Advantages of Epoxy Resin as a Mounting Medium for Light Microscopy

The need for very durable mounting is especially felt in the teaching of parasitology and mycology; otherwise, the availability of microscope slides may depend on the use of fresh specimens. Resinous mounts and those in aqueous media sealed with fingernail lacquer, paraffin or asphalt do not preserve specimens satisfactorily. Polyvinylpyrrolidone (pvp), a water-soluble mounting medium described by Burstone (1962), cannot be applied directly for mounting of insects and certain other parasites which have water-repelling integuments; moreover, pvp bleaches eosin. Grimley et al. (1965) prepared large epoxy sections of tissues from which areas for electron microscopy could be selected. This procedure however is designed for electron microscopic techniques whereas the present paper describes a direct epoxy mounting method to produce permanent mounts for light microscopy.     

A Modified Technic for Salivary-Gland Chromosomes

This technic was worked out for making permanent mounts of salivary-gland squashes of strains and species of Drosophilidae, which yield material difficult to work with. It includes a prior fixation in a modified Carnoy's fluid, staining in solutions of orcein in 60% or 70% acetic acid, part dehydration in the vapor and liquid of a 95% solution of alcohol, and direct mounting in Euparal by means of the drainage-method.     

Mounting behavior in pregnant and pseudopregnant female rats

Mounting behavior by female rats with regular 4-day estrous cycles was significantly reduced after the induction of pregnancy, pseudopregnancy, or treatment with progesterone. The mounting behavior shown by pseudopregnant female rats was comparable to that shown by ovariectomized females. Pseudopregnant and unmated females showed mounts with pelvic thrusting with the same frequency after treatment with estradiol benzoate (EB). EB stimulated the display of mounts with pelvic thrusting in ovariectomized females, and this behavior was not affected by concurrent progesterone treatment. It is suggested that the reduction of mounting in pregnant and pseudopregnant female rats is due to decreased ovarian estrogen secretion.     

Device to facilitate freeze-drying specimens for scanning electron microscopy.

Thin specimens such as tissue culture monolayers were freeze-dried in a vacuum evaporator without thawing by using a 13 mm thick aluminum disk cooled with liquid nitrogen just prior to processing. This disk, 95 mm in diameter, easily accommodated 18 specimens suitable for mounting on 12.5 mm specimen mounts. The specimens were gold coated immediately after drying without breaking the vacuum thereby saving the time usually needed for a second evacuation. Vero cells processed in this way displayed their delicate surface structures.     

Male Post‐Ejaculatory Mounting in the Ring‐Tailed Lemur (Lemur catta): A Behavior Solicited by Females?

Male mate guarding can take many forms but often involves aggression toward male conspecifics and continued proximity with a female. This study describes a previously undocumented behavior in a promiscuous primate, the ring‐tailed lemur: post‐ejaculatory (PE) mounting. PE mounting was documented across eight mating seasons in a ring‐tailed lemur colony on St. Catherines Island (SCI), USA. During PE mounting, a male remounts a female following ejaculation and clasps her midsection as if to mate again, but copulation does not occur; males showing this behavior typically lack erections, and their mounts show an absence of penile intromission and rhythmic thrusting. Male PE mounting was more common among males mating earlier in the queue, and when PE mounting occurred, it accompanied mate guarding. Four non‐mutually exclusive hypotheses to explain PE mounting were evaluated as follows: (1) gaining additional copulations, (2) prevention of re‐mating, (3) lengthening sperm residence time, and (4) re‐mounting as a function of female proceptivity. Male PE mounting did not aid males in gaining additional copulations nor did PE mounting prevent females from mating with new males. Equivocal support was found for Hypothesis 3: although there was much overlap in copulatory plug residence times for males who did and did not show PE mounting, one‐third of males who practiced PE mounting had plug residence times of 2 h or more, much longer than that of males who did not show PE mounting. PE mounting may therefore be related to increased plug residence time, which may provide an advantage to males in sperm competition. Strong evidence was found in support of Hypothesis 4: males overwhelmingly performed PE mounts in response to continued female sexual presentations, suggesting that females can solicit this male behavior. Females consequently exercise an even greater degree of control over males than was previously realized in this ‘female dominant’ primate.     

Relationship between male-male and male-female sexual behavior in 5-6-month-old male lambs

To characterize male–male sexual behavior during lamb development, to relate it with lamb body and testicular growth, and with sexual behavior toward estrual ewes, 40 Milchschaf male lambs, weaned at 45 days of age, were kept with ewes that were nursing younger lambs. Experimental lambs were weighed and scrotal circumference was measured every 2 weeks. Male–male sexual behavior was observed during 1–2 h every 2 weeks after birth until 7 months of age. Observations were recorded more intensively (3–4 h on five different days) for 2 weeks (5–6 months of age) as male–male sexual behavior increased during that period. Both mounting and mounted lambs were identified. An individual mounting index (MI) was calculated. To study male–female sexual behavior, lambs were individually located with two estrual ewes, and during 5 min the number of ano-genital sniffing, lateral approaches, mounts, and mounts with ejaculation were recorded. From those data, a libido index was also calculated. Male–male mounts (n = 308) were observed. Courtship behavior was displayed in 25% of interactions; mounts were accepted in 72.1% of attempted mounts. Mounts without previous courtship were accepted more frequently than mounts with previous courtship (P = 0.002). Lamb weight and scrotal circumference were not different according to MI groups. Lambs that mounted more times estrual ewes (first tertile) had greater (P = 0.04) MI (0.61 ± 0.10) than lambs with medium (0.27 ± 0.09) and less (0.30 ± 0.10) MI. The regression between MI and heterosexual libido index was r = 0.33 (P < 0.05). In summary, intensive male–male sexual activity during a short period of male lamb development was observed. There was a positive relationship between sexual behavior of male lambs towards other male lambs and towards estrual ewes.     

Techniques for the rapid preparation of permanent slides of microscopic algae

Because most techniques for the preparation of permanent mounts of algae have hitherto involved long alcoholic dehydration series, which frequently result in cell collapse if cut short, a method has been developed which is anhydrous from the start and avoids these series. It can be used to produce rapidly, permanent, generally-stained mounts of most microscopic algae in which the degree of shrinkage of the cell or its contents is reduced to a minimum.

A method for the cleaning and mounting of diatoms is also given.     

Preparation of Copolymers of Isobutyl Methacrylate and Styrene for Mounting Media

Details are given for the preparation of low molecular weight copolymers of isobutyl methacrylate and styrene for use in mounting microscopical sections between the slide and cover glass. Any refractive index in the range from 1.477 to 1.590 is available, depending upon the proportions of monomers used. A refractive index of 1.550 is recommended for general purposes, though other indices might be desirable in special cases including phase microscopy. The resin gives solutions in toluene of suitable fluidity at usable concentrations, adheres satisfactorily to glass, and has excellent light-transmission. The features which make it especially valuable are its optimum refractive index and its permanent water-whiteness.

Copolymers of isobutyl methacrylate and styrene may also be used to prepare plastic mounts of thick sections or gross specimens, which are optically cleared by the plastic mountant.     

Female-male mounting in Japanese macaques: the proximate role of sexual reward

Female Japanese macaques (Macaca fuscata), in certain populations, routinely engage in female-male mounting. In this study, we documented patterns of vulvar, perineal and anal (VPA) stimulation during female-male mounting in Japanese macaques. During approximately 45% of the female-male mounts analyzed, two thirds of female mounters engaged in VPA stimulation. Given the VPA region's primary role in mediating sexual response, the results of this research provide direct evidence bearing on the sexual nature of a substantial proportion of female-male mounts in Japanese macaques.     

Sexual performance of twin ram lambs and the effect of number and sex of contemporary siblings

The objectives of this investigation were to determine the degree of correspondence in the sexual performance of twin male sheep and to compare the sexual performance of ram lambs born co-twin to another male (M-M), co-twin to a female (M-F) and as single (S) offspring. Individual ram lambs (N=117), including 13 M-M twin sets, were exposed to four estrous ewes for 30 min at 7-day intervals over a 4-week period at 8 to 9 months of age.Frequencies of ejaculation (serving capacity) and mounts without ejaculation were recorded. M-M males averaged 2.9 ejaculations and 13.1 mounts per test. Individuals within 9 of the 13 M-M twin sets (69%) differed by an average of 0.5 or fewer ejaculations per test. Although variability within M-M twin sets was very low, variability between the 13 M-M twin sets was also low (coefficient of variation=10.6%). Consequently, frequencies of both ejaculation and mounting (without ejaculation) within the 13 twin sets were not correlated (P=0.50 and P=0.10, respectively). When the progeny of individual sires were compared, mounting frequencies were correlated (P<0.02) but not ejaculation rates (P=0.72). M-M, M-F and S ram lambs did not differ for either ejaculation frequency (P=0.26) or mounts without ejaculation (P=0.98). It was concluded that the sexual performance of related individuals is likely to be very similar and that the number and sex of contemporary siblings does not necessarily influence rates of mounting and ejaculation.     

Brilliant Cresyl Blue as a Stain for Plant Chromosomes

Methods are proposed for staining plant chromosomes with the dye brilliant cresyl blue, and for making these stained preparations permanent by using polyvinyl alcohol mounting medium.

The stain, which is composed of 2% brilliant cresyl blue in 45% aqueous acetic or propionic acid, is used with fixed material in making smear preparations. The technics for staining are similar to those employed in the aceto-carmine method.

The mounting medium is made by mixing 56% polyvinyl alcohol, which is diluted in water to the consistency of thick molasses, with 22% lactic acid and 22% phenol by volume. The permanent slides are made by floating off the cover slip of the temporary slide in 70% alcohol, then applying the mounting medium and replacing the cover slip.

The chief advantages of the methods described are:

1)The preparation of the stain is rapid and simple. The batch of stain will be good with the first try.

2)The staining procedure in some instances is shorter than when using aceto-carmine.

3)The stain shows a high degree of specificity for nuclear structures and gives better results than aceto-carmine when used on certain plant tissues.

4)A minimum number of cells is lost in making the slides permanent when using polyvinyl alcohol mounting medium as the slide and cover slip are run through only one solution prior to mounting.

5)The mounting medium dries rapidly and this shortens the time required before critical examination of the permanent mounts can be made.     

Bull-bull mounts in Holstein bulls: a survey of its incidence,possible causes,and consequences in Uruguayan bull’ breeders

Bulls frequently display male-male mounts, with consequences in the incidence of injuries, and possibly affecting the reproductive performance of the bulls. This behavior is known as the “buller syndrome” when appears in steers, with several individuals mounting one or a few penmates. The study aimed to collect information on the incidence of bull-bull mounts, the possible associated factors, the productive consequences, and management applied by distributing a survey to Holstein bull breeders in Uruguay. A survey was applied and responded by most Holstein breeders in Uruguay (30/33). Nineteen of the 30 breeders observed mounting behavior among bulls, and 15 of them considered it as a relevant problem. The breeders that observed the behavior had a greater number of bulls than those that did not observe it (P = 0.002). All of them observed that mounts were persistently directed towards the same individual (considering a specific period, while it remained in the group). Of these, 11 (58%) considered that this stopped only when the “buller” bull was removed from the group, mentioning that the behavior was frequently redirected to another individual. The mounts between bulls are a major problem in the breeding of Holstein bulls, with important consequences on weight gain and animal health, reproductive problems such as low libido and seminal quality, and even provoking the death of animals. Although not all breeders reported the existence of the problem, those with the bigger herds did. While some management and/or environmental conditions seem to influence (higher density, regrouping, managements that involve movement of animals, and spring) the incidence of bull-bull mounts, there are no standardized managements to avoid this behavior. Considering that most breeders were interested in including practices to minimize this problem if available, it would be essential to understand better the causes and predisposing factors to decrease its negative impacts.     

Copulatory Behavior as Courtship Communication

In the copulatory behavior of many species of rodents, mounting patterns with ejaculation are preceded by mounts with nonejaculatory intromissions. Although not directly related to insemination, these intromissions have generally been treated as “copulatory” behavior. If we treat these nonejaculatory intromissions as courtship communication in the tactile modality, new relationships become apparent. Within the context of classical ethology, intromissions can be considered in relation to both proximate dynamics and ultimate effects. Within the sociobiological/behavioral-ecological context, intromissions can be viewed in relation to manipulation, female assessment and choice, and honesty of communication. The intromissions synchronize, persuade, and orient at the same time as they manipulate the partner.     

The Venetian Turpentine Mounting Medium

As a mounting medium to follow aceto-carmine the following modification of Zirkle's is suggested: Venetian turpentine, 25 ml.; phenol, 50 ml.; propionic acid, 35 ml.; acetic acid, 10 ml.; water, 20 ml. The technic can be employed with either root-tip or pollen-mother smears, and has been used with quite a variety of plants. It is especially valuable where it is desired to make temporary mounts permanent. The method is simple, and with reasonable care no displacement of marked cells occurs.     

Modification of the Liquid Used in Spreading Polystyrene Embedded Sections

The new method of embedding histological specimens in polystyrene (Frangioni and Borgioli 1979) prescribes spreading and mounting the embedded sections on slides using a 10% paraldehyde solution on a hot plate set at 80 C; time required about 10 min. During this operation, analogous to that used for paraffin mounts (including the use of Mayer's albumen), sections rich in connective tissue or particularly hard often cannot be adequately spread due to the rapidity with which the paraldehyde solution evaporates. This disadvantage, which results in opacity where the mounted sections have not adhered to the slide, can be eliminated by modifying the solution as follows:     

Sociosexual behavior of captive sichuan golden monkeys (Rhinopithecus roxellana)

The Sichuan golden snub-nosed monkey, Rhinopithecus roxellana, is an endangered Colobine endemic to China. The social and reproductive behavior of this species are little known, and it has rarely been kept in captivity outside China. Results from observations of a captive golden monkey pair revealed some unusual details of sociosexual behavior. Both members of the pair mounted one other, and female mounting of the male occurred nearly as often as the reverse. Male mounts were always preceded by a stereotyped behavioral sequence that included distinct facial and vocal displays. Female mounts occurred in response to male solicitation (presenting). No evidence of ejaculation was observed in association with mounts, although mounts were only observed in a distinctly sexual context. Sexual behavior was associated with aggressive displays by one or both animals and with apparently proceptive behavior by the female. All sexual behaviors showed a peak near the end of the study, although the female was continually receptive throughout the 2-month study period.     

The “Dispersion Staining” Method for the Selective Coloration of Tissue

A method has been developed for the selective coloration of fixed tissue without the use of dyes. Microtome sections of formalin-fixed material are mounted under a cover glass in a mixture of two liquids such as diethylene glycol monobutyl ether with cin-namaldehyde and examined with the dark-field microscope. The refractive index of the liquid used for mounting must be of high dispersion and equal or close to the index of the specimen.

Tissue elements, dependent on their refractive index, whether slightly lower, the same as, or slightly above the mounting medium appear colored in shades of blue, red or yellow.

The optical principles involved in this optical dispersion method are similar to those involved in the production of colored light by the Christiansen filter.     

The “Dispersion Staining” Method for the Selective Coloration of Tissue

A method has been developed for the selective coloration of fixed tissue without the use of dyes. Microtome sections of formalin-fixed material are mounted under a cover glass in a mixture of two liquids such as diethylene glycol monobutyl ether with cin-namaldehyde and examined with the dark-field microscope. The refractive index of the liquid used for mounting must be of high dispersion and equal or close to the index of the specimen.

Tissue elements, dependent on their refractive index, whether slightly lower, the same as, or slightly above the mounting medium appear colored in shades of blue, red or yellow.

The optical principles involved in this optical dispersion method are similar to those involved in the production of colored light by the Christiansen filter.     

Mounting Interactions between Female Japanese Macaques: Testing the Influence of Dominance and Aggression

The goal of the work reported here was to determine whether female Japanese macaques (Macaca fuscata) participated in same-sex mounting interactions during homosexual consortships to communicate about asymmetries in their dominance relationships and to reduce aggression. Focal data were collected during 21 homosexual consortships involving 14 females living in a captive, mixed-sex group of 37 individuals. We identified eight types of mounts, one solicitation used specifically to request to mount (hands-on-hindquarters solicitation), two solicitations used specifically to request to be mounted (hindquarter and back presentations), and one behavior employed to facilitate mounts-in-progress (clasping). We tested whether dominant consort partners (1) mounted more and (2) requested to mount more than their subordinate partners and whether subordinate consort partners (1) requested to be mounted more and (2) facilitated mounts-in-progress more than their dominant partners. Finally, we examined whether mounting was temporally linked to the onset of aggressive interactions between consort partners and whether it functioned to defuse incipient aggression. None of these predictions was supported. All types of mounts, mount solicitations, and clasping occurred bi-directionally within consort dyads. Mutual sexual attraction and gratification provided the proximate motivation for these mounting interactions and, in turn, for the formation and maintenance of their homosexual consortships.