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Differences in Visual Attention Patterns to Sexually Mature and Immature Stimuli Between Heterosexual Sexual Offenders, Nonsexual. For some species of spiders, mating comes with a deadly risk — the possibility of being eaten by their much larger female partner.​ But in two species of widow spiders — the venomous spider group that includes black widows — males deploy an ingenious strategy to avoid being. Assessment of Age, Sex, and Height from Immature Human Bones. Br Med J ; 1 doi: kwansei.info (Published 18 January )​.

Young, single men are fed up with being typecast as immature, insensitive and sex-obsessed, with a survey finding that the majority believe in. Zoolog Sci. Mar;21(3) Sex inversion of sexually immature honeycomb grouper (Epinephelus merra) by aromatase inhibitor. Bhandari RK(1)​. Differences in Visual Attention Patterns to Sexually Mature and Immature Stimuli Between Heterosexual Sexual Offenders, Nonsexual.

Zoolog Sci. Mar;21(3) Sex inversion of sexually immature honeycomb grouper (Epinephelus merra) by aromatase inhibitor. Bhandari RK(1)​. Assessment of Age, Sex, and Height from Immature Human Bones. Br Med J ; 1 doi: kwansei.info (Published 18 January )​. Differences in Visual Attention Patterns to Sexually Mature and Immature Stimuli Between Heterosexual Sexual Offenders, Nonsexual.






For some species of spiders, sex comes with sex deadly risk — the possibility of immature eaten by their much sxe female partner. But in two species of widow spiders — the venomous spider group that includes black widows — males deploy an ingenious strategy to avoid being cannibalized during sex, according to a new study. Scientists immaturf discovered that widow spider sex Latrodectus hasselti and Latrodectus geometricus prefer to mate with females that are not yet sexually mature but which still have internal immature that are capable of storing sperm, which the males access by piercing the female's exoskeleton.

This sexual sneak attack is a win-win situation for the male. He literally plants the seeds to successfully fertilize the female at a later date, and is able se scuttle sex from the encounter with his dignity — and his head — intact. Sexual cannibalism is common in widow spiders, but males mating with immature females to avoid being cannibalized is behavior immature was previously unheard of, the researchers wrote in a new study. Study co-author Maydianne C.

Andrade, a professor in the Department of Biological Sex at the University of Toronto, Scarborough, has studied widow spiders for nearly two decades, but had never observed this behavior until recently.

She told Live Science in an sex that it was first brought to her attention immature a member of her immature team — M. Daniella Biaggio, the study's lead author. Biaggio reported that not only were the males mounting immature females, but they were also difficult to separate from their partners.

Once the scientists realized that the spiders were sexthey isolated the females and later found that their eggs had been successfully fertilized, noting in sex study immature the females molted normally and subsequently produced offspring, even though sex had not mated as adults. Andrade explained that se she sex her preliminary findings at a conference, she was approached sex another scientist, Yael Lubin from Ben-Gurion University of the Negev, whose doctoral students Iara Sandomirsky and Ally R.

Harari had observed similar behavior in widow spiders. Sex researchers decided to combine their efforts in a new study investigating the activity that had been hiding in plain sight. This mating strategy is challenging for males — the window of opportunity for finding a female that has recently developed her sperm-storing receptacles but is not yet sexually mature is small, Andrade explained.

And there is still much to be learned: How the males even find the aex females, which immature produce the signature "come hither" pheromones that mature females emit; what the immature cost is immature females that are fertilized before they're sexually mature; and how widespread this behavior is immature not just in widows, immature in other sexually cannibalistic spider species as well.

The findings were published online Sept. Original article on Live Science. Live Science. An adult female redback spider Latrodectus hasselti with a dead male near her immature.

Daniella Biaggio, the study's lead author. Biaggio reported that not only were the males mounting immature females, but they were also difficult to separate from their partners. Once the scientists realized that the spiders were mating , they isolated the females and later found that their eggs had been successfully fertilized, noting in the study that the females molted normally and subsequently produced offspring, even though they had not mated as adults.

Andrade explained that after she presented her preliminary findings at a conference, she was approached by another scientist, Yael Lubin from Ben-Gurion University of the Negev, whose doctoral students Iara Sandomirsky and Ally R. Harari had observed similar behavior in widow spiders.

The researchers decided to combine their efforts in a new study investigating the activity that had been hiding in plain sight. This mating strategy is challenging for males — the window of opportunity for finding a female that has recently developed her sperm-storing receptacles but is not yet sexually mature is small, Andrade explained.

And there is still much to be learned: How the males even find the immature females, which don't produce the signature "come hither" pheromones that mature females emit; what the physical cost is to females that are fertilized before they're sexually mature; and how widespread this behavior is — not just in widows, but in other sexually cannibalistic spider species as well.

The findings were published online Sept. Original article on Live Science. Next, to clarify the cause of recovery after sex change, we analyzed the expression patterns of steroidogenic enzymes in the gonads of MT-treated and control fish during precocious sex change; serum sex hormone levels were also examined.

Specimens of E. The fish were maintained as described previously [ 28 ]. We believe that they reach sexual maturity as females approximately 5 yr after hatching and change their sex from female to male more than 10 yr after hatching. After air-drying overnight, the feed was stored at room temperature until used for feeding.

All fish were anesthetized with 0. After measurements of total length and body weight, the fish were euthanized by decapitation. All animal handling and experimental procedures were conducted in accordance with our guide for the care and use of laboratory animals Animal-jikken-kisoku For initial controls, seven fish were euthanized, and their gonads were collected to determine the gonadal status before the start of the treatment.

Fish were fed once daily at the rate of 0. At 1, 2, 3, 5, and 7 mo after the start of treatment, 6 to 10 fish from each group were euthanized, and their gonads and blood were collected to examine the effects of MT on the gonads and steroid hormone levels.

Then, at 1, 3, and 6 mo after the withdrawal of treatment, four to six fish from each group were euthanized, and their gonads and blood were collected. An overview of the experimental design is shown in Figure 1. Control and MT-treated fish were kept in actively aerated seawater in 1.

The gonads were fixed in Bouin solution, embedded in paraffin, cross-sectioned, and stained with Delafield hematoxylin. Standard methods for light microscopy were used. The expression of three steroidogenic enzymes Cyp11a, Cyp19a1a, and Cyp11b in the gonads was examined at the end of the 7-mo treatment. The method was as described by Murata et al. The method was as described previously by Asahina et al. The size, age, growth performance, and gonadal status of fish during the experimental period are summarized in Table 1.

All fish in the initial control group had immature ovaries consisting of the ovarian cavity and a few oogonia Fig. As the experiment progressed, the immature ovaries of all control fish developed slowly as described in our previous study [ 28 ], and perinucleolar stage oocytes were detected in the ovary at the end of the experiment Fig.

Conversely, 2 mo after the start of the experiment, the slit efferent duct-like structure appeared between the ovarian cavity and blood vessel on the dorsal side in the gonads of all MT-treated fish, and spermatocytes were first detected in the gonads of some MT-treated fish, indicating the onset of spermatogenesis Fig. Spermatozoa in the gonads of almost all MT-treated fish disappeared within 1 mo after the withdrawal of MT treatment Fig.

At 3 and 6 mo after the withdrawal of MT treatment, neither sperm nor spermatogenesis was detected in the gonads of any MT-treated fish, and perinucleolar oocytes were seen in the gonads of some MT-treated fish as in control fish Fig.

Sterile gonads consisted of somatic cells only; no germ cells could be observed in these sterile, MT-treated fish during the last 5 mo of the experiment data not shown. Histological analysis of the gonads of E. A Initial control immature ovary. C and E The MT-treated gonads 2 and 7 mo after the start of the experiment. Inset shows high magnification of sperm. G and I Gonads 1 and 6 mo after the withdrawal of MT treatment. Overview of the size and gonadal status of E. To clarify the effects of MT on the expression of steroidogenic enzymes, we used immunohistochemistry to investigate the expression pattern of three steroidogenic enzymes Cyp11a, the key steroidogenic enzyme; Cyp19a1a, which is essential for E2 production; and Cyp11b, which is important for fish-specific androgen 11KT production in the gonads of the Malabar grouper 7 mo after the start of the experiment.

In the control immature ovary, Cyp11a-positive cells appeared in the area surrounding germ cells and in the ovarian tunica area, Cyp19a1a-positive cells appeared only in the somatic cells surrounding germ cells, and Cyp11b-positive cells appeared only in the ovarian tunica area Fig.

These steroidogenic enzyme-positive cells were also detected in MT-treated testes. Cyp11a-positive cells appeared in the somatic cells surrounding germ cells and cysts, Sertoli cell layer, and somatic tissue in the ovarian tunica area Fig. Cyp19a1a-positive cells appeared only in the somatic cells surrounding germ cells and cysts Fig.

Cyp11b-positive cells appeared only in the somatic tissue in the ovarian tunica area. Cyp11b-positive cells were not localized in the interstitial tissue of testes Fig. Immunohistochemical analysis of the gonads of E. Arrows indicate positive signals. Serum steroid levels E2 and 11KT of fish 7 mo after the start of the experiment.

Numbers in the figure indicate total number of fish sample. However, after the withdrawal of MT treatment, spermatogenesis in testes immediately stopped and disappeared, and testes ultimately changed back to immature ovaries with some perinucleolar oocytes. This result indicates that precocious sex change in underyearling Malabar grouper via oral MT treatment is impermanent.

To date, this is the first study in the peer-reviewed literature demonstrating the recovery of sex-reversed testes to ovaries after the withdrawal of MT treatment in the grouper. On the other hand, MT treatment in mature female grouper is well known to induce permanent artificial sex change from female to male [ 8 — 17 ].

In mature female Malabar grouper older than 10 yr , we also have successfully induced permanent sex change from female to male by MT injection and obtained fertilized eggs, indicating complete sex change [ 31 ]. Thus, in the grouper species MT treatment could not induce permanent sex change in immature females, but permanent sex reversal from female to male was induced in mature females.

These results suggest that the effect of MT treatment varies with age, size, and degree of sexual maturation. We predicted that differences in the physiological response to exogenous androgen exist between immature and mature ovaries in grouper. Recent studies [ 7 , 23 , 24 , 27 ] have revealed the endocrine mechanism of natural sex change in the protogynous honeycomb grouper, Epinephelus merra.

In this species, Cyp11a-immunopositive and Cyp11b-immunopositive cells appear in the remaining follicle layer of degenerated oocytes in the gonads during the early phase of sex change.

During the male phase, these Cyp11a-immunopositive and Cyp11b-immunopositive cells differentiate into Leydig cells in the interstitial tissue of testes.

Moreover, correlated with Leydig cell differentiation, serum 11KT level increases significantly during natural and hormone-induced sex change from female to male. It is also known that Cyp19a1a protein expression in the gonads is decreased during natural sex change from ovary to testes in the honeycomb grouper Murata, Kobayashi, and Nakamura, unpublished results.

In the protogynous hermaphrodite red-spotted grouper, Epinephelus akaara , and the orange-spotted grouper, Epinephelus coioides , Cyp19a1a protein or mRNA expression in the follicle layer cells in the gonads reportedly drops significantly during artificial permanent sex reversal from female to male induced by MT treatment [ 25 , 26 ].

In other sex-changing fish, the endocrine pathway of sex steroid hormone synthesis reportedly changed in accordance with gonadal sex change [ 32 — 35 ]. These studies have indicated that endocrine functional sex change in somatic cells is one of the critical events in permanent sex change from ovary to testes in sex-reversing fish.

In the present study, we immunohistochemically analyzed the expression pattern of three steroidogenic enzymes Cyp11a, Cyp19a1a, and Cyp11b in the gonads of experimental Malabar grouper. The expression patterns of these steroidogenic enzymes were almost the same as those in the ovaries of control fish.

Moreover, no differences were observed in serum steroid levels of E2 and 11KT between control and MT-treated fish. These results were not harmonious with the above reports. From these results, we concluded that in the case of immature Malabar grouper MT might have little effect on endogenous steroidogenesis in the gonads, suggesting that precocious sex change from immature ovary to testis by MT treatment in underyearling Malabar grouper might occur only through direct stimulus of germ cells for spermatogenesis by the exogenous androgen MT treatment.

We believe that the effect, if any, exerted by MT treatment on the endogenous steroidogenesis was miniscule and insufficient to maintain the gonads as testes. We presumed, therefore, that spermatogenesis immediately stopped after the withdrawal of MT treatment.

Moreover, the results suggested that, because the somatic cells in the gonads still had ovarian endocrine function, germ cells differentiated into oocytes again.

Our previous study [ 27 ] demonstrated that gonadotropins in the pituitary, especially follicle-stimulating hormone FSH , have a critical role in initiating sex change and in maintaining the testes in the protogynous honeycomb grouper. On the basis of our study, we predicted that FSH in the case of the Malabar grouper is also essential for the maintenance of the testes after sex change.

However, whether MT had effects on the expression pattern of gonadotropins in the pituitary was not investigated in the present study. Recently, we cloned gonadotropin hormone subunit genes cga , fshb , and lhb and established a real-time RT-PCR assay system in the Malabar grouper [ 36 ]. Further studies are needed to analyze the effect of MT on the expression patterns of gonadotropins in the pituitary in order to clarify the cause of precocious sex change recovery with MT treatment in immature grouper.

In this study, although the progression of gonadal developmental was similar to that observed in our previous reports on gonadal sex differentiation in the Malabar grouper, the growth performance of fish was lower than that previous observed [ 28 ].

This might have been caused by the change in the density of fish in the experimental tank after the withdrawal of MT treatment. It has been reported previously that sterile gonads were observed in MT-treated salmonid fish, but the physiological mechanism remains unclear [ 37 ].

Similarly, the physiological mechanism of the phenomenon observed in this study is also unclear. Therefore, detailed studies are required to clarify this mechanism and better understand the process of precocious sex change using artificial androgen in the grouper. Oxford University Press is a department of the University of Oxford.