Fenestrated capillaries in the ventral sebaceous gland of the Djungarian hamster, Phodopus sungorus

The ventral sebaceous gland of the Djungarian hamster is a macroscopically visible organ situated in the midventral area of the abdominal wall. It consists of densely packed acini arranged in lobules with common excretory ducts. The rich vascular network of the gland is characterized by fenestrated capillaries. Fenestrated endothelium has not yet been reported as a characteristic and regular finding within sebaceous glands. Results are discussed with regard to proliferation rate of sebocytes and the demand of fluid and nutrient supply.     

Honeydew amino acids in relation to sugars and their role in the establishment of ant-attendance hierarchy in eight species of aphids feeding on tansy (Tanacetum vulgare)

Abstract. The ratio of the concentration of honeydew total amino acids to total sugars in the honeydew of eight species of aphids, all feeding on tansy, Tanacetum vulgare (L.), was determined and correlated with honeydew production and ant‐attendance. The honeydew of the five ant‐attended aphid species [Metopeurum fuscoviride (Stroyan), Trama troglodytes (v. Hayd), Aphis vandergooti (Börner), Brachycardus cardui (L.), Aphis fabae (Scopoli)] was rich in total amino acids, ranging from 12.9 to 20.8 nmol µL^?1 compared with the unattended aphid Macrosiphoniella tanacetaria (Kalt.) with only 3 nmol µL^?1. Asparagine, glutamine, glutamic acid and serine (all nonessential amino acids) were the predominant amino acids in the honeydew of all species. The total concentration of amino acids in the phloem sap of tansy was much higher (78.7 nmol µL^?1) then in the honeydew samples, and the predominant amino acids were glutamate (34.3%) and threonine (17.7%). A somewhat unexpected result was the finding that those aphid species with the highest total amino acid concentration in the honeydew always had the highest concentration of sugars. The lowest amino acid–sugar combined value was 104–28.8 nmol µL^?1 in the non ant‐attended species M. tanacetaria, and the highest value was an average of 270–89.9 nmol µL^?1 for the three most intensely attended aphid species M. fuscoviride, A. vandergooti and T. troglodytes. There is no evidence that any single amino acid or group of amino acids in the honeydew acted as an attractant for ant‐attendance in these eight aphid species. The richness of the honeydew (rate of secretion × total concentration of sugars), along with the presence of the attractant sugar melezitose, comprised the critical factors determining the extent of ant‐attendance of the aphids feeding on T. vulgare. The high total amino acid concentration in sugar‐rich honeydews can be explained by the high flow‐through of nutrients in aphids that are particularly well attended by ants.     

Multiple causes of pregnancy failure in hamsters precociously ovulated by human chorionic gonadotropin

Cycling adult female hamsters can be induced to mate and ovulate 24 h early by the injection of 20 IU human chorionic gonadotropin (hCG) at 1500 h on Day 3 (day before proestrus), but pregnancy is not established. Although there is evidence of decreased sperm transport in precociously ovulated females, this does not appear to be the primary cause of infertility. Reduced size and vascularity of corpora lutea (CL) in treated females suggests incomplete or failed CL activation. Control and hCG-treated females were killed by exsanguination under ether anesthesia at intervals for the first 5 days after mating. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol, and progesterone were measured by radioimmunoassay. Luteinizing hormone in treated animals was very high at 2200 h on Day 1 after mating (31 h after the hCG injection), due to endogenous release, and dropped below control levels thereafter. Follicle-stimulating hormone, by contrast, was significantly lower than controls at 2200 h on Day 1 and remained low until 2200 h on Day 3 after mating. Prolactin in treated animals was not different from that in controls, except for 1000 h on Day 4, when it showed a significant dip. Estradiol in treated animals was significantly higher than in controls at 2200 h on Day 1 (when LH was also high and FSH was low), and remained high at 1000 h and 2200 h on Day 2, dropping thereafter to control levels. Progesterone was initially at control levels but had dropped significantly by 1000 h on Day 2 and remained low for the next 24 h. These results suggest that pregnancy failure is due to inadequate activation of corpora lutea. This may be due to: 1) immaturity of follicles at the time of ovulation; 2) inappropriate timing of preovulatory events; 3) the luteolytic effects of high levels of LH or estradiol or both; 4) the low level of FSH in the early stages of corpus luteum development; or 5) a combination of the above. Abnormalities of prolactin secretion were not investigated in detail but cannot be ruled out at this time.     

Blockade of a motor response by cholinergic stimulation of the toad midbrain tegmentum

Application of an acid solution to the dorsal skin of conscious toads having intact nervous system induces a scratching reflex and escape movements, as well as autonomic alterations (hypertension and tachycardia) that are part of the defense response. The motor components of this response are abolished or reduced by microinjection of 60, 30, 15 or 7.5 ng carbachol into the midbrain tegmentum. The cardiovascular components, however, continue to be present, although their amplitude is reduced. The depression of the motor response is statistically significant up to 15 minutes for the 60 ng dose, up to 10 minutes for the 15 and 30 ng doses, and only up to 5 minutes for the 7.5 ng dose. The data suggest that the midbrain tegmentum may modulate the reflex motor response triggered by a noxious stimulus and also participate in the organization of the escape movements. The importance of cholinergic agents in this modulation is discussed. The persistence of the cardiovascular component of the response shows the importance of this parameter as an indicator of alert situations.     

An automated device for the preparation of complex reagent mixtures. The immunofluorescence tomograph

A microcomputer-controlled device was built that automatically prepares small volumes of mixtures of up to eight reagents. The operation of the system is fast, flexible, and reliable, thus making possible the routine use of experimental protocols that require large numbers of small volume reagent samples, each having a different composition. In particular, the software we developed for this device handles the preparation of three-antibody staining solutions to be used in triple labeling immunofluorescent flow cytometry experiments that involve only two fluorochromes. In this role, the device is known as an "Immunofluorescence Tomograph."     

Hematologic and immunologic responses in common marmosets (Callithrix jacchus) infected with Plasmodium knowlesi and Epstein-Barr virus

The hematologic and immunologic responses to infection with either the Epstein-Barr virus alone or infection with Epstein-Barr virus and Plasmodium knowlesi were studied using common marmosets (Callithrix jacchus). The assays performed included complete blood cell counts, determinations of natural killer cell activity, and determinations of antibody titers to Epstein-Barr virus early antigen, virus capsid antigen and the nuclear antigen. While no animal showed signs of lymphoproliferative disease, it was found that animals infected with Epstein-Barr virus became positive for early antigen, virus capsid antigen and nuclear antigen at low levels. No difference in antibody titers between Epstein-Barr virus infected animals and co-infected animals was observed. An increase also was found in the number of leukocytes in all groups, and an increase in natural killer cells following infection with Epstein-Barr virus. Some depression in natural killer cells was observed in the co-infected animals when compared to Epstein-Barr virus infected animals.