SD Strain Research Articles

摘出ラット胸部大動脈の血管機能に対する高コレステロール血症の影響

Mature male rats (SD strain, 8-week-old) were fed with a normal diet or a high cholesterol diet (HC: 1.5% cholesterol and 0.5% Na cholate in the normal diet) up to 8 weeks, and we examined how the vascular function level of the isolated thoracic aorta and the histological figures of some tissues including the aorta would change. 1) The contracting reactivity to phenylephrine (Phe, 10 microM) and the relaxing reactivity to acetylcholine (1 microM) measured thereafter remained unchanged during the period of aging and were not influenced by HC-feeding. The addition of L-arginine (Arg, 100 microM) did not affect the results. 2) The ability of the aorta to release NO and to relax, which was evaluated as the extent of the endothelium-dependent potentiation by NG-monomethyl-L-arginine (NMA) of the Phe contraction, did not change by HC-feeding up to 4 weeks, but appears to be attenuated after 8-week feeding. 3) The EC50 of NMA for the potentiation estimated without the addition of Arg remained unchanged, while the one in the presence of Arg gradually increased with aging but not with HC-feeding. 4) The histopathological study of the aorta and other tissues failed to detect any notable atherogenic changes in any of the HC-fed groups. The results indicate that under the experimental conditions employed, HC-feeding would not develop any significant atherogenic histopathological changes in the endothelium-smooth muscle preparation, but may induce some dysfunction in the NO-release mediated and auto-regulatory function of the vascular tone.

樹脂鋳型法によるラット皮膚血管構築の観察

The angioarchitecture of the skin in the SD strain rat was investigated by scanning electron microscopy using resin cast. The neck part of rat skin was composed of 3 layers of vascular networks: the first layer (superficial layer), the second layer (middle layer), and the third layer (deep layer). Two types of capillary architectures were present around the hair follicle: small architectures composed of random network and large architectures composed of 3 parts distinguished by the construction of network. The large architecture, the capillary of hair papilla and the capillary network of sebaceous gland was thought to compose one circulation unit. The afferent vessels into such units branched from Kandelaberarterie-Petersen occurring from the 3rd layer, ascended to the 2nd layer, then descended to the bottom of the network and composed the capillary architecture. There were 2 types of efferent vessels from such circulation unit. They occurred from superficial and deep part, respectively, of the vascular architecture around the hair follicle and descended straight to the 3rd layer. The presence of straight vessels between the 2 nd and 3 rd layer, and the simple arrangement of vascular layers were thought to be characteristic of the angioarchitecture of the rat skin.

Effect of trans-4-hydroxy-3-methoxycinnamic acid (ferulic acid) on polyamine level in the rat ventral prostate

Ferulic acid (FA) specifically inhibits the growth of the ventral prostate in rats not through antiandrogenic mechanisms (Saito et al. Experientia 35: 696, 1979). Levels of polyamines in the rat ventral prostate were determined before and after FA administration (10, 25 and 50 mg/kg BW, s.c., for 5 days). SD strain male rats, 5 approximately 7 weeks of age, were used. The ventral prostates were homogenized with 10% TCA and centrifuged. The supernatant was washed twice with diethylether, freeze-dried, and redissolved in distilled water. Then, the contents of putrescine, spermidine and spermine were measured by an isotachograph (LKB), using a leading buffer composed of 5 mM Ba(OH)2/15 mM valine, pH 9.94, and a terminating buffer composed of 20 mM triethylenediamine, pH 10.20. Total polyamines were reduced dose-dependently (12.12, 9.95, 9.10 and 7.74 nmol/mg wet tissue at 0, 10, 25 and 50 mg/kg FA, respectively). Spermidine was more sensitive to FA than spermine. According to the attitude of the Spermidine/Spermine ratio, the inhibition of ornithine decarboxylase by FA has been suggested.

Effects of Molybdenum and Tungsten on Mammary Carcinogenesis in SD Rats23

Virgin female rats of the SD strain were fed ad libitum a nutritionally adequate semipurified diet and demineralized water (groups 1 and 2), or the same diet with 10 ppm molybdenum (group 3) or 150 ppm tungsten (group 4) added to the drinking water. The animals in groups 2-4 received a single iv injection of 5 mg N-nitroso-N-methylurea (NMU; CAS: 684-93-5)/100 g body weight at 50 days of age. One hundred and twenty-five days after the NMU treatment, group 2 exhibited a 50.0% incidence of mammary carcinoma. Group 4 exhibited a significant increase in carcinoma incidence (79.2%) and the value for group 3 (45.5%) was not significantly different from that of group 2. The carcinoma incidence of group 3 (50.0%) was significantly lower than that of group 2 (90.5%) or group 4 (95.7%) 198 days after NMU treatment.

口こう外科領域におけるアスポキシシリン（ＡＳＰＣ，ＴＡ‐０５８）の基礎的検討

Experimental study on Aspoxicillin (ASPC, TA-058), a new parenteral penicillin was carried out and the folloing results were obtained:In vitro antibiotic activity of ASPC against 47 clinical isolates from oral infection cases were examined. The peak of the minimum inhibitory concentration was 0.39 μ g/ml and 80% inhibitory concentration was 1. 56 μ g/ml.Using SD strain rats, distribution of ASPC, ABPC and PIPC after intravenous administration in plasma and in oral tissues such as the gingiva, mandible, alveolus, submaxillary gland, tongue and masseta were assayed. Concentration after administration of ASPC in plasma and oral tissues was similar to that ABPC and superior to that of PIPC.These results suggested usefulness of Aspoxillin in the treatment of infections in the field of oral surgery.

Plasma alkaline phosphatase (ALP) in IS rats and its possible origin.

The activities of alkaline phosphatase (ALP) from plasma at several ages were determined, and the origin of plasma ALP was investigated on the basis of the electrophoretic migration and the optimum pH in IS strain of rats (IS rats) and SD strain of rats (SD rats). Both in IS and SD rats, the activity was highest at the youngest group (8 weeks), and it decreased rapidly with age. The activities in IS rats at 8 and 10 weeks of age were 63% and 66% of those in SD rats. At 20 and 30 weeks of age, the difference was not clear. The zymogram gave two bands for SD rat plasma. One of the bands was regarded as the intestinal isozyme and the other was the osseous and/or the hepatic isozymes. The zymograms of IS rat plasma gave only one band which fairly consistent with that of the osseous or hepatic isozyme, and no intestinal isozyme was detected. The mobility of the intestinal isozyme was not completely identical between IS and SD rats. Thus, the molecular difference in the intestinal isozyme was thought to be a cause of the difference in the ALP activity and isozyme composition of the plasma between these two strains. The zymograms for other tissues did not show any difference between IS and SD rats. The effect of the change in pH on ALP activity also suggested that the plasma ALP in IS rats did not contain any intestinal isozyme.

発育期の運動処方に関する実験的研究

To get basic data on exercise prescription in the growing stages, it was attempted to investigate the growth of white albino rats (JCL : SD strain) under the various swimming loads. Following results were obtained.A. The effects of exercise prescription to small cage raising:1) Non-swimming small cage (7.5×15×20cm) group was resulted -17.5% accumulated food intake, -14.3% average body weight and -6.8% average tail length to the non-swimming normal cage (15×30×20cm) group.2) In 16 min and 96 min actual swimming time/week, small cage groups were little or no diminished on the difference of the body weight and tail length to each corresponded normal cage groups.B. The amount of swimming time and the peak value of growth:1) In 48 min actual swimming/week, peak values were observed on the femur length, gastrocnemius and femur weight.2) In 96 min actual swimming/week, peak values were taken on the tail length, body, heart and adrenal weight.3) In 384 min actual swimming/week, no peak value was observed, and significant decreases were indicated on the femur length, gastrocnemius and femur weight to the non-swimming.C. The growing difference between intermittent and continuous swimming:1) In 16 min and 96 min actual swimming/week, continuous (repetitions 16 min swimming and 2 min rest) groups were obviously higher than in intermittent (repetitions 2 min swimming and 2 min rest) groups on the food intake, tail and femur length, heart, adrenal, liver, kidney, gastrocnemius and femur weight, cross section area and marrow cavity area of femur, except the body and spleen weight.2) In 384 min actual swimming/week, however, continuous group was indicated such remarkable decrease on almost all tissues and organs that the body, spleen and gastrocnemius weight were showed lower than the non-swimming group.D. The tendency of growing process about training frequency and actual swimming time:1) It was found that the larger grow in training frequency (1 day, 3 days and 6 days/week) and actual swimming time (60 min and 120 min/week), the more increase in the food intake, heart weight, adrenal weight, breaking bending load, proportion of muscle fiber and average area/fiber in cross section of gastrocnemius.2) But, on 3 days training frequency in 60 min actual swimming and 1 day training frequency in 120 min actual swimming, the tail and femur length, and gastrocnemius and femur weight were the largest growth among these three training frequency.3) The bending strength of femur on 3 days training frequency was indicated the strongest one in both of 60 min and 120 min actual swimming groups.

Leucocyte migration and complement activation in rat carrageenin induced pleurisy.

Pleurisy was induced by intrapleural injection of 0.1ml of 2% λ-carrageenin in male rats(SD strain, SPF, 8-9weeks). Complement titers were measured by Lachmann’s method(50% hemolysis, CH50), using EAC142, which was made by preincubation of erythrocytes with zymosan-treated serum. Complement titers in pleural exudate, expressed in terms of mg protein, were lower than those in serum during the whole course. Considering the in vitro complement activation of rat serum with carrageenin, it could be concluded that complement was activated in pleural cavity. Pleural exudate accumulation began rapidly 1-3 hr after carrageenin injection. Polymorphonuclear leucocytes (PMN) increased their numbers rapidly up to 5 hr and stayed at the same level thereafter, whereas mononuclear leucocyte (Mono) numbers increased gradually up to 24 hr. Using dexamethasone(arachidonic acid(AA) release inhibitor), benoxapro-fen(a lipoxygenase inhibitor with a weak cyclooxygenase inhibition) and K-76COONa(an inhibitor of complement activation), it could be concluded that PMN migration was induced by arachidonic acid metabolites and activated complements. Mono migration particularly in the late phase might be induced by lipoxygenase products.

PAS positive proteins found in functional segments of the submandibular gland cells in rats treated with mercuric chloride or cadmium chloride

The experiment was carried out to observe effects of HgCl2 or CdCl2 on elec-trophoretic patterns of PAS positive proteins in dissociated functional segments and cell fractions of rat submandibular gland. Four groups of adult SD strain male rats were injected with 2mg Hg/Kg of HgCl2 or 2mg Cd /Kg of CdCl2 subcutaneously and sacrificed three days or seven days after. The submandibular gland was then dissected out and freed from soft tissues; and thereafter, samples for SDS-PAGE were prepared in two ways :1. The gland units were dissociated by sequential collagenase digestion and microdissection with a needle and divided into acinus(I), convoluted duct with intercalated tubule (II), Striated duct (III) and excretory duct (IV), and most parts of each segment were collected into a capillary. 2. The gland was homogenized in 0.25M sucrose solution and fractionized into total homogenate(1), 1.000Xg pellet(2), 10.000Xg sup.(3) and 10.000Xg pellet(4) by centrifugation. Each sample was dissolved with SDS solution and electrophoresed on 4-40% gradient micro-PAG. The gel was stained with Schiffs reagent, and electro-phoretic profile of PAS positive proteins was traced with a microdensitome-ter. The results show that effects of Cd or Hg on the PAS positive proteins in submandibular gland cells were observed only in the acinus; and in the case of Cd adm.,one band at the original site stained more intensely as compared with the control. On the other hand, in the case of Hg adm., a band with the highest mobility at the front site showed decreasing tendency in PAS staining. Similar profiles were also observed in the l,000Xg pellet and 10,000Xg supernatant for Cd adm. and the 1,000Xg pellet for Hg adm..

Low-molecular-weight, chromium-binding substance in rat lungs and its possible role in chromium movement.

Male SD strain rats were subjected to 5 hr inhalation exposure to CrCl3. 6 H2O aerosol (13.3 mg Cr/m3, particle size<2 μm), killed at intervals of 1, 2 and 7 days after exposure and Cr contents in the total organ, high-molecular-weight fraction (Cr-HMW) and low-molecular-weight, Cr-binding substance (LMCr) were determined in the lungs and liver. Total Cr contents in the lungs stayed at a level approximately 8 to 25 times higher than those in the liver. Sephadex gel filtration revealed that only 3 to 10% of the total Cr was retained in LMCr in the lungs in contrast to 56 to 71% in the liver. The percentages of Cr-HMW in the total lung and liver Cr were 60 to 70% and 15 to 25%, respectively. Cr-HMW and total Cr contents in the lungs showed a slow and comparable decrease after exposure. In contrast, LMCr in the lungs gradually increased in parallel with LMCr in the liver, showing levels approximately equal to the latter. A statistically significant correlation was observed only between LMCr in the lungs and each of Cr-HMW, LMCr and total Cr contents in the liver. A linear one-compartment kinetic model gave estimates of the biological half-times of 12.8 days for lung Cr and 1.2 days for liver Cr. These results suggest that LMCr in the lungs is in equilibrium with Cr in the rest of the body and participates in the movement of Cr from the lungs to other organs. The long half-time possibly resulting in the accumulation of Cr in the lungs may be explained by the slow rate of LMCr synthesis in the lungs.

Anti-IgE and Con A-induced histamine release from mast cells of four rat strains: correlation with total serum IgE.

Anti-IgE- and Con A-induced histamine release from serosal mast cells were compared to each other and to total serum levels of IgE in non-immunized, alum-injected, and Silica gel-injected rats of the BN, Fischer, PVG, and SD strains. The results indicate that the degree of anti-IgE- and Con A-induced release is strain-dependent and varies with immunization conditions. Furthermore, there is a gross but not complete correlation between the degree of serosal mast cell histamine release induced by the two secretagogues. However, Con A- or anti-IgE-induced release could significantly be correlated to serum levels of total IgE only in the Fischer strain but not in the BN or the PVG strains. In the SD strain, Con A-induced release correlated to serum IgE levels in Silica gel-injected but not in alum-injected animals.

Susceptibility of Mammalian Hosts to Larvae of Gnathostoma doloresi Tubangui 1925

Gnathostoma doloresi is widely distributed in the South Pacific and Southeast Asia. The adult worm lives in tumors in the wall of the stomach and is commonly found in wild boars or rarely in pigs in the middle and southern areas of Kyushu, Japan. Miyazaki and Ishii (1952, Acta Med. 22: 467-473) and Ishii (1956, Fukuoka Acta Med. 47: 1474-1494) first discovered advanced third stage larvae encapsulated in two species of salamanders, the second intermediate hosts. The same larvae were found in snakes on Ishigaki Island, Okinawa, by Miyazaki and Kawashima (1962, Kyushu J. Med. Sci. 13: 165-169) and on Amami-Oshima Island, Kagoshima, Japan, by Tada et al. (1969, Jpn. J. Parasitol. 18: 280293). The infectivity and the migratory behavior of the larvae of G. doloresi in humans have not been established, thus a monkey and other mammals were experimentally infected with the larvae. In our experiments the larvae used for infection were isolated from snakes (Trimeresurus flavoviridis flavoviridis) captured on Amami-Oshima Island. The muscles of 20 snakes were minced, examined with a dissecting microscope and a total of 182 encapsulated larvae were recovered. These larvae were removed from the capsules in order to identify them as G. doloresi. One monkey (Macaca mulatta), one dog and one cat were each fed 20 infective larvae. The animals were necropsied 90 days postinfection and the gastric walls, intestines, livers, kidneys, lungs, hearts, and muscles were inspected for larvae. Two guinea pigs, three rats (SD strain), and two fowl were fed 10 larvae each, killed after 60 days and examined in the same manner. Five and eight larvae were recovered from the muscles of one monkey and one dog, respectively. They had increased in size, ranging from 3.2 x 0.36 to 5.7 x 0.51 mm in the monkey and from 3.6 x 0.43 to 4.8 x 0.46 mm in the dog, as compared with their size prior to inoculation which was 2.1 x 0.27 to 2.9 x 0.30 mm. Four larvae (2.8-3.6 x 0.370.40 mm in size) were from the muscles of one rat and six (2.8-3.5 x 0.38-0.52 mm in size) from two guinea pigs. None were detected in the tissues of one cat, two of three rats or the two fowl. In the rodents sacrificed at 60 days, most larvae were encapsulated in the muscles, whereas the larvae found in the monkey and the dog remained mostly free in the tissues at 90 days postinfection. The larvae recovered showed no morphological alteration but their body color had changed to bright, bloody red. This tint was much deeper in the free larvae, and such may have been caused by the accumulation of oxyhemoglobin in the body fluid following ingestion of red blood cells. These findings suggest that the larvae may move intermittently in the tissues and may be able to invade various other organs, as is the case with Gnathostoma spinigerum. Blood samples were collected at weekly intervals from the monkey, to prepare coverslip smear preparations for differential counts of leukocytes and to determine erythrocyte and leukocyte counts. In addition, the activities of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase and the albumin-globulin ratio were estimated in the serum until the animal was killed 90 days postinfection. Leukocyte counts were elevated up to 11.4 x 103/ mm3 during the 3rd wk and the increases were moderate during the 10th wk. Such a pattern of marked leukocytosis was caused primarily by an increase in the number of eosinophils (5 x 103/mm3). There were no significant changes in RBC counts. The blood chemistry examinations done to detect possible disorders of hepatic function if and when the larvae

The behavior of 7, 12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats during pregnancy and lactation and hormone levels in the pituitary and plasma (author's transl)

In order to keep a long-term lactation in primiparous SD strain rats with DMBA-induced mammary tumors, 5 pups aged 5 to 10 days were exchanged every 10 days. FSH, LH and prolactin (PRL) in pituitary tissues and FSH, LH, PRL, estradiol (E2) and progesterone (PRG) in plasma were determined during pregnancy (1,2 and 3-week), at paturition (0 to 12 hours after parturition) and during lactation (1,2,3,4,5 and 6-week). Experimental rats were divided into 6 groups according to the lactating period (non-lactating 3,6,8,12 and 17-week). Blood samples were collected by cardiac puncture 1 hour after an intraperitoneal injection of urethane (150 mg/100 g body weight), and the pituitary gland was removed simultaneously. During pregnancy, plasma PRL was low in the first and second week. PRL, E2 and PRG were high in the third week, during which DMBA-induced mammary tumors began to proliferate. PRG in plasma in the third week was lower than that of the second week. After paturition, the tumors regressed and did not develop for three weeks of lactation, during which plasma PRL was high whereas E2 and PRG were low. The tumors began to proliferate again from the fifth week of lactation, during which E2 was high and the estrous cycle reappeared. The behavior of DMBA-induced mammary tumors in rats during pregnancy and lactation seems to be closely related to plasma estrogen levels.

Strain differences in the response to morphine on incorporation of 3H-lysine into rat brain protein.

The effect of morphine on the specific activity (SA) of lysine in the plasma free amino acid (FAA) fraction and in the cerebral cortical FAA and protein fractions, as well as on the specific accumulation and incorporation, was determined in male Sprague-Dawley and Wistar rats at various time intervals after intravenous injection of drug and amino acid into unanesthetized animals. The lysine SA was higher in Sprague-Dawley than in Wistar rats in the plasma and brain FAA fraction and in the protein fraction. In the SD strain, morphine decreased the SA of plasma FAA significantly, but had only slight effects in the Wistar strain. In the cortical gray matter, morphine elevated the SA of lysine significantly in both strains, although the rate of decrease of SA with increasing time after injection was different in the two strains. SA of the lysine in cerebral cortical protein increased in both strains with time, but did so more rapidly in the Sprague-Dawley strain. When the data for the free amino acids were expressed in terms of specific accumulation, the observed rates were higher in the Sprague-Dawley animals and reached a point of maximal concentration, which was not observed in animals of the Wistar strain. Morphine elevated the levels of specific accumulation of lysine into the cortical free amino acid pool in both strains of rat. However, specific incorporation of lysine into the cerebral gray cortical protein in control animlas was essentially similar in both strains. Despite the similarity in specific incorporation of lysine into brain protein in both strains of control rat, morphine treatment caused a much more marked inhibition of incorporation of lysine in the Wistar rats. Thus, it is concluded that Sprague-Dawley and Wistar rats are not equivalent in relation to the accumulation of an amino acid in the brain FAA pool from the plasma and that the effect of morphine on specific incorporation of lysine into brain protein is greater in Wistar rats.

無菌ラットおよび普通飼育ラットの辺縁歯肉に対する持続的圧迫刺激の影響に関する研究

The changes of the periodontal tissues irritated mechanically by small active elastic rings on the survival portion of the right first molar were observed microscopically in germfree and conventional JCL: SD strain rats.The results obtained were as follows:1. Pocket formation, slight infiltration of inflammatory cells into the periodontal tissues and hyaline degeneration or disappearance of the gingival fibers in some degree were noticed in germfree rats.2. More sever inflammatory changes of the periodontal tissues such as epithelial acanthosis, ulceration, disappearance of the gingival fibers, wide spread inflammatory cell infiltration, alveolar bone destruction and abscess formation in the bifurcation of the teeth in conventional rats were distinctly recognized than in the germfree rats.3. The depth of the pockets in conventional rats was 0.8mm to 0.9mm and about twice of the depth in germfree rats.

Long term surveys on Tyzzer's disease in three rat breeder colonies (author's transl)

Retired rats of SD strain from three breeder colonies (A, B and C) were monthly monitored for CF antibody to Tyzzer's organism for 2 to 6 years. In colony A, antibody-positive rats were found at frequencies ranging from 5 tp 100% with a single peak during about one year without any detectable signs of apparent disease. However, in colony B, in spite of the outbreak of the disease, antibody-positive animals were only sporadically detected during about 4 years after the outbreak. Thereafter, in this colony, the antibody was not demonstrated in all animals examined for 2 years, and susceptibility to the disease of 3-week-old rats was the same as that of ones from one-infected colony. Cortisone test did not suggest the infection. In colony C, no antibody-positive rats were detected for 3 years.

In vitro and in vivo evaluation of ceftezole, a new cephalosporin derivative.

Ceftezole, a new cephalosporin derivative, was compared with cefazolin, cephaloridine, and cephalothin. Data obtained indicate that it is a broad-spectrum antibiotic, with almost identical antimicrobial activity against pathogenic organisms isolated from patients. The therapeutic effect of ceftezole on experimental infections in mice was similar to that of cefazolin and was superior to that of cephalothin. The binding of ceftezole to serum proteins was somewhat less than that of cefazolin. The concentrations of ceftezole in the sera of test animals and human volunteers were determined after intramuscular injection of 20 mg/kg and after a single dose of 500 mg, respectively. The concentration of ceftezole in the serum of volunteers peaked at 24.9 mug/ml 15 min after injection and remained effective (about 2.6 mug/ml) at 4 h. The half-life in serum under the same conditions was 56 min, i.e., about one-half that of cefazolin. The 24-h urinary recovery rate was 87.5%. Most of the administered ceftezole was excreted unchanged mainly through the urinary tract. The biliary excretion rate in SD strain rats after intramuscular injection of 20 mg/kg was about 4.4%. As compared with commercially available cephalosporins, ceftezole was second only to cefazolin in biliary excretion rate. Various tissue levels of ceftezole in animals were higher than cephalothin but, with the exception of renal levels in the early stage after administration, were lower than cefazolin.

Two Independent Inversions in the X-chromosome of &lt;i&gt;Drosophila virilis&lt;/i&gt; and Their Effects on Crossing Over and Disjunction

1. A strain of D. virilis, having two independent inversions in the X-chromosome In (X) Spd, were obtained by X-ray treatment. The extents of the inversions are illustrated in Figs. 1, 2. From this original strain two secondary strains In (X) Sp and In (X) Sd, each with one of these inversions, have been derived through the crossing over in the intercalary section.2. All the In(X) Spd, In (X) Sd and In (X) Sp strains greatly ;suppress the crossing over in the regions included in the inversions. That of the intercalary section in In (X.) Spd is also suppressed to no smaller degree. The crossing over in the uninverted distal sections in all the three strains is suppressed very little, except possibly that in the directly adjacent regions, The crossing over in the section proximal to In (X) Sd is suppressed more markedly.3. The heterozygous In (X) Spd strain throws 13-14 times as many primary exceptions of either sex as the normal strain, the sex-ratio among the exceptions being 1 _??_:5.4 _??_ The In (X) Sd strain throws nearly half as many primary exceptions as does the In (X) Spd strain. The In (X) Sp strain does not produce any greater number of exceptions than the normal strain.4. The secondary non-disjunctions are 10 times as frequent in the heterozygous In (X) Spd strain as in the normal strain, the sexratio among the exceptions being 1 _??_:1.24 _??_ Some superfemales and some XO males were found among the progeny of the XXY females.5. The reduction of crossing over by the heterozygous inversion is apparently due to various causes. The fact that the breakage points of an inversion have a common property with the centromere, in that the pairing chromosomes remain in asynapsis in their proximities, is to be counted among them.6. The primary non-disjunction is correlated somehow with the suppression of crossing over especially in the middle region of the chromosome, where chiasmata are most concentrated.7. The suppression of chiasmata plays a more important role for the secondary non-disjunction than for the primary non-disjunction. The comparative scarcity of secondary exceptions and the marked disparity of sexes among them in D. virilis, seem to be correlated with the more intimate regional affinity of the X-chromosomes in this species than in D. melanogaster.