Lower fecundity in parthenogenetic geckos than sexual relatives in the Australian arid zone

Theoretical models of the advantage of sexual reproduction typically assume that reproductive output is equal in sexual and parthenogenetic females. We tested this assumption by comparing fecundity between parthenogenetic and sexual races of gekkonid lizards in the Heteronotia binoei complex, collected across a 1200 km latitudinal gradient through the Australian arid zone. Under laboratory conditions, parthenogenetic geckos had approximately 30% lower fecundity when compared with their sexual progenitors, irrespective of body size. Reflecting clutch-size constraints in gekkonids, this fecundity difference was mainly because of fewer clutches over a shorter period. When parthenogens were compared more broadly with all coexisting sexual races across the latitudinal gradient, parthenogens had lower fecundity than sexuals only when corrected for body size. Differences in fecundity between parthenogens and coexisting sexual races depended on which sexual race was considered. There was no significant relationship between fecundity and parasite (mite) load, despite significantly higher mite loads in parthenogens than in sexual races.     

Increased capacity for sustained locomotion at low temperature in parthenogenetic geckos of hybrid origin

The evolution of parthenogenesis is typically associated with hybridization and polyploidy. These correlates of parthenogenesis may have important physiological consequences that need be taken into account in understanding the relative merits of sexual and parthenogenetic reproduction. We compared the thermal sensitivity of aerobically sustained locomotion in hybrid/triploid parthenogenetic races of the gecko Heteronotia binoei and their diploid sexual progenitors. Endurance times at low temperature (10 degrees , 12.5 degrees , and 15 degrees C, 0.05 km h(-1)) were significantly greater in parthenogenetic females than in sexual females. Comparison of oxygen consumption rates during sustained locomotion at increasing speeds (0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 km h(-1), 25 degrees C) indicated that parthenogenetic lizards have higher maximum oxygen consumption rates and maximum aerobic speeds than do female sexual geckos. In addition, parthenogenetic geckos showed greater levels of voluntary activity at 15 degrees C than did sexual geckos, although this pattern appears strongest in comparison to male sexual forms. Parthenogenetic lineages of Heteronotia thus have an advantage over sexual lineages in being capable of greater aerobic activity. This result is opposite of that found in prior studies of parthenogenetic teiid lizards (genus Cnemidophorus) and highlights the idiosyncratic nature of phenotypic evolution in parthenogens of hybrid origin.     

Ovarian maturation of Penaeus subtilis (Decapoda: Penaeidae): A new insight to describe oocyte development and somatic structures

We observed the presence of follicular cells (FC) in the ovaries of Penaeus subtilis (n = 1198), which led us to classify the development of germ cells into six phases: oogonia, previtellogenic oocytes, primary and secondary vitellogenic oocytes, mature oocytes and atretic oocytes. The FC changes their shape according to the development of germ cells and showed a different distribution along the ovary, which allowed differentiating vitellogenic oocytes into primary and secondary. We also observed that the postovulatory follicles (POF) are composed of follicular cells. The presence of POF in penaeids ovaries is rarely reported, but allows the differentiation between spent and resting stages, commonly grouped in reproductive biology research. Furthermore, observation of ovarian lining was useful to differentiate immature females from females that had spawned at least once. Thus, ovarian development was classified into six stages: immature, early developing, advanced developing, ripe, spent and resting. The distribution and shape variations of FC, ovarian lining features and presence of POF were considered crucial for the classification of ovarian maturation stages. The methods developed here may improve estimates of their reproductive cycle, size at first maturity and spawning season, which are important variables in future studies of the reproductive dynamics.     

Ovarian histology of the placentotrophic Mabuya mabouya (Squamata, Scincidae)

Ovarian structure and folliculogenesis of females at different reproductive stages are described for the viviparous placentotrophic lizard Mabuya mabouya. The small ovaries have a thin wall formed by the ovarian epithelium and a thin tunica albuginea. One to two germinal beds that contain numerous oogonia and developing primordial follicles are derived from the ovarian epithelium and are next to the ovarian hilum. The ovarian cortex contains follicles at different stages of development, corpora lutea, and atretic follicles. The yolk nucleus and Balbiani complex were not evident in the ooplasm of previtellogenic follicles. The follicular epithelium of these follicles is polymorphic, as in other species of Squamata, but the larger cells are spherical and monolayered rather than pyriform. The zona radiata of the preovulatory follicles is less developed than in lecithotrophic species. These features suggest a decrease in metabolic and absorptive processes during follicular growth. In preovulatory follicles (1.5-1.8 mm diameter), primordial yolk vacuoles and small cortical granules are deposited in the ooplasm instead of fatty yolk platelets, so that only one stage of vitellogenesis is observed. Polyovular atretic follicles occur in some females. Follicular atresia is minimal for preovulatory follicles, but is more frequent in follicles with polymorphic epithelia. In the corpus luteum, the luteal tissue is formed from granulosa cells and luteolysis occurs during the late gastrula -- late neurula embryonic stages. Thus, the maintenance of gestation from the pharyngula to preparturition stages seems to be related to secretion of extraluteal progesterone, possibly of placental origin. These observed ovarian features are related to the high degree of placental complexity of this species and show that the evolution of advanced placentotrophy in species of this lineage has been accompanied by concomitant changes in ovarian function.     

Reproductive suppression in eusocial Cryptomys darnavensis colonies: socially-induced infertility in females

Inhibition of reproduction occurs in colonies of the Damaraland mole-rat ( Cryptomys damarensis ), where one female and usually one male are reproductively active. They remain the sole reproductive animals thoughout their stay in the colony, which in the field may exceed five years.
An 18-month study on a captive colony of C. damarensis shows that non-reproductive females remain anovulatory and always have concentrations of urinary progesterone lower than that of the reproductive female 10.7 8.8 nmols/mmol creatinine (n = 85), although their progesterone concentrations are slightly elevated when the reproductive female is early in pregnancy. In contrast the reproductively active female has elevated concentrations of progesterone 63.3 70.1 nmols/mmol creatinine (n= 14).
Standard histological together with immunohistochemical examination of the ovarian structure shows that follicular development in the non-reproductive females is halted at varying stages prior to ovulation and that the unruptured follicles luteinize. These unruptured luteinized follicles stain positive for 3β hydroxysteroid dehydrogenase—the enzyme catalysing the synthesis of progesterone from pregnenolone. It is possible that the low levels of circulating progesterone produced by the luteinized follicles in the non-reproductive females in the colony are sufficient to feedback on the hypothalamo-pituitary axis and prevent the surge of LH necessary for ovulation.
Behavioural studies provide corroborative evidence for sexual suppression. Thus the non-reproductive females in the colony are never involved in courtship or copulatory behaviour. nor do they actively solicit males in the colony. The reproductive female, however, plays an active role in mate selection and is the initiator in courtship behaviour.
The suppression of ovulation in non-reproductivc females is maintained for as long as there is a reproductive female in the colony.     

Noninvasive monitoring of follicle development,ovulation, and corpus luteum formation in the marmoset monkey (Callithrix jacchus) by ultrasonography

This is the first paper to describe ovarian changes associated with follicular growth, ovulation, and corpus luteum (CL) formation as monitored by ultrasonography in a multiovular primate, the marmoset monkey (Callithrix jacchus). Examinations were carried out transabdominally on unsedated females using a 10 MHz probe. Cycles were monitored by plasma progesterone and controlled by administration of prostaglandin F2α (PGF). The reliability of ultrasound was validated by comparing findings with direct observation of the ovaries at laparotomy. In eight females, 25 follicles were counted, of which 92% were depicted correctly by ultrasound. Of 14 CLs in five females, number and position were confirmed at laparotomy for 78%. Ultrasound examinations of ovaries throughout the follicular and luteal phase were performed in eight cycles and related to plasma profiles of luteinizing hormone (LH) and progesterone. One of these cycles was anovulatory. In the remaining seven cycles, 19 follicles were considered ovulatory follicles since they were seen on consecutive days and found again as CLs. Growth of individual follicles was monitored by measurements of follicle diameter from day 7 onward. Disappearance of follicles or changes in echogenicity were noted between days 9 and 11, preventing further measurements. Mean follicle size increased from 2.1 mm (range 1.6 mm–2.7 mm) on day 7 to 3.2 mm (range 2.7 mm–4.0 mm) on the day last seen. With one exception, the day follicles were last seen by ultrasound was consistent with the day of the preovulatory LH surge (day 9–11). The postovulatory rise in progesterone occurred 1–2 days later (day 11–13). These findings suggest that the day of ovulation as observed by ultrasound was characterized by either disappearance of follicles or increased follicular echogenicity. In conclusion, ultrasonography provides a reliable, noninvasive method for examinations of the ovarian cycle in the marmoset monkey. © 1996 Wiley-Liss, Inc.     

Morphological patterns of cell death in ovarian follicles of primary and secondary growth and postovulatory follicle complex of the annual killifish Millerichthys robustus (Cyprinodontiformes: Cynolebiidae)

The dynamics of cellular development and homeostasis of the ovary depend on the balance between proliferation and cell death throughout the reproductive cycle. Millerichthys robustus is an annual fish whose ovarian follicles develop asynchronously, allowing daily reproduction from sexual maturity until death. The objective of this research is to describe, histologically, the processes of follicular atresia and regression of postovulatory follicular complexes (POC) throughout a reproductive cycle of M. robustus. Patterns of cell death were documented by apoptosis in atretic follicles and POC, and necrosis in the POC after ovulation with an associated inflammatory response. Atretic follicles were seen from the onset of sexual maturity, during week three post-hatching (PH), both in primary growth (from the Cortical alveoli step, with folliculogenesis completed) and secondary growth Stages, with a higher prevalence in the latter. POCs were observed in different stages of regression from week four PH until the death of the fish. The apoptotic characteristics found were: (i) fragmentation of the nuclear membrane and zona pellucida, and liquefaction of the cortical alveoli and yolk; (ii) follicular cells becoming phagocytic, increasing their size, and migrating within the oocyte; and (iii) formation of an intrafollicular lumen, a product of phagocytosis of the oocyte constituents and dispersed pigments that remain after the digestion of yolk and cortical alveoli. The morphological changes of the follicular cells of the POC, from a squamous morphology after ovulation to columnar during its regression with PAS+ contents, was documented, suggesting a secretory activity.     

Evolutionary Dynamics of Mitochondrial DNA Duplications in Parthenogenetic Geckos, Heteronotia Binoei

Mitochondrial DNA (mtDNA) from triploid parthenogenetic geckos of the Heteronotia binoei complex varies in size from 17.2 to 27.6 kilobases (kb). Comparisons of long vs. short genomes using restriction endonucleases revealed a series of tandem direct duplications ranging in size from 1.2 to 10.4 kb. This interpretation was supported by transfer-hybridization experiments which also demonstrated that coding sequences were involved. Some of the duplications have been modified by deletion and restriction site changes, but no other rearrangements were detected. Analysis of the phylogenetic and geographic distribution of length variation suggests that duplications have arisen repeatedly within the parthenogenetic form of H. binoei. The parthenogens, and thus the duplications, are of recent origin; modifications of the duplicated sequences, particularly by deletion, has therefore been rapid. The absence of duplications from the mtDNA of the diploid sexual populations of H. binoei reinforces the correlation between nuclear polyploidy and duplication of mtDNA sequences reported for other lizards. In comparison to the genomes of sexual H. binoei and of most other animals, the mtDNA of these parthenogenetic geckos is extraordinarily variable in length and organization.     

In vitro maturation,fertilization and development of domestic cat oocytes recovered from ovaries collected at three stages of the reproductive cycle

This study was conducted to examine the effect of the donor cat's reproductive cycle stage on in vitro maturation (IVM), in vitro fertilization (IVF), and in vitro development of oocytes recovered from ovaries that were collected and stored at 35 degrees C for a short period (1-6 h). Based on the presence or absence of follicles and corpora lutea, the ovarian pairs collected were classified into inactive, follicular, or luteal stages. Nuclear status of 161 cumulus-oocyte complexes (COCs) were examined immediately after recovery; 91.3% of the oocytes were found to be at the immature germinal vesicle (GV) stage, and 3.7% of the oocytes were at metaphase II (MII) stage. The percentage of the oocytes at the GV stage was significantly lower in the follicular stage than in the inactive stage (P < 0.01). Of the oocytes from the follicular stage, 9.1% were at MII stage. After culture for 24 h, however, the proportions of oocytes that reached metaphase I and MII were not different among the reproductive cycle stages of the ovaries collected (P > 0.05). After co-incubation with sperm, 63.1% of oocytes were fertilized, but there were no significant differences among the reproductive cycle stages of the ovaries with respect to the proportions of normal and polyspermic fertilization. However, the number of oocytes reaching cleavage stage and development to the morula and blastocyst stages from follicular stage ovaries were significantly lower (P < 0.05) than those obtained from inactive and luteal stage ovaries. These results indicate that the reproductive cycle stage of donor cat ovaries, stored at 35 degrees C, has no apparent effects on the frequencies of maturation and fertilization of oocytes, but influences developmental competence of the oocytes following IVM or IVF.     

Pattern of ovarian protein synthesis and secretion during the reproductive cycle of Scotophilus heathi: synthesis of an albumin-like protein

Ovarian proteins synthesized de novo and secreted in vitro were investigated during different stages of the reproductive cycle of Scotophilus heathi. We found increased ovarian protein synthesis and secretion during the recrudescence and the preovulatory periods, coinciding with two peaks of follicular development and steroidogenesis. The ovaries synthesized protein at a low rate during quiescence and the late phase of delayed ovulation. In vitro analysis using ³⁵S-methionine incorporation showed increased synthesis of 66 kDa protein during delayed ovulation, but secretion of this protein declined markedly during the preovulatory period. N-terminal sequencing of the 66 kDa protein showed that it shares 70% homology with human serum albumin. Immunocytochemistry indicated that this protein is found primarily in the granulosa cells of the follicles. Whether the increase in albumin production by the ovaries during delayed ovulation is associated with a hyperinsulinemic and hyperandrogenic condition requires further investigation.     

Pattern of ovarian protein synthesis and secretion during the reproductive cycle of Scotophilus heathi: synthesis of an albumin-like protein.

Ovarian proteins synthesized de novo and secreted in vitro were investigated during different stages of the reproductive cycle of Scotophilus heathi. We found increased ovarian protein synthesis and secretion during the recrudescence and the preovulatory periods, coinciding with two peaks of follicular development and steroidogenesis. The ovaries synthesized protein at a low rate during quiescence and the late phase of delayed ovulation. In vitro analysis using 35 S-methionine incorporation showed increased synthesis of 66 kDa protein during delayed ovulation, but secretion of this protein declined markedly during the preovulatory period. N-terminal sequencing of the 66 kDa protein showed that it shares 70% homology with human serum albumin. Immunocytochemistry indicated that this protein is found primarily in the granulosa cells of the follicles. Whether the increase in albumin production by the ovaries during delayed ovulation is associated with a hyperinsulinemic and hyperandrogenic condition requires further investigation.     

成体雌性小熊猫卵巢组织学观察

2000 年至2009 年,12 只固定于10% 福尔马林中非生殖系统疾病死亡的小熊猫卵巢组织,按常规组织学技术制作组织切片,HE 染色,光学显微镜观察。结果:(1)不同发情时期卵巢均有原始卵泡、初级卵泡和次级卵泡分布。发情期的卵巢未观察到典型的成熟卵泡和卵母细胞; (2)原始卵泡数量较少,初级卵泡数量较多,多数初级卵泡和大多数的次级卵泡都处在闭锁状态;(3)卵泡腔出现之前,卵母细胞的直径和卵泡直径同时增长;卵泡腔出现之后,卵母细胞直径增长较慢,卵泡直径增长较快; (4)不同发情时期的小熊猫卵巢均存在大量的间质腺细胞;(5)妊娠小熊猫和发情间期无妊娠小熊猫的卵巢均有发育正常的黄体;(6)卵泡细胞发育呈低柱状至柱状时出现透明带。结论:(1) 卵泡闭锁主要发生在初级卵泡阶段,仅少数卵泡能发育至次级卵泡;(2)卵母细胞和卵泡生长呈双相生长的趋势; (3) 不同发情时期的小熊猫卵巢间质腺都发达; (4)发情排卵后,非妊娠黄体与妊娠黄体维持的时间相似,证实了小熊猫存在假孕现象。     

Variation of reproductive effort between parthenogenetic and sexual populations of the scorpion Tityus columbianus

Abstract. Geographic differences in reproductive effort were examined between sexual and parthenogenetic populations of the Colombian scorpion Tityus columbianus , from Iza (sexual) and from Mosquera (unisexual). The sexual females from Iza were significantly larger and had significantly greater relative litter mass (RLM) than the parthenogenetic ones from Mosquera. In both populations litter size increased significantly with female body size.
Litter size and RLM in the sexuals averaged 12.7 and 0.49 respectively, and in the unisexuals 8 and 0.36. We suggest that the higher values are related to greater primary productivity at the Iza site.     

Morphological and quantitative evaluation of the ovarian recrudescence in Nile tilapia (Oreochromis niloticus) after spawning in captivity

The Nile tilapia is one of the most important fish species for aquaculture worldwide. Understanding their reproductive biology is essential for improving their aquaculture methods. The morphological and quantitative dynamics of ovarian recrudescence of Oreochromis niloticus was studied for 21 days postspawning. To accomplish this, breeding females were kept in controlled conditions and ovarian samples were collected weekly for histological, ultrastructural and morphometric analyses. Ovarian follicle morphology revealed an intense synthesis activity of the follicular cells, which actively contributed to formation of the zona radiata and oocyte development following spawning. Recently spawned ovaries contained follicles at all developmental stages, but they were predominantly early primary growth (～42%) and full‐grown follicles (～20%). Remnants of spawning, postovulatory follicle complexes represented approximately 5% of the former ovarian follicles immediately after spawning, and less than 1% after 7 days. Atretic follicles accounted for approximately 2% of the follicles studied during the period. The stock of primary growth follicles was stable during ovarian recrudescence, indicating their availability for continuous recruitment. Only the frequency of full‐grown follicles significantly increased in the ovaries during recrudescence, representing approximately 35% of the follicles 21 days postspawning. The diameters of all follicles were significantly different between the periods analyzed. The ovaries' morphological characteristics, the maintenance of young follicles stocks and the gradual and significant increase in the proportion and diameter of full‐grown follicles showed a rapid ovarian recovery and follicular growth of O. niloticus, in 21 days at 29.5°C, necessary for the next spawning. J. Morphol. 275:348–356, 2014. © 2013 Wiley Periodicals, Inc.     

Eight highly polymorphic microsatellite loci for the Australian gecko Heteronotia binoei

Eight highly polymorphic dinucleotide microsatellite loci were developed for the Bynoe's gecko, Heteronotia binoei. Across the species as a whole, expected heterozygosities for the loci range from 0.59 to 0.92, with observed numbers of alleles ranging from 13 to 27. All eight loci successfully amplify in each of the three most widespread sexual chromosome races of Heteronotia binoei, and with the exception of one locus in one race all are polymorphic. All eight loci also amplify in hybrid parthenogenetic Bynoe's geckos, in several other sexual chromosome races, and in related Heteronotia species.     

Changes in follicle-stimulating hormone and follicle populations during the ovarian cycle of the common marmoset

The common marmoset (Callithrix jacchus) belongs to the family Callitrichidae, the only anthropoid primates with a high and variable number of ovulations (one to four). An understanding of folliculogenesis in this species may provide some insight into factors regulating multiple follicular growth in primates. The aims of this study were to characterize in detail changes in the antral follicle population at different stages of the ovarian cycle, to characterize the marmoset FSH profile, and to relate cyclic changes in FSH to changes in follicle sizes and circulating estradiol concentrations. Fifty-five pairs of ovaries were collected (32 of which were at five distinct stages of the cycle) from adult marmosets, and antral follicles were manually excised and separated into four size groups. Daily urinary FSH and plasma estradiol and progesterone concentrations from Day 0 of the follicular phase to 2 days postovulation were measured in 22 marmosets using enzyme immunoassays. The FSH profile revealed two distinct peaks, on Days 2 and 6, during the 10-day follicular phase, with a marginal periovulatory increase on Days 9 and 10. Estradiol levels rose significantly (P: < 0.05) above baseline (Days 1-4) on Day 5 and continuously increased to a peak on the day preceding ovulation (Days 8 and 9). Follicle dissection revealed a high (mean = 68) and variable (range, 14-158) total number of antral follicles >0.6 mm. The number of antral follicles significantly declined (P: < 0.001) with age. The number of preovulatory follicles (>2 mm) was positively correlated with the number of antral follicles (P: < 0. 001) and tended to be negatively related to age (P: = 0.06). The number of antral follicles did not vary significantly with stage of the ovarian cycle, although the follicle size distribution was cycle-stage dependent (P: < 0.05). Follicles >1.0 mm appeared only in the follicular phase, and preovulatory follicles (>2.0 mm) appeared only at the end of the follicular phase (Days 7-9). The Day 2 FSH peak corresponded to emergence of a population of medium-size antral follicles, and the Day 6 peak was consistent with rising estradiol levels and appearance of the preovulatory follicles. These results suggest that some aspects of marmoset folliculogenesis are comparable to those in Old World primates, including the absence of multiple follicular waves and the appearance of an identifiable dominant follicle in the midfollicular phase. However, the midphase FSH peak, multiple dominant follicles, and abundance of nonovulatory antral follicles differ strongly from the pattern in Old World primates and humans. The findings are discussed in relation to the regulation of growth of multiple ovulatory follicles and provide the basis for further studies on factors influencing the dynamics of follicular growth and development in this species.     

Ovarian prostaglandin endoperoxide synthase: cellular localization during the rat estrous cycle

The specific cellular localization of prostaglandin endoperoxide (PGH) synthase was studied throughout the rat estrous cycle. Animals were necropsied at 1300 h on each day of the 4-day cycle, and an additional group was necropsied at 2300 h on proestrus. Ovaries were removed and processed for cellular identification of PGH synthase by immunohistochemistry. At all stages of the cycle, intense immunostaining was observed in newly formed corpora lutea. Luteal cells were immunoreactive, but the connective tissue centrum was unstained. Interstitial tissue contained heavily labeled cells, whereas the germinal epithelium exhibited faint staining. During estrus, metestrus, and diestrus, thecal cells from preantral and antral follicles contained PGH synthase immunoreactivity, but granulosa cells were unstained. Faint staining of mural granulosa cells was observed first in 78% of preovulatory follicles (less than 400-microns diameter) in ovaries collected on the afternoon of proestrus. After the luteinizing hormone surge, 95% of the preovulatory follicles exhibited PGH synthase staining. The percentage of immunoreactive granulosa cells in these preovulatory follicles increased 4-fold in ovaries collected at 2300 h on proestrus. The presence of ovarian PGH synthase throughout the rat estrous cycle and the changes in cellular localization may reflect the potential role of PGs in follicular and luteal function.     

Histology,histochemistry and morphometry of the ovary of the adult plains viscacha (Lagostomus maximus) in different reproductive stages

Lagostomus maximus is a South American Hystricognathi rodent whose reproductive behaviour shows characteristics unusual for mammals, such as polyovulation (200–800 oocytes) and a high rate of embryo mortality. Thirty‐six mature females captured in the province of Buenos Aires showed different physiological reproductive stages. Most of them presented a postpartum oestrus in August–September. This characteristic is different from that reported in other geographical areas. The stages considered were: anoestrus, follicular phase, early pregnancy and late pregnancy. The ovaries were light‐pink and smooth and presented a tortuous cord‐like aspect. Many primordial follicles were found in all the females studied. Follicles in different states of maturation and primary and accessory corpora lutea were observed in the cortex. These structures were smaller than those present in other related species. Follicles did not project into the surface of the organ. Calcified follicles of diverse size were found in all the ovaries. Atretic follicles were found in all the stages analysed. Interstitial tissue surrounding the follicles and the corpora lutea was also observed. The number and proportion of different cortical structures varied in the physiological stages analysed. The ovaries of the viscacha have differential characteristics in comparison to other Hystricognathi, some of them related to polyovulation.