Reproductive biology of the guitarfish <Emphasis Type="Italic">Rhinobatos hynnicephalus</Emphasis> (Batoidea: Rhinobatidae) in Ariake Bay,Japan

Size at sexual maturity, reproductive cycle, and fecundity of the guitarfish, Rhinobatos hynnicephalus, were examined in Ariake Bay, Japan. Females reached sexual maturity at a larger size than males [total length (TL) at 50% sexual maturity: males, 431 mm; females, 476 mm]. Monthly gonadosomatic indices of males decreased abruptly from July to August. Histological examinations confirmed the presence of mature spermatozoa in the testes in July, with semen in seminal vesicles in July and August. Preovulatory ova were observed in females with near-term embryos in August. Parturition occurred in August, immediately followed by mating, ovulation, and fertilization. Gestation period is approximately 1 year. Fertilized uterine eggs without embryonic development were present throughout the annual reproductive cycle. Embryonic development began in June and ended in August, indicating that R. hynnicephalus undergoes embryonic diapause (9 months). Fecundity increased with TL and ranged from 1 to 9 (mean, 4.4) embryos per litter.     

Intrauterine and post-ovipositional embryonic development of Amerotyphlops brongersmianus (Vanzolini, 1976) (Serpentes: Typhlopidae) from northeastern Argentina

The reproductive biology and embryonic development of Typhlopidae have rarely been explored. This family of snakes includes mostly oviparous species with uterine egg retention, but the morphology and development of embryos remain unknown. This work aimed to describe the embryonic development of Amerotyphlops brongersmianus from the northeast of Argentina. For this purpose, embryos from intrauterine eggs of gravid females and eight post-ovipositional eggs incubated in the laboratory were analyzed. Embryonic stages, corresponding to the early, mid and advanced development, and a hatchling were described. The main organs and systems form during the period of intrauterine embryonic retention. Comparing to other snakes, differences in the development of cranial structures such as encephalic vesicles and mandibular and maxillary processes were identified. After oviposition the development and differentiation of the tissues and organs completes, the body scales develop, the characteristic pattern of pigmentation establishes and the embryo grows and consumes the yolk. On average, the incubation period lasts 55 days. Differences in the stage of development at oviposition among females of different populations were observed. Embryonic retention could extend up to advanced stages of development.     

Captive hybridization of two geographically isolated pygmy angelfish species,Centropyge fisheri and Centropyge resplendens

This study documents the rearing of two pygmy angelfish species, Centropyge fisheri and Centropyge resplendens, and the early life history and reproduction of their hybrid offspring. A C. fisheri female, collected from Hawaii, and a C. resplendens male, captive‐bred from parental stock collected from Ascension Island, were maintained at the hatchery facility for 7 months. Continuous spawning was achieved at a photoperiod cycle of 14L:10D and a water temperature of 26·5° C, range ±1° C. Over the 110 day period, the C. fisheri female spawned 102 times, 57% of which resulted in embryos (fertilized eggs). The mean ±s.d. fecundity per spawn was 730 ± 459 eggs (range 52–1967). Fertility (% eggs that developed into embryos) of all eggs that were preserved was 22·4 ± 25·6%. A total of 235 hybrid juveniles were raised through metamorphosis with an average larval survival of 16·4%. Eight F₁ hybrid juveniles isolated for further study began to display signs of reproductive behaviour c. 300 days post‐hatch (dph). Spawn resulting in non‐fertile eggs were first obtained 319 dph, and fertilized eggs developing into embryos were obtained after 411 dph from at least two female individuals. While no attempt was made at rearing the F₂ larvae, embryo and larval development were normal up to 8 dph. Reproduction and development observed for all hybrid generations in this study were normal, similar to other Centropyge species and indicates a very close phylogenetic relationship between what are currently considered distinct species, e.g. C. fisheri and C. resplendens.     

Hormonal asynchrony and embryonic development

Luteinizing hormone (LH), progesterone and estradiol profiles in peripheral blood serum were compared among parous and nonparous females with normal, abnormal or no embryonic development. Hormonal profiles between parous and nonparous females of the same embryonic status did not differ and the data were combined. Estrous cycle length was longer (P<.05) in parous (22.3±.4 days) than nonparous females (21.0±.4 days). Females with normal developing embryos had a higher serum progesterone concentration at Days 3 and 6 and a lower ratio of estradiol to progesterone than did females with abnormal embryonic development. Females with a normal embryo had higher (P<.05) preovulatory LH peaks than females with abnormal development or no recovery of an oocyte or embryo (34.3±4.7, 11.8±6.8 and 13.3±2.5 ng/ml, respectively). The interval from onset of estrus to LH peak was 8.9±2.1, 13.7±3.7 and 13.5±6.2 hr for females with normal, abnormal or no recovery of an embryo. The lower LH peak, the longer interval from onset of estrus to LH peak, and lower progesterone concentration in peripheral blood serum in females with abnormal embryos or no recovery indicated that these females had a hormonal asynchrony. The hormonal asynchrony may produce an undesirable uterine environment for male and female gametes or embryos which resulted in fertilization failure or embryonic death. In the second experiment, more transferable embryos were obtained when superovulated females received prostaglandin F_2α (PGF_2α) intravenously rather than intramuscularly. Administering PGF₂α intravenously rather than intramuscularly may have caused the demise of the corpus luteum sooner and thereby produced a more normal uterine environment which allowed more embryos to develop normally.     

Non-surgical uterine flushing for the recovery of preimplantation embryos in rhesus monkeys: Lack of seasonal infertility

A non-surgical uterine flushing technique was employed to recover rhesus monkey preimplantation embryos during April–-September, a period thought to be associated with reduced fertility. A total of 22 females of proven fertility, maintained indoors under strict light and temperature control, were employed for the study in which 72 menstrual cycles were monitored. The average length of their menstrual cycle was 27.9 ± 3.8 days. The percentages of cycles that showed normal cyclic patterns of estrogen, LH, and sex-skin color were 84.7%, 91.7%, and 90.3%, respectively. Following natural mating, uterine flushing was performed on days 4–7 of pregnancy. Of 58 attempts, 27 (46.6%) resulted in the recovery of embryonic materials. Two recoveries produced unfertilized oocytes; 20 yielded embryos which were morphologically normal, and 7 yielded damaged and/or degenerate embryos. Luteal function in cycles involving uterine flushings was evaluated by examining ovaries by laparoscopy, ovulation being confirmed in 34 of 35 examinations. Serum progesterone was > 2 ng/ml in 39 of 45 cycles. The conception rate of 46.6% noted in this study was similar (P > 0.4) to those observed from other natural matings in our colony, either during the same period (49.3%; n = 67) or during October–-March (46.9%; n = 113). These results show that rhesus monkeys, maintained under appropriate environmental conditions, can experience normal fertile menstrual cycles throughout the summer months, and extend previous observations to demonstrate, for the first time, that preimplantation embryos can be recovered from this species year-round. © 1993 Wiley-Liss, Inc.     

Effects of temperature experienced during embryonic development on biomass and C and N composition at hatching in Palaemon serratus (Pennant, 1777)

In decapod crustaceans, the conditions experienced during embryonic development trigger phenotypic plasticity of the larvae at hatching. The objective of this study was to test the effects of temperature during embryonic development of Palaemon serratus on the phenotypic plasticity of hatching larvae. We incubated egg-bearing females from eggs laying to hatching at four temperatures (10, 15, 18 and 20°C). Weight, carbon and nitrogen contents were measured on newly laid eggs and on freshly hatched larvae. The duration of embryonic development was negatively correlated with incubation temperature. At 20°C, all females abandoned their eggs during development. Incubation temperature had no effect on the weight and the percentage of N of the larvae at hatching, while it did affect their percentage of C and their C/N ratio. Embryos incubated at 10°C seemed to produce larvae with fewer lipid reserves than those incubated at 15 and 18°C. They probably overconsumed their lipid reserves to compensate for the metabolic losses due to the low temperature. These results provide information on the link between maternal investment per egg and larval development in P. serratus.     

Do pregnant lizards resorb or abort inviable eggs and embryos? Morphological evidence from an Australian skink,Pseudemoia pagenstecheri

Although pregnant viviparous squamates are sometimes claimed to be able to resorb inviable eggs and embryos from the uterus, definitive evidence for such resorption is not available. After placing pregnant female Pseudemoia pagenstecheri into conditions under which embryonic development is terminated, we periodically harvested the gravid oviducts and examined them histologically. Females contained abnormal and degenerating eggs and embryos that had died in various stages of development. Dead embryos had undergone extensive cytolysis, dissolution, and aseptic necrosis and vitelline masses showed signs of deterioration and passage down the oviduct. The uterine mucosa lay in direct contact with the vitelline material, with no intact shell membrane intervening between them. Yolk was sometimes displaced into the exocoelom and allantoic cavity due to rupture of the extraembryonic membranes. Histological examination revealed no evidence of the uptake of yolk by the uterine epithelium or its accumulation in the subepithelial connective tissue. In many specimens, the uterine epithelium showed minuscule, apical granules. The position, appearance, and staining properties of the granules suggests them to be secretory, a manifestation of placentotrophy. Our observations indicate that P. pagenstecheri females retain dead eggs and embryos for several weeks or longer, yet do not resorb them during that period. This lizard is the second placentotrophic skink species in which resorption has been suspected, but in which abortive eggs appear to be retained or extruded instead of being resorbed by the oviducts. Researchers should not assume that squamates can digest and resorb oviductal eggs without definitive morphological evidence.     

Plasticity and limitations of extended egg retention in oviparous Zootoca vivipara (Reptilia: Lacertidae)

The transition between oviparity and viviparity in reptiles is generally accepted to be a gradual process, the result of selection for increasingly prolonged egg retention within the oviduct. We examined egg retention plasticity in an oviparous strain of the lacertid lizard Zootoca vivipara, a species having both oviparous and viviparous populations. We forced a group of female Z. vivipara to retain their clutch in utero by keeping them in dry substrata, and assessed the effect on embryonic development and hatching success, along with offspring phenotype and locomotor performance. Forced egg retention for one additional week affected the developmental stage of embryos at oviposition, as well as hatchling robustness and locomotor performance. However, embryos from forced clutch retention treatment reached one stage unit more than control embryos at oviposition time. Embryos from control eggs were more developed than embryos from experimental eggs after approximately the same period of external incubation, showing that embryonic development is retarded during the period of extended egg retention, despite the high temperature inside the mother's body. Significant differences in external incubation time were only found in one of the two years of study. Hatching success was much lower in the experimental group with forced egg retention (21.1%) than in the control group (95.4%). Therefore, we conclude that there are limitations that hinder the advance of intrauterine embryonic development beyond the normal time of oviposition, and that extended egg retention does not represent clear advantages in this population of Z. vivipara. Nevertheless, the fact that some eggs are successful after forced egg retention could be advantageous for the females that are able to retain their clutch under unfavourable climatic conditions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 75–82.     

A 4-year summary of the nonsurgical recovery of baboon embryos: A report on 498 eggs

A nonsurgical embryo recovery procedure, developed to allow the economical acquisition of cleavage stage baboon embryos, has been successfully used for 4 years. With this technique, 498 eggs have been recovered from 979 uterine flushes (50.9%) on 71 baboons. Of 467 eggs recovered from mated baboons, 290 (62.1%) were fertilized. Papio anubis females provided a higher percentage of fertilized eggs (75.3%) than did Papio hamadryas (47.8%) or Papio cynocephalus (44.3%) females following exposure to males during estrus, although sexual preference may be responsible for the reduced fertilization rate in the P. cynocephalus females. Recovery rates from individual baboons ranged from 0% (n = 11) to between 66% and 93% for ten baboons from each of which 12–33 eggs have been recovered. Fertilized eggs were at the two-cell (n = 23) to blastocyst (n = 53) stage at recovery 1–6 days postdeturgescence (PD) of the sex skin, with morulae (n = 84) being the most frequent cell stage recovered (30%). The optimum time for performing the procedure was the third day PD, when 113 (40%) embryos were recovered. The abilities of baboons to become pregnant and to provide fertilized embryos were significantly related (P < 0.005), allowing the embryo recovery technique to be used as a screening procedure for evaluating baboon fertility.     

The effect of tannin concentration and egg unsticking time on the hatching success of tench Tinca tinca (L.) larvae

The influence of dose and time of eggs exposure in tannin solution on tench embryonic development, survival of embryos and percentage of larvae hatched were studied. The eggs obtained under controlled conditions from 11 tench females were fertilized with semen from 7 males and then rinsed for 1 h in Woynarovich solution (40 g urea, 30 g NaCl per 10 dm³ of water). Random samples (50 cm³) of the fertilised eggs were placed into three tannin solutions 0.05, 0.1 or 0.15% for 30, 60 or 90 s, then they were transferred to Weiss jars where incubation at 25°C took place. Tannin solution of 0.05% for 30–90 s or 0.1% for 30 s allowed effective unsticking of eggs and resulted in a very high per cent of hatched larvae. Extending the eggs rinsing time to 60 s in 0.10 and 0.15% solutions resulted in a high mortality of embryos during hatching because of hardened egg capsule.     

Effect of temperature on the morphometric development of eggs in the prawn Macrobrachium americanum (Caridea: Palaemonidae) and larval success under experimental conditions

Abstract

This study evaluated the effect of temperature on morphometric features of the egg during the embryonic development of the prawn Macrobrachium americanum and the relationship with hatching and the survival of the larvae. Berried females were grouped (n = 3) and reared at three different temperatures, 26, 29, and 33 °C, for which seven developmental stages were recognized. At each stage, the apical and sagittal diameters of the eggs were measured, the volume was calculated, and the weights were recorded. Additionally, the duration of embryonic development, hatching percentage, and larval survival were determined. At 29 and 33 °C, the eggs’ volume increased by 50%, but at 26 °C, the increase was 25%. Larvae from eggs incubated at 33 °C died one day after hatching. At 29 °C, larvae survived until Zoea VII. Larvae from eggs incubated at 26 °C died at the end of Zoea I. The number of days of embryonic development was 20.5 ± 1.5 (26 °C), 15 ± 1 (29 °C), and 12 ± 1 (33 °C). A temperature of 29 °C was the most favorable for embryonic development in M. americanum.     

Ultrasonographic and hormonal monitoring of pregnancy in the saddle back tamarin,Saguinus fuscicollis

Ultrasonography was used in six saddle back tamarin females (Saguinus fuscicollis) to diagnose pregnancy, monitor the patterns of uterine growth and embryonic/foetal development and examine the incidence loss of single embryos/foetuses. Pregnancy was reliably diagnosed 17 days after conception, 10 days earlier than by plasma progesterone measurement. The patterns of uterine and embryonic/foetal growth paralleled those reported for the common marmoset, including a delay in embryonic development. The results support the hypothesis of retardation of organogenesis in most callitrichid species. Individual embryos could be reliably identified from day 50 of pregnancy; a loss of single embryos/foetuses after this stage did not occur. All pregnancies were carried to term, resulting in five times twins and one singleton. The smaller litter size compared to the common marmoset may be due to loss of single embryos at earlier stages of pregnancy or to a lower ovulation rate.     

Fecundity and reproductive output of the caridean shrimp Periclimenes paivai associated with scyphozoan jellyfish

Periclimenes paivai is notable for its symbiotic lifestyle with jellyfish. The objective of this study was to investigate the fecundity and reproductive output of females, and specifically to determine whether females protected in their host have a greater reproductive success than other shrimp species. All anatomical parts of the medusae were analyzed and the P. paivai individuals were separated. Among 83 females analyzed, 65 presented embryos in the first developmental stage, and 18 were in the final stage of development. The mean fecundity was 229.08 ± 120.04 in initial-stage embryos and 191 ± 114.76 in final-stage embryos. We observed a positive relationship between the embryo number and the female size; however, the embryo number was not related to the embryonic stage, which indicates that females did not lose their embryos during the incubation period. The weight of brood mass during production is closely related to the female weight according to the results of linear regression, as fecundity increased with female size. In its symbiosis, P. paivai can increase the amount of energy used to produce embryos (mean reproductive output = 10.38%) and can elevate the reproductive success.     

Reproductive biology of female striped marlin Kajikia audax in the western Pacific Ocean

Length and mass data for 1260 (536 females, 683 males, 41 sex unknown) striped marlin Kajikia audax were collected at the fish markets of Tungkang, Singkang and Nanfangao from July 2004 to September 2010. Of these samples, 534 gonads (236 females and 298 males) ranging from 95 to 206 cm in eye‐to‐fork length (L _EF ) and 8 to 88 kg in round mass (M _R), were collected. Chi‐square tests indicated sex ratios were homogeneous among months in 2004 and 2006–2008, but not in 2005, 2009 and 2010; and there were significant differences in sex ratio by size. The overall sex ratio (R _S ) differed significantly from the expected 0·5. Kajikia audax are sexually dimorphic and the proportions of females increased with size between 140 and 210 cm L _EF . Reproductive activity was assessed using a gonado‐somatic index (I _G ), external appearance of the gonads and histological examination and results indicated that the spawning season occurred from April to August with a peak in June to July. Based on histological observations and the distribution of oocyte diameters, K. audax are multiple spawners and their oocytes develop asynchronously. The estimated length‐at‐50% maturity (L _EF50 ) was c . 181 cm (c . 4·8 years of age) for females. The proportion of reproductively active females in the spawning season with ovaries containing postovulatory follicles (0·27) indicated that they spawned every 3·7 days on average. The hydrated oocyte method estimated mean ± S.D. batch fecundity (F _B ) to be 4·4 ± 2·02 million eggs; average relative fecundity was 53·6 ± 13·9 oocytes g^?1 M _R; and the average annual fecundity was 181·3 ± 48·3 million eggs. The parameters estimated in this study are key information for stock assessments of K. audax in the north‐western and central Pacific and will contribute to the conservation, management and sustainable yield of this species.     

Delayed development in Fischer's pygmy fruit bat, Haplonycteris fischeri, in the Philippines

A long delay in post-implantation embryonic development was detected in Fischer's pygmy fruit bats (palaeotropical fruit bats of the suborder Megachiroptera), the first time such a delay has been demonstrated outside the bat suborder Microchiroptera. Samples of bats were obtained from the Philippines over 5 years, and reproductive tracts were preserved and examined using standard histological techniques. Most parous female pygmy bats were impregnated in June, within a few weeks of parturition, and the embryos underwent superficial implantation at the anterior end of the uterus contralateral to the previously gravid uterus. Shortly thereafter, the rate of embryonic growth slowed tremendously for up to 8 months. During the period of delay, the mean length of the embryoblast increased only from 280 microns to 520 microns. In March of the following year, the developmental rate increased, and the embryos completed development in the next 3 months. The 8-month delay gives these bats a gestation period of 11.5 months, the longest known in bats. Most nulliparous females become pregnant at an age of 3-5 months, and their embryos entered a similar delay that terminated in March or April, after 2-6 months of delay. Males showed signs of fertility throughout the entire year, but testis volume was highest during May, June and July, at about the time when most females become receptive.     

Some effects of suction on the hatching eggs of Meloidogyne javanica

Development and hatch of eggs of Meloidogyne javanica was independent of suction between pF o and 3·6 but decreased rapidly between pF 3·6 and 4·2. Water was lost from the extracellular fluid of eggs containing developing embryos when the suction was above pF 3·6, causing a decrease in the mean volume of the eggs. The vitelline membrane of an egg is probably semipermeable and the osmotic pressure of the contents about 4 atmospheres (pF 3·6). The volume of the cellular contents of an egg did not increase during development and so the hydraulic conductivity of the soil is probably unimportant in hatching. The results suggest that eggs of M. javanica hatch over a wide range of soil moistures. The inhibition of hatch at high suctions, involving the reversible removal of water, is a likely survival mechanism.     

Reproduction of Lumbricillus rivalis (Levinsen) in laboratory cultures and in decaying seaweed

The cocoon production of 144 Lumbricillus rivalis cultured in pairs at 10 ± 1 °C was high over the first 2 weeks of breeding activity and then declined, chiefly because of high mortality. Cocoon deposition lasted for between 1 and 16 weeks, eight pairs of worms producing cocoons for 9 weeks and one pair for 16 weeks. During the total period of cocoon deposition over 9000 eggs (mean 17·4 per cocoon) were deposited. Two decaying wrack bed populations of L. rivalis showed a low level of cocoon and egg production in autumn, rising to an annual maximum in late winter/early spring. In these populations the mean egg content varied seasonally from 17·1 to 47·8 eggs per cocoon. When cocoons in the laboratory were transferred from the site of deposition to incubation dishes 31% hatched, but those left in the substrate showed a 92% hatch. In the naturally occurring populations 19% of the cocoons detached from seaweed fronds hatched, but 62% of those left in situ. Eggs and worm embryos developed to relatively late stages in most cocoons, whatever the rate of hatching; development often continued for up to 2 months after deposition without hatching. Over 50% of the fertile eggs in cocoons from decaying wrack hatched and developed to 5 mm worms.     

Reproductive biology of the fanray, <Emphasis Type="Italic">Platyrhina sinensis</Emphasis> (Batoidea: Platyrhinidae) in Ariake Bay,Japan

The reproductive biology of the fanray, Platyrhina sinensis, was examined in Ariake Bay, Japan, from May 2002 until December 2006. Females reached sexual maturity at a larger size than males [total length (TL) at 50% sexual maturity: male, 393 mm; female, 421 mm]. The present data support a distinct annual reproductive cycle for P. sinensis. The gonadosomatic index (GSI) for mature males showed a clear seasonal trend, declining from August to November. Histological observations showed that mature sperm in the testes occurred from August to November when monthly GSI declined. Concomitantly, pre-ovulatory ova were observed in females collected from August to November. These data indicate that mating, ovulation and fertilization occurred from August to November. Near-term embryos, neonates and recent post-partum females also occurred from August to November. Additionally, all post-partum females possessed large pre-ovulatory ova. Parturition occurred from August to November followed immediately by mating, ovulation and fertilization. Mature females become pregnant every year, and the gestation period is almost 1 year. Fertilized uterine eggs without macroscopic embryonic development were present throughout the annual reproductive cycle, indicating that P. sinensis utilizes embryonic diapause as its reproductive strategy. Both reproductive tracts of females were functional, and fecundity ranged from 1 to 12 with a mean of 6.0, increasing with TL.     

Reproductive biology of guitar,Rhinobatos hynnicephalus

Synopsis Reproductive biology of the guitarfish,Rhinobatos hynnicephalus, from Xiamen coastal waters is described. Males have two functional testes. Spermatogenic cells in different seminiferous follicles are at different developmental stages while those in the same follicle are at the same stage. The development of claspers suggests that males mature at 380–400 mm TL. Females mature at 390–440mm TL. Both ovaries are functional. The first generation of ovarian eggs reach mature size when 22–24mm in diameter in April or May. The subsequent crop of eggs is ready for ovulation when the intrauterine embryos reach full term. The guitarfish is aplacentally viviparous. Longitudinal folds were observed on the internal wall of the uterus. Gestation takes one year and parturition takes place in June or July. Fecundity ranges from 2 to 9, with the large females usually being more fecund. Of 29 embryos ranging from 52–157mm TL, there were 15 females and 14 males indicating an embryonic sex ratio 1:1.     

Embryonic development of the Caridean prawn Macrobrachium mammillodactylus (Crustacea: Decapoda: Palaemonidae)

The freshwater knob-tooth prawn Macrobrachium mammillodactylus is a commercially exploited species in the Philippines. To study the biology of this species, broodstock from the wild was collected, transported to the laboratory and kept in pairs in indoor polyethylene tanks for breeding. Eggs from berried females were sampled to follow the stages of embryonic development until hatching to zoea larva. It took 18.0?±?2.1?days for the eggs to hatch at ambient water temperature between 25 and 28?°C. The morphological landmarks of development at the different stages (pre-cleavage, cleavage, blastula, pre-nauplius, post-nauplius and pre-hatching) of the live embryos are described. Incremental percentage staging was adopted from 0% at fertilization to 100% at hatching and were matched with corresponding morphological development. Egg volume increased significantly toward the mid-to-later stages of development. The eye index also showed a significant increase as the egg developed. The colour of the egg mass changed from light olive green to grey as the eggs progressed in development. The general pattern of development was comparable to other members of the genus Macrobrachium.