cytological changes and the action of melatonin in relation to testicular activity in two wild tropical avian species. The findings revealed that in both blossomheaded parakeets (Psittacula cyanocephala) and Indian weaver birds (Ploceus philippinus) the pineal gland was inactive, with reduced karyometric values during the breeding season. A pinealoactive phase showing significantly increased pinealocyte nuclear diameter corresponded with the nonbreeding phase. Administration of melatonin (250 μg/100 g body wt) for 10 consecutive days caused significant involution of testes during the breeding phase, although it failed to alter reproductive activity during the nonbreeding phase. The results indicated that the pineal gland activity varied inversely with the seasonal testicular weight cycle and the antigonadal influence of melatonin appeared to be phase dependent, which corroborated the inverse temporal relationship of the pineal gland and male reproductive activity examined in the two tropical avian species.

Effect of altered thyroid and adrenal activity on the seasonal reproduction of the Indian palm squirrel, Funambulus pennanti

Thiouracil and metyrapone administered during the progression phase of the annual reproductive cycle inhibited gonadal development in the Indian palm squirrel, Funambulus pennanti. In a further experiment, these drugs led to normal gonadal regression during the late breeding phase. Thyroxine and corticosterone treatment, on the other hand, maintained the gonads continuously in breeding condition, unlike those of controls, which exhibited characteristic post-reproductive regression. Since hypofunction of the thyroid and adrenal glands had inhibitory effects on the initiation of seasonal gonadal growth, and hyperactivity affects post-reproductive regression, it is suggested that an optimal level of hormones is required for the normal breeding cycle in this subtropical mammal. The results are discussed in terms of an interrelationship between the seasonal thyroid, adrenal, and gonad cycles under natural conditions.

Daily activity at nests of the European bee-eaters (Merops apiaster)

During the breeding seasons 1985–1986, we studied the daily activity of adult bee-eaters by direct observations at four nests and by automatic recordings of three nests. During the digging and incubation phases, the adults' movements were scarce and concentrated during the morning, but in the chick-rearing stage they were high and reached a peak at noon and in the early afternoon. Among nests there were significant differences in the amount of adults' movements during all the breeding phases. The start of daily activity and the rate of the adults' movements to the nests were strongly related to air temperature.

Follicular dynamics and germinal bed activity during the annual ovarian cycle of the lizard, Calotes versicolor.

Changes in size frequency distribution of extrastromal follicles, atretric follicles (AF), and the number of oogonia, oocytes, and primordial follicles in the ovaries are studied in Calotes versicolor during its annual reproductive cycle. Extrastromal follicles were graded into stages I to VI based on their diemeter. Stage I (0.5-0.75 mm) follicles are found throughout the year. The recruitment of stage II (0.76-1 mm) and stage III (1.10-2 mm) follicles occurs during December and March, respectively. Follicles of stage I-III are found in greater number in May. Stage IV vitellogenic follicles (2.10-3 mm) are recruited in April. Advanced vitellogenic follicles (stage VI) are formed between May and August. From April to August, the ovaries of lizards contain vitellogenic follicles of stages IV or V or VI suggesting that once a set of follicles enters vitellogenic phase there is no recruitment of another set of vitellogenic follicles from previtellogenic follicles until the former ovulates. The presence of vitellogenic follicles and at least two sets of CL in July-August suggest that C. versicolor may oviposit at least three clutches of eggs per season. The clutch size in this lizard varies from a maximum 24 eggs in May to a minimum of 13 eggs in September. The previtellogenic AF are found throughout the year. Atresia is more prevalent in stage III suggesting that these follicles are more prone to become atretic. Interestingly, atresia of vitellogenic follicles occurs rarely. Each ovary in C. versicolor has two germinal beds. The germinal beds contain a greater number of oogonia (536-696), primary oocytes (40-71), and primordial follicles (32-55) during prebreeding and early breeding phases of the ovarian cycle. © 1993 Wiley-Liss, Inc.

The Ovarian Cycle in an Oviparous Gymnophione Amphibian, Ichthyophis beddomei (Peters)

The ovarian cycle in an oviparous gymnophione amphibian, Ichthyophis beddomei (Peters), was studied in captivity for 12 consecutive months from June, 1984 to May, 1985. A significant increase in the relative weight of the ovary, ovarian follicular diameter, recruitment of 70-80% of previtellogenic follicles (PVF) to vitellogenesis, and a significant decrease in the percentage of atretic follicles (AF) during August-November indicate that August-November might be the prebreeding phase of the ovarian cycle. The presence of the maximum number of the largest vitellogenic follicles (VF), the reduced number of AF, the minimum number of PVF, and presence of dividing oogonia during December-February suggest that the latter might be the breeding phase

Fat body ovarian relationship in the garden lizard, Calotes versicolor (Daud.).

Abdominal fat body mass of Calotes versicolor showed annual changes that were universal related to the changes in ovarian somatic (GSI) and hepatosomatic (HSI) indices. Fat bodies were absent in late breeding phase (June-August). Thirty day fatectomy (FBX) during prebreeding phase significantly reduced GSI, HSI, and total number of extrastromal follicles; also, recruitment of vitellogenic follicles was arrested and ateretic follicles increased. The FBX during postbreeding phase had no such effect, whereas in 30 day ovariectomised (OvX) lizards in prebreeding phase fat body mass significantly increased but HSI decreased. However, in lizards in prebreeding phase, E2 caused a significant decrease in fat body mass and an increase in HSI, while during the postbreeding phase there was a significant increase in HSI but the fat bodies were not affected. The above findings suggest that the development of the first clutch of vitellogenic follicles in the lizard utilises lipids stored in the fat bodies and that the growth of the subsequent clutches of vitellogenic follicles is met through the intake of food, which is abundant in the latter part of the breeding phase. The fat bodies are not needed for the growth of previtellogenic follicles. The fact that lipolytic action of E2 occurs only during the breeding phase suggests that responsiveness of the fat bodies to the steroid is related to the reproductive phase and that during postbreeding phase of the lizard they become refractory to E2.

Annual changes in the binding of follicle-stimulating hormone to gonads and plasma gonadotropin concentrations in Indian weaver birds inhabiting the subtropical zone

In birds, annual changes in gonadal weight are much more pronounced in the male than in the female. To analyze the mechanism inducing such a sex difference in the gonadal responsiveness to natural environmental conditions, we measured annual changes in the binding of follicle-stimulating hormone (FSH) to the gonads and the plasma gonadotropin concentration in adult Indian weaver birds inhabiting the subtropical zone. The binding of FSH was highly specific for mammalian FSHs and located primarily in the gonad. The testicular weight and FSH binding showed marked changes during the annual breeding cycle. The testicular weight was maximal in the breeding phase (June, 1987) and minimal in the nonbreeding phase (December, 1987). FSH binding per unit testicular weight was-greatest in the nonbreeding phase, while the total FSH binding per two testes was maximal in the breeding phase and minimal in the regressive phase (October, 1987). In contrast, the changes in the ovarian weight and FSH binding to the ovary were less pronounced than those in the testis. Although FSH binding per unit ovarian weight showed a peak in the nonbreeding phase; there was no significant change in the total FSH binding per ovary during the year, indicating the presence of a clear sex difference in the total FSH binding. Scatchard plot analyses of the binding suggested that the dissociation constant (Kd) ranged from 0.35 to 1.53 nM regardless of sex and season and that the changes in FSH binding were due to changes in the number of binding sites. Plasma FSH and luteinizing hormone (LH) levels markedly changed during the year in both sexes. Both FSH and LH levels were maximal in the breeding phase and minimal in the nonbreeding phase regardless of sex, although. the rate of change in either hormone tended to be greater in the male than in the female.

Antiphonal duetting and sex hormones in the tropical bush shrike Laniarius funebris (HARTLAUB)

We investigated changes in antiphonal duetting with phases of reproduction and circulating levels of luteinizing hormone, testosterone, and estradiol in slate-colored boubous ( Laniarius funebris) breeding in aviaries. Frequency of overall male singing did not vary with reproductive phase while frequencies of female singing and female vocal responses to male song were reduced during incubation and feeding of nestlings. This resulted in significant changes in frequency of duetting. Males sang the sexual song type M1 more often during courtship and nest building than during the nestlings phase. Their territorial song types M2 and M4 did not vary with breeding phase. Females were less responsive to M1 during incubation and to M2 during the nest building and nestlings than during the courtship phase. Plasma levels of luteinizing hormone and testosterone increased in males from the prebreeding to the courtship phase. While testosterone decreased already during nest building and remained low during subsequent phases of reproduction, luteinizing hormone decreased during incubation and feeding of nestlings. Female luteinizing hormone levels were highest during nest building. Female estradiol levels decreased from nest building to incubation and increased again during subsequent nest building. Female testosterone levels were low but not basal and did not vary with phase. Neither the overall male and female singing frequencies nor the frequencies of male song types were correlated with hormonal state. However, female participation in territorial duets M4 correlated positively with their testosterone levels. It is suggested that in this monogamous, duetting species with prolonged pairbonds behavioral cues between the mates are more important than the hormonal state in control of male and female singing.

Why are house sparrows predominantly monogamous? A test of hypotheses

Observational and experimental evidence collected in a 4-year study of house sparrows, Passer domesticus, was used to test hypotheses about the evolution of monogamy. Reproductive success increased for males and decreased for females with increasing harem size. This rejects hypotheses that state that monogamy is advantageous for both sexes. Only 9·6% of 197 control males were polygynous. However, after removal of 30 males, between 36·7 and 73·3% of potential bigamous males acquired an additional female; 43–65% of the experimental widows mated with already mated males while only 23·3% rejected polygynous bonds. This contradicts the prediction, derived from the hypothesis based upon the polygynythreshold model, that widowed females prefer to remate with unmated males. Of 86 males, 27·9%, more than the percentage of polygynous males, remated after a first breeding attempt with a female that had not bred in the colony that season. Hence, the limitation of the polygyny level cannot be explained by a lack of females. When nestboxes were put closer together, males held more of them, but they did not increase their harem size. This suggests that the limitation of nest sites is not a proximate determinant of monogamy. Resident females were very aggressive towards a caged female placed close to their nest. The way in which the aggression rate varied with breeding phase and intruder persistence favours the hypothesis that females protect their monogamous status. However, further direct tests are required to confirm that monogamy in this population is maintained by aggression between females.

Interrenal of a female gymnophione amphibian, Ichthyophis beddomei, during the annual reproductive cycle.

The interrenal (adrenal) of Ichthyophis beddomei lies on the ventral side of the kidney, distributed in four zones. It is separated from the renal tissue by a thin layer of connective tissue and contains both adrenocortical and chromaffin cells. Adrenocortical tissue constitutes a major portion of the interrenal islets; the chromaffin tissue consists of a few cells located at the peripheries of the interrenal islets. Histochemical studies demonstrate the presence of Δ5 3β-hydroxysteroid dehydrogenase, 17 β-hydroxysteroid dehydrogenase, glucose-6-phosphate dehydrogenase, succinate dehydrogenase, and sudanophilic lipids in the adrenocortical tissue, suggesting its steroidogenic potential. Annual histometric and histochemical studies show two peaks of interrenal activity: (1) during the breeding phase of the reproductive cycle (January and February) and (2) during the season of heavy monsoon rains (June and July) in the postbreeding phase.

Variation in Time and Energy Budgets of Breeding Wheatears

Abstract We examined the sources of variation in time allocation of males and females of the wheatear (Oenanthe oenanthe) on the island of Öland, South Sweden, throughout the breeding season. We quantified rates of prey capture attempts and specified foraging methods used. From respirometric measurements of basal metabolic rate and temperature-dependent metabolism on captive wheatears, and after having made certain assumptions abour the costs of different activities, we estimated the energy budgets of both sexes during the different reproductive phases. Males and females differed in their time allocation and foraging rates during prelaying, laying, and incubation, but not while feeding grown nestlings. During prelaying and laying, females foraged at higher rates than males; they also perched less often, gleaned more on the ground, and flew less. Although incubation was the least costly phase for females because of their low activity, high foraging rates yet indicated that this phase may represent an energetic bottleneck as a result of restrictions on foraging time. After incubation, females switched from foraging mostly on the ground during early breeding phases to hunting from elevated perches during later breeding phases. The shift in foraging behavior corresponds to the drastic changes in time allocation. Relatively high daily energy expenditures (DEE) by brooding females coupled with low foraging rates may explain the observed posthatching body mass losses. In both sexes, high required energy acquisition rates when feeding large nestlings indicate that parent wheatears then may encounter another energetic bottleneck. Postfledging was the least costly phase because, compared with the period of feeding nestlings, there were reduced thermostatic costs and a marked drop in flight time. Males and females had similar DEEs during prelaying, laying and nestling feeding, but females had lower needs during incubation. The elective components of energy budgets during nestling feeding, as well as the estimated sum of the elective components throughout the season, were 12% higher for males than for females. The elective components of the energy budgets varied more than the obligatory components (basal + thermoregulation), especially in females, and were more important in determining the variation of DEE throughout the breeding season. A validation study with doubly labeled water indicated that the energy budget model used was accurate enough for comparisons between sexes or breeding phases, but not for measuring individual variation.

Histophysiological Appraisal of the Texticular Functions in a Sub-Tropical Psittacine Bird, Psittacula krameri, in Relation to Annual Climatological Variables.

Annual testicular events in free-living Roseringed Parakeets were studied in relation to climatological variables over three consecutive years. Functional status of the testis was determined from paired testicular weight, seminiferous tubular diameter, spermatogenetic index, Leydig cell nuclear diameter and quantity of total testicular cholesterol. Based on these analysis the annual testicular cycle was divided into five different phases, namely regenerative or preparatory phase (May-August; resting spermatogonia present in the regressed tubules); progressive phase (Sept.-Dec.; recrudescence of gametogenesis occurs); prebreeding phase (Jan.-Feb.; spermiogenesis starts but at slow rate); breeding phase (March; active spermatogenesis occurs); and regressive phase (April-May; degenerative changes occur in the germ cells). A new generation of Leydig cells appeared during the preparatory phase and matured during the progressive phase. Signs of Leydig cell hyperactivity were detectable till the end of the breeding phase. However, statistical analysis failed to identify any environmental component that may have induced seasonal testicular maturation in free-living Roseringed parakeets.

Parental Investment by the Sexes in the Herring Gull: The Use of Energy Reserves during Early Breeding

A sample of culled birds was used to determine weight change and size of endogenous nutrient reserves in male and female Herring Gulls Larus argentatus during the period from colony occupation to late incubation. Both sexes showed considerable variation in body condition according to breeding phase. The most striking difference between the sexes was found in lipid contents prior to laying. Whereas males tended to deplete endogenous fat, females gained fat. There was no marked change in protein reserves in either sex. It is concluded that males meet maintenance costs during courtship feeding by using a great deal of their endogenous fat while saving the proteins. This is done in favour of the body condition of the laying female, males thus equalizing the initial parental investment of the two sexes. Both sexes regained energy reserves during incubation, being in equal physiological condition when the

Reproductive toxicity of boric acid in Swiss (CD-1) mice: Assessment using the continuous breeding protocol

The potential reproductive toxicity of boric acid (BORA) in CD-1 mice (Swiss) was evaluated using the Reproductive Assessment by Continuous Breeding (RACB) Protocol. BORA was administered in the feed for 27 weeks to male and female Swiss (CD-1) mice at concentrations of 0, 1000, 4500, or 9000 ppm. Estimated doses, based on feed consumption and body weight, averaged 152, 636, and 1262 mg/kg body wt during Week 1 for males for 1000, 4500, and 9000 ppm, respectively. During 14 weeks of cohabitation, fertility of F 0 mice was partially reduced at 4500 ppm and totally eliminated at 9000 ppm. No litters, dead or alive, were produced by 9000 ppm cohabited pairs. Among the litters born at 4500 ppm, live litter size and body weight were significantly reduced. A crossover mating trial of control and 4500 ppm groups confirmed the male as the affected sex, with fertility rates and the mating index significantly lower in the 4500 male × 0 ppm female group. At necropsy, after 27 weeks of BORA exposure, dose-related changes were present in F 0 males for reduced body and reproductive organ weights, increased incidence of abnormal sperm, decreased sperm concentration and motility, and seminiferous tubule degeneration. In the 4500 ppm females, dietary BORA for 27 weeks caused significantly decreased weights of kidney/adrenals and livers; kidney/adrenal weight was also reduced in 4500 ppm males. The last litters of the control and 1000 ppm females, born in the 14-week breeding phase, were reared to 74 days of age and then mated in nonsibling pairs within treatment groups. These F 1 mice had normal fertility, but the adjusted mean body weight of F 2 pups was decreased. These data establish the reproductive toxicity of BORA in CD-1 mice and demonstrate that the male is the most sensitive sex.

Physical characteristics of the blood plasma of Labeo ruddi and Labeo rosae (pisces: cyprinidae)

1. 1. The physical composition of blood plasma of Labeo ruddi and Labeo rosae males were determined during the breeding and post breeding phases. 2. 2. The mean values for most blood electrolytes, pH and osmolality of the two species showed the same variation as was found for other cyprinids. 3. 3. The ability to handle stress may be reflected in the presence of certain electrolytes in the blood and efforts are made to relate differences in the concentration of these parameters to interspecies differences between L. ruddi and L. rosae.

Effects of corticosterone, metapyrone, and ACTH on testicular function at different stages of the breeding cycle in migratory redheaded bunting, Emberiza bruniceps

To study the seasonal reproductive responses, corticosterone (0.2 and 2 μg/day), metapyrone (0.6 mg/day), and ACTH (0.25 IU/day) were administered in male redheaded bunting, Emberiza bruniceps, during different phases of the annual gonadal cycle. All of the three treatments inhibited gonadal growth during the preparatory phase, suggesting that during the early stage of annual gonadal growth, an optimum level of the hormones of pituitary-adrenal axis is essential. In the progressive and breeding phase, while corticosterone administration had no effect, metapyrone inhibited the annual gonadal development, suggesting the necessity of increasing or increased adrenal steroid hormone during this phase. In the regressive phase, while corticosterone enhanced the rate of gonadal regression, metapyrone treatment did not allow the gonad to regress. Further, ACTH administration induced full breeding condition in the regressing gonad. It is suggested that while a higher level of adrenal steroids and a low ACTH (by exogenous corticosterone) may enhance the testicular regression, moderate levels of ACTH (caused by exogenous metapyrone) did not allow regression and increased ACTH levels (by exogenous ACTH) caused full development of the regressing gonad. Thus the sensitivity of the neuroendocrine-gonadal axis not only varies in response to photoperiod, but the reproductive system also responds differently to pharmacological administration of the above three hormones and drugs during different phases of the breeding cycle.

Reproductive toxicity of 2,2-bis(bromomethyl)-1,3-propanediol in a continuous breeding protocol in Swiss (CD-1) mice

The effect of 2,2-bis(bromomethyl)-1,3-propanediol (BMP) on reproduction in Swiss CD-1 mice was evaluated by use of a continuous breeding protocol. BMP was administered in the feed at 0.1, 0.2, and 0.4% concentrations. Both male and female F 0 mice (20 pairs per treatment group, 40 pairs of control animals) were dosed 7 days prior to and during a 98-day cohabitation period. Although the fertility index was unchanged in the high-dose group, BMP exposure significantly decreased the numbers of litters per pair, pups born alive per litter, and pup weight when adjusted for litter size. Crossover mating between treated and control F 0 animals indicated a specific effect only on female reproductive capacity. At the highest dose, BMP caused a body weight decrease in the F 0 animals of both sexes with no effect on relative organ weights. Sperm concentration, motility, morphology, and estrual cyclicity were unaffected by BMP exposure. Histopathology in the F 0 animals revealed specific kidney lesions in both sexes; males were more sensitive than females. The last litter born in the 98-day breeding phase was reared to age 74 days and then mated to nonsiblings of the same treatment group. The effect of high-dose BMP exposure on F 1 fertility, body and organ weights, sperm parameters, and estrual cyclicity was the same as that for the F 0 animals, with the exception of the lack of renal lesions seen in the F 1 females. These data show that BMP impaired fertility in female mice in both generations in the absence of an effect on reproductive organ weights and estrual cyclicity.

Courtship Feeding and Clutch Size in Red-Backed Shrikes (Lanius collurio)

Previous articleNext article No AccessNotes and CommentsCourtship Feeding and Clutch Size in Red-Backed Shrikes (Lanius collurio)Allan CarlsonAllan Carlson Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 133, Number 3Mar., 1989 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284928 Views: 10Total views on this site Citations: 21Citations are reported from Crossref Copyright 1989 The University of ChicagoPDF download Crossref reports the following articles citing this article:Ishani Mukherjee, Anuradha Bhat Temporal Patterns in Interactions Across Same- and Mixed-Sex Wild Zebrafish Dyads, Zebrafish 18, no.55 (Oct 2021): 307–315.https://doi.org/10.1089/zeb.2021.0012Alessandra Costanzo, Nicola Tommasi, Andrea Galimberti, Giorgia C. 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Seasonal ovarian cycle in a wild Indian Tree Pie Dendrocitta Vagabunda.

The female reproductive cycle was investigated in the Indian Tree Pie (Dendrocitta vagabunda) by studying the ovary once a month throughout the year. The ovarian activity showed a distinct annual cycle consisting of four phases: nonbreeding (August to January); progressive (February and March); breeding (April and May); and regression (June and July). The weight of the ovary and diameter of the largest follicle were smallest during the nonbreeding phase, partially increased during the progressive phase, peaked during breeding and decreased thereafter. The primordial and small developing follicles were present in the ovary throughout the year but large developing follicles appeared during April, May and June. Yolky and post-ovulatory follicles were found only during the breeding phase. The population of primordial follicles declined, followed by a rise in the population of small and large developing follicles with the appearance of yolky follicles, during the breeding phase as compared to those of other phases of the cycle. Cholesterol and ascorbic acid concentrations were highest during the nonbreeding phase, slightly declined during the progressive phase, became lowest during breeding and began to rise subsequently. But acid phosphatase, alkaline phosphatase, sialic acid, glycogen, RNA and protein levels were reversely altered. The findings indicate that the ovarian folliculogenesis as well as steroidal activity vary simultaneously with a peak in May during the breeding phase of the seasonal sexual cycle of the tree pie.