Characterization of the external female genitalia of six species of Triatominae (Hemiptera: Reduviidade) by scanning electron microscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Follicle profile and plasma gonadotropin concentration in pubertal female ponies

Twelve female ponies were examined daily for 30 days and classified as ovulating (OV; N = 6; 197 ± 6 kg) or prepubertal (PP; N = 6; 196 ± 9 kg). Follicles were detected by ultrasound and gonadotropins quantified by radioimmunoassay. The mean diameter of the largest follicles was significantly larger in OV (38 ± 1 mm) than in PP (26 ± 2 mm) but there was no difference between groups in the size of the second largest follicle. There were more small follicles (<24 mm) in the PP than in the OV group, but PP fillies had a smaller number of follicles >29 mm than the OV fillies. Follicle-stimulating hormone (FSH) levels did not differ between groups but PP fillies had lower luteinizing hormone (LH) peak (8 ± 1 ng/ml) and basal (4 ± 0.5 ng/ml) levels, lower peak magnitude (2 ± 0.2 ng/ml) and period average (5 ± 0.6 ng/ml) than OV fillies (32 ± 4.5, 8 ± 1.2, 17.1 ± 6, and 15 ± 2.3 ng/ml, respectively). The PP group, in contrast to the OV group, showed no relationship between FSH surge and follicle wave emergence. We conclude that an LH concentration higher than 8 ng/ml is needed for follicle growth to a preovulatory size. Wave emergence and FSH secretion seem to be independent events, probably due to an inhibitory neural system in these PP animals. PP fillies may provide a physiological model for the study of follicle wave emergence which apparently does not depend on gonadotropin levels.

Female monopolization and paternity assurance in South American crickets (Orthoptera, Grylloidea): mating plugs, extra claspers and forced copulation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive physiology, and physical and sexual development of female offspring born to diabetic dams

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Handling of female pacas (Agouti paca, Linnaeus, 1766) for ultrasound pregnancy detection

A paca é um roedor sul-americano cujo manejo, tranqüilização ou anestesia oferece um grande campo de pesquisa devido aos poucos artigos existentes. Doze pacas fêmeas adultas foram utilizadas, mantidas separadas em seis baias, sendo capturadas com um puçá de polipropileno e levadas a uma sala na qual se realizava a tricotomia abdominal. Após, os animais eram colocados em uma gaiola de ferro de compressão lateral. A sessão de ultra-sonografia era realizada em modo B com um transdutor setorial eletrônico de 5,0 e 7,5 MHz. Para a diminuição do estresse causado pelos procedimentos, a tranqüilização das fêmeas era realizada com diazepam e maleato de midazolam por via oral. Ambos demonstraram-se efetivos na tranqüilização das pacas previamente e durante as sessões, sendo que o maleato de midazolam proporcionou um melhor manejo dos animais.

Sex Determination and Female Reproductive Development in the GenuSchistosoma: A Review

Os parasitas do gênero Schistosoma situam-se entre os primeiros metazoários que desenvolveram sexos separados, determinado cromossomicamente no ovo fertilizado. Apesar da ocorrência de cromossomos sexuais específicos, as fêmeas de Schistosoma não atingem a maturidade somática e sexual sem a presença dos machos. Na verdade, um dos aspectos mais controversos e, ao mesmo tempo, mais fascinantes, envolvendo o desenvolvimento sexual das fêmeas está em se desvendar a natureza do estímulo que controla e mantém tal processo. Muito embora a natureza do estímulo (físico ou químico) seja motivo de controvérsia, concordam os mais diferentes autores que o acasalamento é um requisito indispensável para que ocorra a maturação e migração das fêmeas para o sítio definitivo de permanência no sistema vascular do hospedeiro vertebrado. Admite-se, ainda, que o estímulo não é espécie-específico e, em alguns casos, nem mesmo gênero-específico. Não obstante a existência de um número considerável de artigos dedicados ao tema, não há um consenso sobre o processo (ou processos) que controla(m) o encontro de machos e fêmeas no sistema circulatório do hospedeiro vertebrado, bem como está por ser determinada a natureza do estímulo, oriundo dos machos, que controla e mantém o desenvolvimento somático e sexual das fêmeas. Ao longo dos anos os machos de Schistosoma têm sido considerados, por vezes pejorativamente, os irmãos, os músculos ou o fígado das fêmeas. em síntese, resta saber se a natureza do estímulo responsável pelo desenvolvimento das fêmas envolve a transferência de hormônios, nutrientes, a mera estimulação tátil ou a combinação de dois ou mais desses fatores

Ingestive behavior and performance of female lambs grazing on Marandu palisadegrass under different stocking rates

The ingestive behavior and performance of female lambs grazing on Marandu pasture submitted to different stocking rates during the rainy and transition season were evaluated. The experimental area with 4,500 m² was divided into 45 paddocks of 100 m². Twenty-seven Santa Ines female lambs (purebred) with 4 months age and 22 kg of initial body weight were distributed in a completely randomized design, with nine replicates. Lambs were divided into 9 groups with the same initial weight and submitted to three stocking rates: 2, 3 and 4 lambs/paddock, which corresponded to 40, 60 and 80 lambs/ha, respectively. Each group of animals had a module of five paddocks, managed on intermittent grazing system, with 7 days of occupation and 28 d of rest. Increase on time grazing and reduction on time ruminating and resting were observed as stocking rates increased. There was 14% raise in time grazing and 41% decline on time resting by lambs subjected to the highest stocking rate compared with those in the lower stocking rate. The number of animals/ha promoted linear effect on average daily gain, which was higher for animals in the lowest stocking rate of 90 g/d. For gain per area, the best result was obtained with 60 animals/ha featuring an average value of 426 kg/ha.

Pharmacological evidence for beta(2)-adrenoceptor in right atria from stressed female rats

The purpose of the present study was to demonstrate a physiological response to TA2005, a potent beta(2)-adrenoceptor (beta(2)-AR) selective agonist, in right atria isolated from stressed female rats under the influence of the estrous cycle. We obtained concentration-response curves to the agonist in the presence and in the absence of selective antagonists in right atria isolated from female rats submitted to three daily foot-shock sessions (30 min duration, 120 pulses of 1.0 mA, 1.0 s, applied at random intervals of 5-25 s) and sacrificed at estrus or diestrus. Our results showed that the pD(2), values of TA2005 were not influenced by estrous cycle phase or foot-shock stress. However, in right atria from stressed rats sacrificed during diestrus, the concentration-response curve to TA2005 was biphasic, with a response being obtained at concentrations of 0.1 nM, whereas during estrus no response was observed at doses lower than 3 nM. ICI118,551, a beta(2)-AR antagonist, abolished the response to nanomolar concentrations of TA2005 in right atria from stressed rats at diestrus, with no changes in a,agonist pot values in right atria from control rats (7.47 +/- 0.09, p > 0.05) but a 3-fold decrease in pD(2), values of TA2005 in right atria from foot shock stressed rats (7.90 +/- 0.07, p less than or equal to 0.05). Concentration-response curves to TA2005 in the presence of ICI118,551 were best fitted by a one-site model equation. The beta(1)-AR antagonist, CGP20712A, shifted to the right only the second part of the concentration-response curves to the agonist, unmasking the putative Pz-AR-mediated response to the agonist in tissues isolated from stressed rats at diestrus. Under this condition, concentration-response curves to the agonist were best fitted by a two-site model equation. pot and maximum response of TA2005 interaction with beta(1)- and putative Pz-adrenoceptor components were calculated. Schild analyses gave a pK(B) value for CGP20712A that was typical for the interaction with beta(1)-AR in each experimental group. pK(B), values for ICI118,551 could not be obtained in stressed rats sacrificed at diestrus since Schild plot slopes were lower than 1.0. In right atria from control rats, ICI118,551 pK(B), values were similar to reported values for the interaction of the antagonist with beta(1)-AR. These results confirm that a heterogenous PAR population mediating the chronotropic response to catecholamines can be demonstrated in right atria from foot shock stressed female rats sacrificed at diestrus. The stress-induced response seems to be mediated by the beta(2)-AR subtype. Right atria from rats sacrificed during estrus are protected against stress-induced alterations on the homogeneity of PAR population.

Protandry and female size-fecundity variation in the tropical butterfly Brassolis sophorae

Protandry (the emergence of males before fe males) is currently explained either as a mating strategy to maximize number of matings in the males, or a way to minimize pre-reproductive mortality in females, Models of protandry have generally ignored variation in female quality (reproductive potential). We recorded the sex ratio, female body mass, wing length and potential fecundity (number and mass of eggs) of the tropical butterfly Brassolis sophorae through the emergence period. Temporal variation in female size and fecundity correlated with male potential for acquiring mates. Females from the end of the emergence period showed lower fecundity and size. Males emerging before and close to the median date of the female emergence period had greater mating opportunities. Males emerging either very early or late were penalized by few mating opportunities, or by encounters with small: low-quality females, respectively.

Testosterone stimulates growth and secretory activity of the female prostate in the adult gerbil (Meriones unguiculatus)

The prostate of the female gerbil (Meriones unguiculatus) is similar to the human female prostate (Skene gland) and, despite its reduced size, it is functional and shows secretory activity. However, virtually nothing is known about its physiological regulation. This study was thus undertaken to evaluate the behavior of the gerbil female prostate in a hyperandrogenic condition. Adult females received subcutaneous injections of testosterone cypionate (1 mg/kg body weight every 48 h) up to 21 days. Circulating levels of testosterone and estradiol were monitored, and the prostate and ovaries subjected to structural and immunocytochemical analyses. The treatment resulted in sustained high levels of circulating testosterone, and caused a transient increase in estradiol. There was an increase in epithelial cell proliferation accompanied by significant reorganization of the epithelium and an apparent reduction in secretory activity, followed by a progressive increase in luminal volume density and accumulation of secretory products. Immunocytochemistry identified the expression of androgen receptor and a prostate-specific antigen (PSA)-related antigen in prostatic epithelial cells. A circulating PSA-related antigen was also found, and its concentration showed strong negative correlation with circulating estrogen. Epithelial dysplasia was detected in the prostate of treated females. Analysis of the ovaries showed the occurrence of a polycystic condition and stromal cell hyperplasia. The results indicate that testosterone has a stimulatory effect on the female prostate, inducing epithelial cell proliferation, differentiation, secretory activity, and dysplasia. The results also suggest that prostatic growth and activity, polycystic ovaries, and ovarian stromal cell hyperplasia are related to a hyperandrogenic condition in females.

Central interaction between atrial natriuretic peptide and angiotensin II in the control of sodium intake and excretion in female rats

We investigated the effects of estrogen on sodium intake and excretion induced by angiotensin II (ANG II), atrial natriuretic peptide (ANP) or ANG II plus ANP injected into the median preoptic nucleus (MnPO). Female Holtzman rats weighing 250-300 g were used. Sodium ingestion and excretion 120 min after the injection of 0.5 mu l of 0.15 M NaCl into the MnPO were 0.3 +/- 0.1 ml (N = 12) and 29 +/- 7 mu Eq in intact rats, 0.5 +/- 0.2 ml (N = 10) and 27 +/- 6 mu Eq in ovariectomized rats, and 0.2 +/- 0.08 (N = 11) and 38 +/- 8 mu Eq in estrogen-treated ovariectomized (50 mu g/day for 21 days) rats, respectively. ANG II (21 mu M) injection in intact, ovariectomized, and estrogen-treated ovariectomized rats increased sodium intake (3.8 +/- 0.4, 1.8 +/- 0.3 and 1.2 +/- 0.2 ml/120 min, respectively) (N = 11) and increased sodium excretion (166 +/- 18, 82 +/- 22 and 86 +/- 12 mu Eq/120 min, respectively) (N = 11). ANP (65 mu M) injection in intact (N = 11), ovariectomized(N = 10)and estrogen-treated ovariectomized (N = 10) rats increased sodium intake (1.4 +/- 0.2, 1.8 +/- 0.3, and 1.7 +/- 0.3 ml/120 min, respectively) and sodium excretion (178 +/- 19, 187 +/- 9, and 232 +/- 29 mu Eq/120 min, respectively). Concomitant injection of ANG II and ANP into the MnPO of intact (N = 12), ovariectomized (N = 10) and estrogentreated ovariectomized (N = 10) rats caused smaller effects than those produced by each peptide given alone: 1.3 +/- 0.2, 0.9 +/- 0.2 and 0.3 +/- 0.1 ml/120 min for sodium intake, respectively, and 86 +/- 9, 58 +/- 7, and 22 +/- 4 mu Eq/120 min for sodium excretion, respectively. Taken together, these results demonstrate that there is an antagonistic interaction of ANP and ANG II on sodium intake and excretion, and that reproductive hormones affect this interaction.

Reproductive aspects in female rats exposed prenatally to hydrocortisone

We investigated the effects of hydrocortisone during the prenatal period and its later repercussion on reproductive aspects of female rats. Pregnant rats were treated (s.c.) with hydrocortisone acetate, at 1.5 mg/day on the 17th, 18th, and 19th days of pregnancy. Although the present study was not intended to identify mechanisms of toxicity, the treatment with hydrocortisone in the last period of pregnancy presented no signs of toxicity. The efficacy of the hydrocortisone in reducing the adrenal wet mass and plasma corticosterone levels immediately after delivery in both the treated mothers and in respective pups at birth may indicate impairment of the hypothalamus-pituitary-adrenal axis. In addition, the treatment with hydrocortisone did not interfere in the development of the female descendants until puberty. However, it affected the estrous cycle and fertility, Probably, the prenatal exposure to corticosteroids had altered at least partially the hypothalamus-pituitary-gonadal axis, resulting in the damages observed in adult life. These results indicate that the use of the hydrocortisone at a dose that apparently does not endanger the neonate led to undesirable effects in the adult reproductive phase, resulting in later deleterious alteration of the reproductive physiology in female rats. (C) 2004 Elsevier B.V. All rights reserved.