Aedes aegypti: egg morphology and embryonic development.

BACKGROUND: The diseases for which Aedes aegypti is a vector are worrisome. The high vector competence of this mosquito, as well as its anthropophilia and ability to adapt to the urban environment, allows it to exploit many habitats, making its prevention an arduous task. Despite current disease control measures focused on the mosquito, the effectiveness in containing its dispersion still requires improvement; thus greater knowledge about this insect is fundamental. METHODS: Aedes aegypti egg morphology and embryonic development were analyzed from eggs of the insectary of the Institute of Biomedical Sciences of the University of São Paulo. Optical (light and confocal) and electronic (transmission and scanning) microscopy were used to analyze the morphological and ultrastructural features of the eggs. Embryos were observed in the initial (0-20.5 h after egg-laying), intermediate (20.6-40.1 h after egg-laying), and final (40.2-61.6 h) stages of development, and kept at a temperature of 28 °C ± 1 °C until collection for processing. RESULTS: Eggs of Ae. aegypti were whitish at the time of oviposition, and then quickly became black. The egg length was 581.45 ± 39.73 µm and the width was 175.36 ± 11.59. Access to the embryo was difficult due to the egg morphology, point of embryonic development, and difficult permeability of the exochorion (mainly in fixation). Only about 5% of the collected eggs were successfully processed. In the initial stage of embryonic development, characteristics suggestive of intense cellular activity were found. In the intermediate stage, the beginning of the segmentation process was evident. In the final phase, it was possible to differentiate the cephalic region and the thoracic and abdominal segments. CONCLUSION: The chorion was found to be an important protective barrier and a limiting factor for the evaluation of the embryos and mosquito embryonic cells, indicating that further studies need to be carried out to identify the reason that this occurs.

Increased size and energy reserves in diapausing eggs of temperate Aedes aegypti populations.

Many insects overwinter in diapause, a pre-programmed anticipated response to unfavorable environmental conditions, often induced by a short-day photoperiod. Diapause involves morphological changes and increased energy stores required for metabolic demands during winter. In diapausing mosquito eggs, the accumulation of lipids plays an important role, because these molecules are the primary fuel consumed during embryogenesis and pharate larvae metabolism, and have a key role in egg desiccation resistance. The supposed inability of the mosquito Aedes aegypti to lay diapausing eggs has been recently challenged by a study on a temperate population, which showed that the inhibition of egg hatching in response to short days is possible in this species. Thus, the aim of the present study was to assess the effects of parental photoperiod on embryonic diapause-related traits, such as the triglyceride content and size of eggs laid, of two populations whose localities of origin differ in their winter length. Two colonies were maintained for each population: one under a Short-Day Photoperiod (SD: 10 h:14 h - Light:Dark) and the other under a Long-Day Photoperiod (LD: 14 h:10 h - Light:Dark). The eggs obtained from each combination of population and light treatment were used for size measurement (length, width and volume) and for the quantification of triglyceride content. Egg size showed differences between photoperiod treatments, with larger width and volume in eggs from the SD treatment. Remarkably, eggs from the SD treatment accumulated twice as many triglycerides as those from the LD treatment. Also, the eggs derived from the population having the longer winter accumulated larger amounts of triglycerides. The higher lipid content is probably contributing to a better survival during the cold season in both populations. The photoperiod-induced response in egg size and amount of triglycerides observed in this study support the hypothesis that the Ae. aegypti populations studied are able to lay diapausing eggs, a fact that provides physiological bases for the further expansion of this species to colder regions.

Presence of the matrix metalloproteinases during the migration of the primordial germ cells in zebrafish gonadal ridge.

In vertebrates, the primordial germ cells (PGCs) differentiate from extragonadal regions, migrating to gonadal ridge during the embryonic development. However, recent studies in mammals indicate that the PGCs originate from the epiblast and subsequently migrate into the yolk sac. Cell and molecular bases involved in routes during the migration of these cells are still not well understood. Thus, in an attempt to evaluate the participation of matrix metalloproteinases (MMPs) during the gonadal primordium formation in Danio rerio (zebrafish), the route of migration of PGCs was analyzed. In zebrafish, during the migration of the PGCs to the forming gonad, they bind by cytoplasmic processes to the extracellular matrix and migrate through amoeboid movements until they reach the gonadal ridge. During the epiboly, MMPs were not detected. However, after organogenesis, three MMP types were expressed in the somatic cells that were located ahead of the PGCs in the migration route. This expression was maintained throughout the mesentery and was not detected in the PGCs. Upon reaching the gonadal ridge, the PGCs and somatic cells express MMPs and epithelium begins to be formed. After the formation of the basement membrane, the germinal epithelium is delineated by the somatic cells, which remodeling the extracellular matrix. So, a PGC organization occurs through the tissue, forming the gonadal primordium. Concomitantly, granulocytes expressing different MMPs are present. This data in exposing the role of MMPs during the PGC migration to the forming gonad, may point a new way in understanding the reproductive biology of the vertebrates in general.

Total electrolyte balance for laying hens / Balanço eletrolítico total para galinhas poedeiras

This study was done to determine the best value of the total electrolyte balance (BET) concerning the variables of performance and egg quality of the laying hens. We investigated 240 Hy-Line Brown laying hens, of 30 to 46 weeks of age, adopting the completely randomized experimental design, which included five treatments (1000, 1250, 1500, 1750 and 2000 μeq / kg), 8 repetitions and 6 birds per unit. The performance and quality of the birds eggs were evaluated in the different treatments. The results were subjected to the analysis of variance and, wherever significant effect was noted, the regression equations were estimated, taking into account the electrolyte balance (μeq / kg) as a concomitant variable, applying the SAS statistical program (2001). The consumption, production, and feed conversion variables by dozen eggs, final bird weight, egg density, yolk color, Haugh Unit, albumen weight, shell weight, and egg weight, were found to be unaffected by the experimental BET values. The values of the feed conversion per egg mass, yolk weight and uniformity were affected by the different BETs. The electrolyte balance values showing minimum feed conversion, higher yolk weight, and better uniformity were, respectively, BET = 1400, 1330, and 1250 in μeq / kg of loads at the different temperatures. From the regression equations, the value indicated was BET=1390 for the 30- to 46-week-old laying hens. The electrolyte balance of the diet was found to affect the laying hens in terms of performance and egg quality.(AU)

Objetivou-se avaliar o melhor valor de balanço eletrolítico total (BET) para as variáveis de desempenho e qualidade dos ovos de galinhas poedeiras. Foram utilizadas 240 galinhas poedeiras da linhagem HyLine Brown, durante o período de 30 a 46 semanas de idade, distribuídos em um delineamento inteiramente casualizado, com cinco tratamentos (1000, 1250, 1500, 1750 e 2000 μeq/kg), oito repetições e seis aves por unidade experimental. Foram avaliados o desempenho e a qualidade dos ovos das aves com os diferentes tratamentos. Foi realizada análise de variância e, no caso de efeito significativo, foram estimadas equações de regressão considerando como variável concomitante o balanço eletrolítico (μeq/kg), usando o programa estatístico SAS (2001). As variáveis de consumo, produção, conversão alimentar por dúzia de ovos, peso final das aves, densidade do ovo, coloração da gema, Unidade Haugh, peso do albúmen, peso da casca e peso do ovo, não foram afetados pelos BET experimentais. Os valores de conversão alimentar por massa de ovos, peso de gema e uniformidade foram influenciados pelos diferentes BET. Os valores de balanço eletrolítico que propiciaram conversão alimentar mínima, melhor peso de gema e melhor uniformidade foram, respectivamente: BET=1400, BET = 1330 e BET = 1250 em μeq/kg de cargas nas rações. Conforme as equações de regressão indica-se o valor de BET de 1390 para poedeiras de 30 a 46 semanas de idade. O balanço eletrolítico da dieta afeta o desempenho e a qualidade dos ovos de galinhas poedeiras.(AU)

First description of the immature stages of Fannia sabroskyi Seago, 1954 (Insecta, Diptera, Fanniidae).

Egg, larvae and the puparium of Fannia sabroskyi Seago, 1954 (Diptera, Fanniidae) are described and illustrated for the first time. The following structures have been documented: pseudocephalon, antennal complex, maxillary palpus, facial mask, anterior spiracle, cephaloskeleton structures, thoracic and abdominal processes, anal division, and posterior spiracle. Due to its necrophagous habit, this species may be of potential forensic importance for estimating the postmortem interval in criminal investigations. The information presented herein may be useful to distinguish the immature forms of Fannia species and to supplement the database for identification of Neotropical species of Fanniidae. In addition, it is also important for evolutionary and phylogenetic studies.

Embryonic and early larval development of two marine angelfish, Centropyge bicolor and Centropyge bispinosa.

Marine angelfish (family: Pomacanthidae) are among the most sought-after fish species in the saltwater aquarium trade. However, there is a lack of information in the literature on their early ontogeny. The objective of this study was to describe the embryonic and early larval development of two dwarf angelfish, the bicolour angelfish, Centropyge bicolor and the coral beauty angelfish, Centropyge bispinosa. The eggs of these two species were obtained from spontaneous spawning of the broodstock fish in captivity and incubated at 26.0 ± 0.2°C throughout the study. Fertilized eggs (n = 15) of both species are transparent, pelagic and spherical; the mean diameters of the eggs were measured at 703.6 ± 7.8 µm for C. bicolor and 627.6 ± 7.8 µm for C. bispinosa. The eggs of both species possessed a narrow perivitelline space, smooth and thin chorion, a homogenous and non-segmented yolk as well as a single oil globule. Overall, the observed embryonic development pattern of C. bicolor and C. bispinosa was very similar, and the main difference was the embryonic pigmentation pattern, which only became evident close to hatching. Larvae of both species started hatching at 13 h 30 min after fertilization, and the larval characteristics of both species also showed high levels of similarities. However, the mouth opening time for C. bicolor was 72 h after hatching (AH) and 96 AH for C. bispinosa. In general, the observed early ontogeny of C. bicolor and C. bispinosa also resembled that of other Centropyge species documented in the literature.

Criteria for identification of Schistosoma mansoni eggs in faecal sediments prepared with the Helmintex method and stained by ninhydrin.

Helmintex is a sensitive method used for detecting Schistosoma mansoni eggs. Here, we describe the observed frequency of six proposed criteria associated with the identification of S. mansoni eggs prepared with the Helmintex method and stained with ninhydrin. The efficacy of these criteria in classifying S. mansoni eggs when applied in various combinations was also examined. Nine observers registered the presence or absence of 6 different criteria in 100 eggs using a microscope at 100x magnification. Ninhydrin purple, which was frequently observed, was the criterion associated with the lowest inter-observer variability. At least three criteria were associated with a significantly better performance in egg identification. In conclusion, ninhydrin staining and a combination of criteria are recommended for microscope examination of faecal sediments.

Ancient parasitic DNA reveals Toxascaris leonina presence in Final Pleistocene of South America.

Parasitological analysis of coprolites has allowed exploring ecological relationships in ancient times. Ancient DNA analysis contributes to the identification of coprolites and their parasites. Pleistocene mammalian carnivore coprolites were recovered from paleontological and archaeological site Peñas de las Trampas 1.1 in the southern Puna of Argentina. With the aim of exploring ancient ecological relationships, parasitological analysis was performed to one of them, dated to 16 573-17 002 calibrated years BP, with 95.4% probability. Parasite eggs attributed to Toxascaris sp. by morphological characters were isolated. DNA of coprolite and eggs was extracted to molecular identification. Ancient mitochondrial DNA analysis confirmed the zoological origin of the coprolite as Puma concolor and that of parasite eggs as Toxascaris leonina. This is the oldest molecular parasite record worldwide, and it supports the presence of this parasite since the Pleistocene in America. These findings have implications for the biogeographic history of parasites and for the natural history of the region.

Morphological description of the immature stages of Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae).

In the dipteran genus Hermetia, only 6 of the 78 valid species have documented immature stages: H. albitarsis Fabricius, 1805, H. aurata Bellardi, 1859, H. concinna Williston, 1900, H. illucens (Linnaeus, 1758), H. panamensis Greene, 1940 and H. pulchra Weidemann, 1830. In particular, H. illucens stands out due to its reported applicability for forensic, medical and economic purposes. Here, we described the morphology of eggs and immature stages of this species, with a view to detecting differences between instars and in the pupal stage, which should eventually help properly identifying larval age. We utilized both optical and scanning electron microscopy tools. The eggs are elliptical and elongated, and color varies from cream white to yellowish. The larvae are apodal, hemichephalic and holopneustic, flattened dorso-ventrally and may be recognized by the head elongated, dorsal and ventral chaetotaxy of the cephalic capsule, thoracic and abdominal segments, and the morphology of the anterior and posterior spiracles. The pupae are adecticous and coarctate, tegument dark brown and pruinescence varying from brown to golden. The overall morphology across instars is similar, but marked variations were observed in the shape of the antennal articuli and the shape of the setae (first instar compared to the others). Our results supplement the biological information on Hermetia illucens and should aid the proper identification and aging of juveniles in the field, as a way to minimize errors in the calculation of the post-mortem interval.

Application of Autofluorescence for Confocal Microscopy to Aid in Archaeoparasitological Analyses.

Confocal laser scanning microscopy (CLSM) was used to examine archaeoparasitological specimens from coprolites associated with La Cueva de los Muertos Chiquitos (CMC) located near present-day Durango, Mexico. The eggs for 4 different types of parasites recovered from CMC coprolites were imaged using CLSM to assist with identification efforts. While some of the parasite eggs recovered from CMC coprolites were readily identified using standard light microscopy (LM), CLSM provided useful data for more challenging identifications by highlighting subtle morphological features and enhancing visualization of parasite egg anatomy. While other advanced microscopy techniques, such as scanning electron microscopy (SEM), may also detect cryptic identifying characters, CLSM is less destructive to the specimens. Utilizing CLSM allows for subsequent examinations, such as molecular analyses, that cannot be performed following SEM sample preparation and imaging. Furthermore, CLSM detects intrinsic autofluorescence molecules, making improved identification independent of resource and time-intensive protocols. These aspects of CLSM make it an excellent method for assisting in taxonomic identification and for acquiring more detailed images of archaeoparasitological specimens.

Confusing a Pollen Grain with a Parasite Egg: an Appraisal of "Paleoparasitological Evidence of Pinworm (Enterobius Vermicularis) Infection in a Female Adolescent Residing in Ancient Tehran".

There is often the risk of confusing pollen grains with helminth eggs from archaeological sites. Thousands to millions of pollen grains can be recovered from archaeological burial sediments that represent past ritual, medication and environment. Some pollen grain types can be similar to parasite eggs. Such a confusion is represented by the diagnosis of enterobiasis in ancient Iran. The authors of this study confused a joint-pine (Ephedra spp.) pollen grain with a pinworm egg. This paper describes the specific Ephedra pollen morphology that can be confused with pinworm eggs.

Criteria for identification of Schistosoma mansoni eggs in faecal sediments prepared with the Helmintex method and stained by ninhydrin

Helmintex is a sensitive method used for detecting Schistosoma mansoni eggs. Here, we describe the observed frequency of six proposed criteria associated with the identification of S. mansoni eggs prepared with the Helmintex method and stained with ninhydrin. The efficacy of these criteria in classifying S. mansoni eggs when applied in various combinations was also examined. Nine observers registered the presence or absence of 6 different criteria in 100 eggs using a microscope at 100x magnification. Ninhydrin purple, which was frequently observed, was the criterion associated with the lowest inter-observer variability. At least three criteria were associated with a significantly better performance in egg identification. In conclusion, ninhydrin staining and a combination of criteria are recommended for microscope examination of faecal sediments.

Methods for quantifying eggs and oviposition rate of Dawestrema cycloancistrium (Monogenea: Dactylogyridae), monogenean parasite of Arapaima gigas (Teleostei: Osteoglossidae).

Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas, providing basic biological data for D. cycloancistrium.

Dispersion and infectivity of Toxocara canis eggs after passage through chicken intestine.

Toxocariasis is an important, but neglected, worldwide zoonosis. It is considered a primarily soil-transmitted disease, but food-borne transmission has been associated with the consumption either of raw or undercooked meat of paratenic hosts, including birds. Despite the number of experimental studies carried out to evaluate the behavior of Toxocara spp. larvae in birds, their role in the dispersion of eggs into the environment remains unclear. Thus, this study aimed to evaluate the potential of broiler chickens to release Toxocara canis eggs into the environment, and the infectivity of eggs after passage through the intestine. Forty commercial broiler chickens, aged 60 days, were randomly distributed into three groups. Groups 1 (n = 16) and 2 (n = 16) were orally infected with 5000 embryonated and 5000 unembryonated T. canis eggs, respectively. Group 3 (n = 8) served as a control. Following infection, fecal samples from each chicken were examined using a centrifuge-sedimentation technique. At 24-h, 72-h, and 7-day post-infection (PI), four chickens each from the G1 and G2 groups, and two from the G3 group were killed. After euthanasia, the intestinal content and liver were collected for recovery of T. canis larvae. Results revealed that broiler chickens have the potential to disperse both embryonated and unembryonated T. canis eggs, following 2- to 6-h PI. In addition, the eggs shed into the feces of the G2 birds, after incubation in laboratorial conditions, were infective when they were tested in a bioassay using mice. In conclusion, broiler chickens have the potential of dispersing Toxocara spp. eggs into the environment and the eggs passed through the intestine are infective after being incubated in experimental conditions.

Characterization and localization of primordial germ cells in Totoaba macdonaldi.

The totoaba, Totoaba macdonaldi, is an endangered fish of the Gulf of California with high economic and ecological potential. Therefore, our purpose was to characterize the Primordial Germ Cells (PGCs) of this Sciaenid with two objectives: (1) to provide the basis for PGCs cryopreservation to preserve the genetic resources and (2) to take the first step to know the gonadal genesis and sex differentiation of totoaba. Immunofluorescence analysis performed from 2-cell stage to 8-day after hatch (DAH) shows that Vasa protein is specific for PGCs. These cells were first observed in the peripheral and dorsal regions of the blastodisc at approximately the 50%-epiboly stage and migrated to both sides of embryo body during the development. Finally, at 7 DAH the PGCs of the hatching embryo reached the place where the gonad will be developed. Histology analysis of larvae showed a genital ridge with enclosed PGCs on the dorsal side of the peritoneum at 9 DAH, gonadal primordium growth was observed at 11 DAH as a result of the interaction between PGCs and somatic cells derived from the peritoneum. Results of qPCR showed that vasa expression was restricted to the embryonic and early larval development, highest values were observed in 2-cell and mid-blastula stage suggesting the maternal inheritance of vasa mRNA. These findings support the hypothesis of preformation in T. macdonaldi PGCs. The migration pattern of PGCs allow us to recommend the isolation and subsequent cryopreservation of these cells before 7 DAH when the embryonic and larval development is given at 21 °C.

First morphological and molecular analysis of Eucoleus boehmi like eggs in dogs from Argentina.

The canid parasites Eucoleus aerophilus (syn. Capillaria aerophila) and Eucoleus boehmi (syn. Capillaria boehmi) parasitize the lower and the upper respiratory tract, respectively. Reports and descriptions of these nematodes are scarce in Argentina, possibly due to misdiagnosis of morphologically similar trichuroids eggs, and the lack of knowledge about the species of Eucoleus in this geographical area. Scanning electron microscopy is a useful tool for identification of E. boehmi eggs based on the characteristics of the shell structure which differentiate between species. Molecular analysis complements morphological identification. Until now, there are no studies based on the analysis of E. boehmi eggs in Argentina. The aim of the present work was to study by morphological, morphometric, and molecular analysis, eggs attributable to E. boehmi isolated from dogs naturally infected in Mar del Plata city, Argentina. Eggs isolated from two dog fecal samples were analyzed by light and scanning electron microscopy. A fragment of mitochondrial DNA (mtDNA) of the cytochrome c oxidase subunit I gene (cox1) from eggs was sequenced, and phylogenetic analysis was performed in this study. According to morphological results based on the wall surface ultrastructure, the eggs studied were assigned to E. boehmi. Molecular analysis supported the morphological identification. The divergence of 9-12% with the European isolated could suggest a new geographical genetic variation of E. boehmi, but also question the possible existence of cryptic species. This is the first characterization of E. boehmi eggs in dogs from Argentina.

Grooves surrounding the micropyle decrease the inseminating dose in fish.

In fish with external fertilization, sperm must reach the oocyte through the micropyle to enter the cytoplasm. Fertilization success is then influenced by characteristics of oocytes or sperm. In this study, we evaluated oocyte morphology and sperm motility parameters and their effects on the inseminating dose in a teleost fish Astyanax altiparanae. Interestingly, we found one of the lowest yet described inseminating doses in teleosts (2390 spermatozoa oocyte-1 ml-1). Such a fertilization efficacy may be explained by the long duration of sperm motility (>75 s), the small oocyte diameter (695.119 µm), large micropyle diameter (7.57 µm), and the presence of grooves on the oocyte surface that guides spermatozoon to the fertilization area. Additionally, we have described for the first time a structure that combines grooves on the chorion surface and a ridge in the micropylar area.

The modern morphometric approach to identify eggs of Triatominae.

BACKGROUND: Egg morphometrics in the Triatominae has proved to be informative for distinguishing tribes or genera, and has been based generally on traditional morphometrics. However, more resolution is required, allowing species or even population recognition, because the presence of eggs in the domicile could be related to the species ability to colonize human dwellings, suggesting its importance as a vector. RESULTS: We explored the resolution of modern morphometric methods to distinguish not only tribes and genera, but also species or geographic populations in some important Triatominae. Four species were considered, representing two tribes and three genera: Panstrongylus chinai and P. howardi, Triatoma carrioni and Rhodnius ecuadoriensis. Within R. ecuadoriensis, two geographical populations of Ecuador were compared. For these comparisons, we selected the most suitable day of egg development, as well as the possible best position of the egg for data capture. The shape of the eggs in the Triatominae does not offer true anatomical landmarks as the ones used in landmark-based morphometrics, except for the egg cap, especially in eggs with an evident "neck", such as those of the Rhodniini. To capture the operculum shape variation, we used the landmark- and semilandmark-based method. The results obtained from the metric properties of the operculum were compared with the ones provided by the simple contour of the whole egg, as analyzed by the Elliptic Fourier Analysis. Clear differences could be disclosed between the genera, between the species - among which two very close species (P. chinai and P. howardi), as well as between two allopatric, conspecific populations. The whole egg contour (including the operculum) produced reclassification scores much more satisfactory than the ones obtained using the operculum only. CONCLUSIONS: We propose the outline-based approach as the most convenient characterization tool to identify unknown eggs at the species or population levels.

Beef donor cows with high number of retrieved COC produce more in vitro embryos compared with cows with low number of COC after repeated ovum pick-up sessions.

The aim of the present study was to evaluate whether repeated ovum pick-up (OPU) procedures may affect the efficiency of OPU programs for in vitro embryo production (IVEP) in Bos indicus (Nelore) donors. In addition, the repeatability (r) efficiency of IVEP was also assessed. Data available were from 432 OPU-IVEP sessions that were performed at random stages of the estrous cycle in 36 cycling, nonlactating Nelore donors. Semen from three Nelore bulls was used for the IVF. Donors were submitted to 12 consecutive OPU procedures, with an interval of approximately 30 days between sessions. Data were analyzed as repeated measures using the GLIMMIX procedure of SAS 9.3. Cows yielding ≥15 COCs were defined as "high" COCs and cows with less than 15 COCs were defined as "low" COCs donors. The number of COCs retrieved decreased over time in donors classified with high COCs and remained fairly steady in cows with low COCs at the beginning of the program (Psession*COC retrieved groups = 0.02). Moreover, the number of COCs retrieved (P < 0.0001), and number of blastocysts produced per OPU (P = 0.001) was greater for the high COCs donors compared with the low COCs category, and these results were consistent across OPU sessions. Interestingly, there was no effect of COCs category on the rate of blastocyst development (P = 0.83). In addition, number of blastocysts produced were not affected by repeated OPU (P = 0.37) and interactions between time and COC category (P = 0.72). Similarly, blastocyst rate was not affected by repeated OPU (P = 0.21) and interactions between time and COC category (P = 0.58). Despite of COC category of the donor cows, repeatability was high for the number of COCs retrieved (r = 0.81), number of blastocysts produced per OPU (r = 0.79), and blastocyst rate (0.69). In conclusion, overall numbers of COCs decreased over time in donors classified as having high COCs. However, cumulative amounts of produced blastocysts were greater in donors with high COCs. More importantly, high repeatability was observed in terms of IVEP efficiency. Therefore, IVEP programs can be significantly improved with more aggressive selection toward donors with greater numbers of COCs.

Early development and allometric growth patterns of the grumatã (Prochilodus vimboides Kner, 1859).

The objective of this study was to characterize the early development and allometric growth of the grumatã (Prochilodus vimboides). We describe a sample of 266 eggs and larvae obtained through induced spawning. The eggs were spherical (mean 3.7 mm diameter), exhibited a yellow yolk and were non-adhesive and pelagic after fertilization and hydration. The time elapsed between the early cleavage and post-flexion stages was considered short (328 hours, 8054 hour-degrees) in regard to the development times of other Neotropical rheophilic species, but time to hatching was considerably longer than in other Prochilodus species. The most notable anatomical changes were observed between the end of the yolk larval stage and the beginning of the pre-flexion stage, when the larvae displayed directed swimming and the digestive system became functional, enabling the transition from endogenous to exogenous feeding. After hatching, the larvae grew from 6.04 to 15.15 mm in total length average. Two growth phases were observed at this stage: a non-linear asymptotic curve in yolk-sac larvae, and a linear constant-rate growth phase after exogenous feeding started. Allometric growth related to standard length was positive for head length, negative for eye diameter, and switched between phases from negative to positive in body depth and head height. Morphological development and allometric growth in different larval phases impose drastic anatomical and physiological changes that are synchronic with habitat changes and the flood cycles during the reproductive period.