Distribution by sex of mouse fetuses in the intrauterine position

We examined whether or not the sex of the fetuses of polytocous animals distributes randomly in the position along the uterine horn in 255 mouse litters. The fetal sex ratio did not differ significantly among the three intrauterine segments (ovarian, middle, and cervical). Based on the number of fetuses examined in this study, it can be stated that even if sex ratio differences exist among the segments, the ratio in individual segments would fall mostly inside the ±0.1 range, when the overall sex ratio (M/(M+F)) is around 0.5.     

Genome‐wide association study for semen traits of the bulls in Chinese Holstein

A genome‐wide association study (GWAS) was performed to identify markers and candidate genes for five semen traits in the Holstein bull population in China. The analyzed dataset consisted of records from 692 bulls from eight bull stations; each bull was genotyped using the Illumina BovineSNP50 BeadChip. Association tests between each trait and the 41 188 informative high‐quality SNPs were achieved with gapit software. In total, 19 suggestive significant SNPs, partly located within the reported QTL regions or within or close to the reported candidate genes, associated with five semen traits were detected. By combining our GWAS results with the biological functions of these genes, eight novel promising candidate genes, including ETNK1, PDE3A, PDGFRB, CSF1R, WT1, DSCAML1, SOD1 and RUNX2, were identified that potentially relate to semen traits. Our findings may provide a basis for further research on the genetic mechanism of semen traits and marker‐assisted selection of such traits in Holstein bulls.     

Sons are made from old stores: sperm storage effects on sex ratio in a lizard

Sperm storage is a widespread phenomenon across taxa and mating systems but its consequences for central fitness parameters, such as sex ratios, has rarely been investigated. In Australian painted dragon lizards (Ctenophorus pictus), we describe elsewhere that male reproductive success via sperm competition is largely an effect of sperm storage. That is, sperm being stored in the female reproductive tract out-compete more recently inseminated sperm in subsequent ovarian cycles. Here we look at the consequences of such sperm storage for sex allocation in the same species, which has genetic sex determination. We show that stored sperm have a 23% higher probability of producing sons than daughters. Thus, shifts in sex ratio, for example over the reproductive season, can partly be explained by different survival of son-producing sperm or some unidentified female mechanism taking effect during prolonged storage.     

Flow sorting of X and Y chromosome-bearing mammalian sperm: Activation and pronuclear development of sorted bull,boar, and ram sperm microinjected into hamster oocytes

Flow cytometric techniques were used to measure relative DNA content of X and Y chromosome-bearing bull, boar, and ram sperm populations and to separate the two sex-determining populations. Neat semen was prepared for flow cytometric analysis by washing, light sonication, and staining with 9 μM Hoechst 33342. Computer analysis of the bimodal histograms showed mean X-Y DNA differences of 3.9, 3.7, and 4.2% for bull, boar, and ram, respectively. Flow cytometric reanalysis of sorted bull, boar, and ram sperm showed purities greater than 90%. Bull, boar, and ram sperm nuclei were microinjected into hamster oocytes. Microinjected sperm were either unsorted, sorted, unsorted plus dithio-threitol (DTT) exposure, or sorted plus DTT exposure. Following microinjection, eggs were incubated 3 hr, fixed, and stained. A total of 579 eggs was observed for sperm activation (decondensation or formation of a male pronucleus). A lower percentage of sorted than unsorted (3 vs. 23%) boar sperm was activated (P <.05). However, sorted and unsorted DTT-exposed boar sperm or sorted and unsorted bull or ram sperm, regardless of DTT treatment, did not differ significantly. Sorted sperm nuclei of both rams and bulls exhibited higher activation rates than sorted boar sperm (P <.05). Treatment of sperm with DTT increased the activation rate (P < .05) for sorted boar sperm but not for bull or ram sperm. These data represent the first separation of bull, boar, and ram X and Y chromosome-bearing sperm populations and the first evidence that sperm of domestic animals sorted on the basis of DNA by flow cytometric procedures have the ability to decondense and to form pronuclei upon injection into a hamster egg.     

Sociocultural aspects of disorders of sex development

Disorders of sex development (DSD) is a congenital condition in which the development of chromosomes, gonads, hormones, and reproductive structures are atypical. DSD brings with it a psychological impact on the affected individual and their families. The consensus statement on management of DSD strongly advised an integrated and multidisciplinary approach in providing care to the affected individuals. Studies have been conducted focusing on medical intervention, and more recently, there is increasing attention paid to psychological aspects of DSD. However, studies reporting cultural aspects of DSD are lacking. This review provides an overview on how culture impacts the affected individuals in coping with DSD and making decisions with regard to gender assignment or reassignment, help‐seeking behavior for medical treatments, attitudes toward medical treatment, religious beliefs, and values concerning marriage and fertility. The involvement of social scientists is needed to study sociocultural aspects of DSD from more diverse cultures, to help affected individuals and their families in gaining better social acceptance. Birth Defects Research (Part C) 108:380–383, 2016. © 2016 Wiley Periodicals, Inc.     

Why boys will be boys and girls will be girls: Human sex development and its defects

Among the most defining events of an individual's life, is the development of a human embryo into male or a female. The phenotypic sex of an individual depends on the type of gonad that develops in the embryo, a process which itself is determined by the genetic setting of the individual. The development of the gonads is different from any other organ, as they possess the potential to differentiate into two functionally distinct organs, testes, or ovaries. Sex development can be divided into two distinctive processes, “sex determination,” which is the commitment of the undifferentiated gonad into either a testis or an ovary, a process that is genetically programmed in a critically timed manner and “sex differentiation,” which takes place through hormones produced by the gonads, once the developmental sex determination decision has been made. Disruption of any of the genes involved in either the testicular or ovarian development pathway could lead to disorders of sex development. In this review, we provide an insight into the factors important for sex determination, their antagonistic actions and whenever possible, references on the “prismatic” clinical cases are given. Birth Defects Research (Part C) 108:365–379, 2016. © 2016 Wiley Periodicals, Inc.     

Rhesus macaque blastocysts resulting from intracytoplasmic sperm injection of vacuum‐dried spermatozoa*

Background Sperm desiccation is an attractive approach for sperm preservation. In this study, we examined the feasibility and efficiency of intracytoplasmic sperm injection using vacuum‐dried rhesus macaque sperm in CZB medium supplemented with 10% fetal bovine serum. Methods A total of 109 MII oocytes were injected with 69 fresh ejaculated sperm and 40 vacuum‐dried sperm. Results Cleavage occurred in 97% of oocytes injected with fresh, motile sperm and in 88% of oocytes injected with vacuum‐dried sperm. Of the cleaved oocytes, 68% fresh sperm‐injected oocytes and 74% of dried sperm‐injected oocytes developed to the compact morula stage. Blastocyst development was comparable between fresh‐injected (16%) and vacuum‐dried‐injected (17%) oocytes. Differences between treatment groups were not significant. Transmission electron microscopic observation of the blastocysts indicated no detectable differences between fresh sperm and dried sperm‐derived embryos. Conclusions We conclude that vacuum‐dried rhesus macaque sperm are capable of inducing fertilization and development of pre‐implantation embryos when sperm were dried under vacuum and microinjected into normal viable oocytes.     

早期胚胎的发育选择:性别决定

性别决定是一个复杂的发育调控过程, 早期胚胎发育过程中, 雌雄二者必居其一的发育选择是胚胎性腺形成必须的发育决定。文章综述了动物性别决定的遗传系统、性腺发生、性别决定关键基因及其作用机制, 从分子进化的角度分析了性染色体与性别决定形成机制, 提示性别决定基因在进化中总是趋向异配性染色体。     

Growth, gonadal development and sex ratios of meiogynogenetic diploid sea bass

Gynogenesis showed little effect on general physiology and gonadal development in sea bass Dicentrarchus labrax . Meiogynogenetic fish showed well-developed gonads indicating low occurrence of developmental imbalances even after gynogenesis induction in this species. In addition, the proportion of sexes of meiogynogenetic sea bass was similar to the diploid controls in two independent trials, which did not deviate significantly from a 1:1 male: female sex ratio. Even considering some environmental influence on sex differentiation, as has been previously demonstrated, the fact that the proportion of sexes was similar between gynogenetic and control diploids essentially eliminates the possibility that in the sea bass the females are the homogametic sex. Although the mechanism of sex determination of this species still remains unknown, even after gynogenesis induction, the genetic mechanism of the ZW/ZZ type could probably operate in the sea bass.     

Correlation of housefly sex pheromone production with ovarian development

Pheromone production in the housefly was monitored during oögenesis and in ovariectomized insects by gas-liquid chromatography (GLC) and radio-GLC. The presence of vitellogenic ovaries was required for the initiation of (Z)-9-tricosene (muscalure), (Z)-9,10-epoxytricosane and (Z)-14-tricosen-10-one synthesis. Methylalkane synthesis was enhanced by developing ovaries. Insects ovariectomized within 12 hr after emergence produced no detectable amounts of (Z)-9-tricosene, C₂₃ epoxide nor C₂₃ ketone and synthesized less methylalkanes than the controls. This effect was reversed by ovary implants. When flies were ovariectomized after oviposition, synthesis of (Z)-9-tricosene, C₂₃ epoxide and C₂₃ ketone continued. Thus, initiation of the synthesis of these C₂₃ pheromone compounds required a vitellogenic ovary, but the ovary was not required to maintain synthesis.     

A histological description of gonadal development and sex differentiation in the coho salmon (Oncorhynchus kisutch) for both untreated and oestradiol immersed fry

Gonadal development is described in detail for coho salmon ( Oncorhynchus kisutch ) between hatching and 1000 degree-days, post-hatch, to aid sex reversal research. Germ cell morphology and sequence, vascular and reproductive duct development, and gross characteristics of the gonads are presented. Sex differentiation occurs by 380 degree-days, post-hatch (800 degree-days, post-fertilization) and is direct to male and female. Oocytes proliferate rapidly after differentiation while the testes enter a period of quiescence. Fry immersed for short durations in oestradiol (200 μg ⁻¹) are also examined. Hormone immersion advanced sex differentiation by 70 degree-days. The immersions were applied early, at 20 and 90 degree-days, post-hatch, yet still altered the sex ratio and timing of differentiation. Definitive germ cells, which are abundant during this period, may be the type most receptive to steroid treatment.     

Rapid chiral separation methods development by cyclodextrin-mediated capillary electrophoresis for acidic and basic compounds

Chiral separation methods development using conventional techniques such as GC or HPLC requires a lot of experience, effort, and expense, due to the wide diversity of the optically active solutes and their possible chiral selectors. Capillary electrophoresis has received increased attention as an alternative technique for chiral separation due to its inherent high efficiencies and ease of methods development. However, due to the wide variety of chiral selectors available in CE, the benefits of this technique might be diminished without an appropriate methods development scheme. In this paper detailed examples are shown for fast, efficient, and predictable chiral capillary electrophoresis separation methods development based on a new and systematic theory. Optimized separations and their parameters are presented for several enantiomeric acids and bases. All the three possible cases, such as the use of low and high pH, as well as pH = pK buffer systems are thoroughly discussed. © 1995 Wiley-Liss, Inc.     

Gonadal development and sex steroids in a female Arctic charr broodstock

Gonadal development and plasma levels of sex steroids were investigated in female Arctic charr at 3-week intervals over a 12-month period. Circulating levels of oestradiol-17β (E₂), testosterone (T) and 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) were measured by radioimmunoassay, and gonadal status assessed through histological examination and measurement of gonadosomatic index (GSI) and frequency distribution of oocyte size-classes. Gonadal recrudescence during March-July was characterized by modest but insignificant increases in plasma levels of E₂ (2–4 ng ml^?1) and T (2–5 ng ml^?1) and recruitment of oocytes into yolk accumulation. Only a small and insignificant rise in GSI and no apparent increase in oocyte diameter occurred during this period, indicating that the rate of yolk formation and oocyte growth was low. Following transformation from stage V (peripheral yolk granule stage) to stage VI (yolk granule migration stage) in late July, the vitellogenic oocytes entered a phase of rapid growth which resulted in a marked rise in GSI until ovulation commenced in late September. Gonadal growth during this period was accompanied by increases in plasma levels of E₂ and T which peaked at 11 ± 1 (mid-August) and 71 ± 5ng ml^?1 (late September), respectively. The levels of both steroids dropped rapidly during final maturation and ovulation, followed by a surge in plasma levels of 17,20β-P which peaked at an average of 74 ± 17 ng ml^?1 in early October. All three steroids returned to basal levels within a month after ovulation, and all steroids, except E₂, remained low until March of the following year. A slight increase in E₂ detected in February and March during the second season may have been associated with recruitment into vitellogenesis of a new generation of oocytes. It is suggested that the abrupt increase in vitellogenesis in late July may reflect a condition-dependent decision to proceed with maturation, once the energy reserves have been repleted during spring-early summer.     

Sperm separation attempts via the use of albumin gradients in rabbits

The objective of this study was to evaluate the sedimentation method using albumin gradients to determine whether it could help pre-select sex in rabbits. Of the 21 litters produced during natural mating, the sex ratio was 52.8% males which did not differ (P>0.05) from 55.3% males (nine litters) produced via AI from semen recovered after sedimentation through albumin gradients. The results obtained in this study are consistent with some but not all previous data. The quality of the recovered spermatozoa improved (P<0.05) when compared to those in the whole ejaculate. The sex ratio results obtained in this study suggest that sedimentation methods via the use of albumin gradients may not be effective for separating X and Y spermatozoa. Furthermore, actual sex ratio data should be stressed in all future studies with X and Y sperm separation, in addition to the $\text{in}$$\text{vitro}$ data generated.     

Evaluating reasons for biased sex ratios in Crustacea

ABSTRACT

While equal ratios of males and females are normal, crustacean sex ratios are frequently biased. Here I review potential reasons for sex ratio biases in animals, and evaluate how likely they apply to crustaceans. I introduce crustacean examples and highlight promising crustacean taxa for future studies where examples are lacking. I conclude that ecological differences between the sexes appear to be the dominant reason for sex ratio bias in crustaceans. Major life history patterns limit the importance of evolutionary drivers to sedentary taxa with limited dispersal. Still largely unresolved is the question whether females can bias their offspring sex ratio, and given the diversity of sex determining systems, answers will vary from case to case.

Abbreviations: LMC: local mate competition; LSC: local sperm competition.     

Gender role behavior in children with XY karyotype and disorders of sex development

Children exhibit gender-typical preferences in play, toys, activities and interests, and playmates. Several studies suggest that high concentrations of pre- and postnatal androgens contribute to male-typical behavior development, whereas female-typical behavior develops in the absence of high androgens levels. This study aims to explore the consequences of hypoandrogenization on gender-typical behavior in children who have an XY karyotype and disorder of sex development (DSD). Participants included 33 children (ages 2-12 years) with an XY karyotype and DSD; 21 reared as girls and 12 reared as boys. Children's preferred activities and interests and playmate preferences were assessed with parent report questionnaires, a structured free-play task, and choice of a toy to keep as a gift. Participant's responses were compared to those of children recruited in a pre-school and elementary school survey (N=166). In this study, the degree of hypoandrogenization as indicated by genital stage and diagnosis showed a significant relationship to nearly all of the gender-related behaviors assessed, supporting the hypothesis that masculinization of gender role behavior is a function of prenatal androgen exposure. Despite the fact that children with partial androgen effects reared as girls showed increased "boyish" behaviors, they did not show increased signs of gender identity confusion or instability on a group level. We conclude that androgen exposure plays a decisive role in the development of gender-typical behavior in children with XY karyotype and DSD conditions.     

Challenges in the diagnosis and management of disorders of sex development

Disorders of sex development (DSD) represent a spectrum of uncommon but very complex disorders with medical, psychosexual, and family implications for those affected by them. The diagnosis and management of these disorders requires a coordinated team of multiple specialists. Following an international conference in Chicago in 2005, a consensus statement was created and presented, which has resulted in a new paradigm in the nomenclature, classification, and management of DSDs. Since that time, many improvements have been forthcoming, most notably in the area of molecular genetic technologies. These developments have advanced our understanding of the specific etiologies underlying many of these conditions. In this article, we present an overview of the physiology of sex development, a few clinical vignettes highlighting specific pathologic conditions, discussions regarding the evaluation and management of these disorders, and some thoughts on future directions in this field. Birth Defects Research (Part C) 108:293–308, 2016. © 2016 Wiley Periodicals, Inc.     

The effect of cryptic female choice on sex allocation in simultaneous hermaphrodites

Sex allocation theory for simultaneous hermaphrodites has focused primarily on the effects of sperm competition, but the role of mate choice has so far been neglected. We present a model to study the coevolution of cryptic female choice and sex allocation in simultaneous hermaphrodites. We show that the mechanism of cryptic female choice has a strong effect on the evolutionary outcome: if individuals remove a fixed proportion of less-preferred sperm, the optimal sex allocation is more female biased (i.e. more biased towards egg production) than without cryptic female choice; conversely, if a fixed amount of sperm is removed, sex allocation is less female-biased than without cryptic female choice, and can easily become male biased (i.e. biased towards sperm production). Under male-biased sex allocation, hermaphroditism can become unstable and the population can split into pure males and hermaphrodites with a female-biased allocation. We discuss the idea that the evolution of sex allocation may depend on the outcome of sexual conflict over the fate of received sperm: the sperm donor may attempt to manipulate or by-pass cryptic female choice and the sperm recipient is expected to resist such manipulation. We conclude that cryptic female choice can have a strong influence on sex allocation in simultaneous hermaphrodites and strongly encourage empirical work on this question.     

Apyrene sperm from the triploid donors restore fecundity of cryopreserved semen in Bombyx mori

Female moths of Bombyx mori were artificially inseminated with cryopreserved semen. The fertility of inseminated females varied from 0% to 76.9% depending on the strain. Addition of fresh semen from triploid males, which are infertile but whose semen includes intact apyrene sperm, greatly improved fecundity of cryopreserved semen from normal males. Frozen apyrene sperm from the triploid donors also improved the fecundity of females, inseminated with cryopreserved normal semen, but less than fresh semen from triploid males. Fertilization success in B. mori requires the presence of both, intact eupyrene and apyrene sperm. Our results show that eupyrene sperm tolerate the cryopreservation process better than apyrene sperm. Hence, we recommend to add apyrene sperm from the triploid donors as helper sperm routinely to cryopreserved semen in artificial insemination. This may advance the application of cryopreservation as a routine technique to maintain silkworm resources. The technique may also be applicable to other moth and butterfly species which, like B. mori, possess eupyrene and apyrene sperm.