j. perinat. Med. The effect of maternal smoke exposure on

Kaufmann et al, Maternal smoke exposure and fetal blood vessels 309

j. perinat. Med. The effect of maternal smoke exposure on the infrastructure of fetalH (1986) 309 peripheral blood vessels in the mouse

Robert C. Kaufmann, Kofi S. Amankwah, and Aruna D. Weberg

Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecolo-gy, Southern Illinois University School of Medicine, Springfield, Illinois,U.S.A.

1 Introduction

The harmful effect of maternal cigarette smok-ing on the fetus is variable and may result in"only" a decrease in weight or may cause deathby abruptio placenta [10]. In adults, smokingcauses pathological changes in the cardiovascu-lar system [9]. Some authors have proposedthat smoking during pregnancy may also causepathological changes in the cardiovascular sys-tem of the fetus that would increase the risk ofheart and peripheral vascular disease in adult-hood [2, 4]. The placenta and umbilical cordvessels of human fetuses whose motherssmoked during pregnancy have been found tocontain ultrastructural changes [1—5], Thesechanges were seen in the fetal vessels that areclosest to the point of noxious transfer. Thisstudy was done to determine if similar ultra-structural changes could be seen in fetal periph-eral vessels far removed from the point ofnoxious transfer. Because of the relative un-availability of human fetal tissue for ultrastruc-tural study, an animal model of smoking duringpregnancy was chosen to carry out this project.

2 Materials and methods

All mice in this study were of the C57BL/KsJ—hm/+m strain obtained from JacksonLaboratory, Bar Harbor, Maine. Female and

Curriculum vitae

ROBERT C. KAUFMANN,M.D., born 1951, U.S.A.,graduated 1973 B. S. 1976M.D.,from Southern Illi-nois University School ofMedicine, Springfield, Illi-nois. Certified AmericanBoard of Obstetrics andGynecology. Licensurewith State of Illinois. Fel-low, American College ofObstetricians and Gyneco-logists. Member of American Medical Association, Socie-ty of Perinatal Obstetricians, Illinois State Medical Socie-ty, Central Perinatal Association of Illinois, and SouthCentral Illinois Perinatal Consortium. Faculty membersince 1980, Assistant Professor, Division of MaternallFetal Medicine, Department of Obstetrics and Gynecolo-gy, Southern Illinois University School of Medicine,Springfield, Illinois since 1982.

male, two to three month old mice were placedin a breeding cage and exposed to cigarettesmoke by placing their cage in a special smok-ing chamber (figure 1) similar to that used byYOUNOSZAI [12]. This specific device was chosenbecause it employs a regimen of intermittentsmoke exposure over a lengthy period of timesimulating the effects of smoke in a confinedspace much like that found in many workingenvironments. Low tar cigarette smoke was

1986 by Walter de Gruyter & Co. Berlin · New York

310 Kaufmann et al, Maternal smoke exposure and fetal blood vessels

• r

Figure 1. Smoking chamber containing a cage of preg-nant mice. The chamber top was covered with aplexiglass lid. A separatory funnel on the side of thebox served as a smoking device, holding a cigarette in

place by means of one-holed stop cock. The other endof the funnel was attached to a tube ending in a rubberbulb which was used to force the cigarette smoke intothe chamber.

blown into the chamber for four minutes, fivetimes daily, except on weekends when it wasdone three times a day. This method has beenshown to produce a carboxyhemoglobin levelof approximately 9.0% which is similar to thatfound in an adult human smoking one pack ofcigarettes per day.When not being exposed to smoke, the micewere housed in a room with 12 hour light/darkcycle. Similarly caged mice of the same strainwere used as control animals, placed in a cham-ber but not exposed to smoke, and housedin the same room. Both groups of mice hadlaboratory chow and tap water ad lib for 24hours/day. The amount of food ingested byboth groups was weighed daily. The mice be-came pregnant and delivered in the same cage.After spontaneous delivery the live pups wereweighed. Two pups from the litters of threedams in both the control and study groups weretaken for this study, yielding a total of six pupsin each group. The remaining pups were usedfor other studies. Each pup was sacrificed vianeck fracture, and the entire pup was immersedin a solution of 2.5% gluteraldehyde in 0.1 Mcacodylate buffer at pH 7.3. While still undersolution, the rear leg muscles were dissectedfree, sliced, and immersed in the same preserv-ative for four to five hours. They were thenplaced in fresh 2.5% gluteraldehyde mixtureovernight. The tissues were postfixed in osmium

ferrocyanide and en-block stained with uranylacetate in a graded series of alcohol. The tissueswere infiltrated with and embedded in Spurr.Sections were taken via an ultramicrotome andpost stained with uranyl acetate and lead cit-rate. Six to eight sections from each animalwere examined in a Phillips 201 electron micro-scope at 60 KV, with the examiner being blindedas to which sections were from control orsmoke-exposed animals.

3 Results

3.1 Perinatal findings

Carboxyhemoglobin levels were performed onthe eighteenth day of gestation in two pregnantsmoke-exposed mice, and both yielded a valueof 9.0%. These levels were drawn after twoepisodes of smoke exposure on that day andjust before the third episode. The amount offeed ingested per animal during the gestationalperiod did not differ between the. two groups.Litter size was not significantly different be-tween the smoke-exposed and control animals,5.09 and 4.73 respectively. There were a totalof 61 pups born in 14 litters in the smoke-exposed group and a total of 57 pups born in12 litters in the control group. The mean birthweight was slightly but significantly smaller inthe 16 smoke-exposed pups that were weighed

J. Perinat. Med. 14 (1986)


(1.3014 ± 0.0552 gm) vs. the 54 control pups(1.3620 + 0.1141) (p < 0.05). The smoke-exposed pups tended to be killed soon afterbirth by the older mice in the cage. Newbornpups that were present and alive in the smokingcage would be killed soon after the onset ofexposing them to smoke. Pups that were bornduring a smoking period were killed almostimmediately. However instead of being eatenafter being killed as is usually the case withdead mouse pups, they were just left. This factalong with the use of some of the smoke-ex-posed pups for other studies accounted for thesmaller number of pups being weighed in thesmoke-exposed group as compared to the con-trol group.

3.1 Ultrastructural findings

Control group: In the peripheral blood vesselsin these fetuses, the endothelial surface wasrelatively smooth, containing only the usualsmall pinocytotic vacuoles, normal length mar-ginal folds, and occasional fingerlike protru-sions of the cytoplasm into the vascular lumen(figures 2—4). The mitochondria and endo-

Figure 3. A capillary from a normal fetus with smoothluminal borders and normal thin cytoplasm. An endot-helial nucleus (Nu) and mitochondria (M) are visible.MAG 10,572.

Figure 2. An arteriole from a control fetus with relativelysmooth luminal surface of the endothelial cell (E). Redblood cells (RBC) and two pericytes (P) are visible.MAG 7194.

Figure 4. A small vessel from a control fetus with asmooth endothelial luminal border containing pinocyto-toc vessels (V) and a fingerlike cytoplasmic protrusioninto the vascular lumen (F). MAG 10,572.



plasmic reticulum were histologically normal(figures 2 and 4).Smoke-exposed group: The blood vessels fromfetuses whose mothers were exposed to smokewere markedly abnormal. The most strikingfinding was the appearance of endothelial vacu-oles located in the substance of the cytoplasm(figures 5 — 7). These blister-like vesicles havebeen termed vacuole-type endothelial blebs.These blebs were found in the vessels of all sixanimals, but not in every vessel on each section,and were more prominent in the arterioles thanin the venules or capillaries.A less striking finding, but one noted in mostevery vessel on each section of all six animals,was the appearance of surface-type blebs(figures 7 and 8). These blebs can be very simi-lar to the fingerlike protrusions into the lumenfound in the controls except that the distal endwas always more dilated than the proximalportion. This dilation of the distal end variedgreatly from a small dilation containing onlycytoplasm (figure 7) to a large dilation withvacuolization (figure 8).

The least common finding was the appearanceof dilated endoplasmic reticulum in the endo-thelium (figure 9). This was found in only three !of the six animals and in only a few of thecapillaries from these three. Thickened basal jlamina and collagen changes were not demon-strable in any vessels from any animal.

Figure 6. A close up of figure 4 with vacuole-type endot-helial blebs (VB) and normal endoplasmic reticulum(ER). MAG 23,217.

Figure 5. An arteriole from a fetus whose mother wasexposed to smoke showing vacuole-type endothelialblebs (VB), a pericyte (P), and an endothelial nucleus(N). MAG 7194.

Figure 7. An arteriole from a study fetus showing avacuole-type endothelial bleb (VB) and a surface-typebleb (SB) that is finger-like but having a dilated distalportion. MAG 10,572.



Strict attention to gender was not taken duringthis study. However, on review of the data itwas noted that in the last litter of both thesmoke-exposed and control groups, gender was

Figure 8. A capillary from a study animal with surface-type blebs (SB) that are vesicular in the distal portion.MAG 10,572.

Figure 9. An arteriole from a smoke-exposed fetus withdilated endoplasmic reticulum (ER) in the endothelium.Mature red blood cells (RBC) and an immature redblood cell (I) are visible within the lumen. MAG 7194.

assigned and one male and one female pup weretaken for study in each of the litters. Both thefemale and male pups of the smoke-exposedgroup had surface and vacuole type blebs andneither had dilated endoplasmic reticulum.

4 Discussion

Sub-endothelial blebs have been found in theaortas of adult rats exposed to cigarette smokeand in adult rabbit aortas exposed to carbonmonoxide [8, 11]. Similar blebs have been de-scribed as present in umbilical veins in humanswhose mothers smoked [3]. These have beenthought to be secondary to edema or to macro-phage degeneration [3, 8, 11]. The vacuole-typeendothelial blebs described in this paper appearvery similar to the sub-endothelial blebs exceptthat they are located within the endothelialcytoplasm. The location of the blebs within andnot below the cytoplasm may be the differencein the response of fetal tissue versus adult tissue,or it may represent an earlier stage of the sameprocess. It could be expected that fetal tissuemay respond differently than adult tissue be-cause the fetal tissue is undergoing a differentia-tion process while it is being exposed to thetoxic substances, and the blood levels of thetoxic substances in the fetus may be very dif-ferent from those in the mother [13]. However,the vesicles found in our study are so similarto previously described blebs that the possibilityof their representing a different time period ofthe same process is very plausible.Focal areas of "ruffled" endothelium, areaswith numerous cytoplasmic projections, havebeen found in the aortic arches of rabbits ex-posed to nicotine [7]. Actual blebbing, wherethe neck of the projection is much smaller thanthe distal portion, has been found in theplacental and umbilical vessels of human fetus-es whose mothers smoked during pregnancy [1,2, 4, 5]. The surface-type blebbing found in thisstudy varied greatly in appearance and was, inthe one extreme, similar to that found in theruffled area and, in the other extreme, similarto that found in the placental and umbilical



vessels. The variability of the surface blebbingmay represent different time periods of the sameprocess. The blebs that have vacuoles maybe the end stage as these were the type seenin human studies during which fetuses wereexposed to the toxin 270 days. The club shapedblebs may be the earlier stage as these aresimilar to the cytoplasmic projections foundin adult rat aortas in studies exposing rats tonicotine for about half of that time. Anotherexplanation for the variability is that the mousefetal endothelium is responding to the nicotinewith excessive numbers of cytoplasmic projec-tions, and the swelling of the distal portion iscaused by other toxic products of smoking such

v as carbon monoxide [6].Dilated endoplasmic reticulum has been foundin umbilical arteries of human fetuses whosemothers smoked during pregnancy [1, 4]. Be-cause this finding has only been noted in fetusesand not in adults, dilated endoplasmic retic-ulum of the endothelium may be a response tosmoking that is limited to fetal tissue. Thismay be due to the difference in blood levels,metabolic processes, or maturity of the cells.The smaller mean weight of the smoke-exposedpups is to be expected as this finding is consis-tently present in human studies of smoking inpregnancy [10]. Since the feed consumption, theamount of handling, and the housing condi-tions of the smoke-exposed group and the con-trols were the same, it is very difficult to at-tribute the weight differences to these factors.

Therefore, the vascular changes seen in thefetuses of smoke exposed mothers may possiblybe related to the weight difference. One cantheorize that the vascular changes may affectthe transendothelial transfer of nutrients andmetabolites, thus interfering with maximal fetalgrowth [12].Sex-related differences in the fetal developmentof other tissues have been reported [14]. In thisstudy gender assignment was not given in allthe subjects, therefore, some of the changesseen may be due to developmental differencesin the sexes. However, the finding of both typesof blebs in both the female and the male smoke-exposed pups suggests that these changes arenot sex-related. Since the dilated endoplasmicreticulum was seen in smoke-exposed animalswhere gender was not assigned, the effect ofsex-related developmental differences causingthe changes rather than the smoke exposure isup to question.In all previous smoking-related fetal studies,the vessels (placental and umbilical) that wereexamined for pathologic changes were thosethat were initially exposed to the noxious stim-uli [1—5]. In this study, similar pathologic ul-trastructural changes were found in fetal vesselsfar removed from the point of noxious transfer.This tends to support the concept that smokingduring pregnancy not only affects the fetus inutero and perinatally but may initiate processesthat make it more susceptible to diseases inlater life [2, 4].

Summary

Ultrastructural changes have been found in umbilical cigarettes per day. Similarly caged mice of the samestrain were used as controls. The female mice were notremoved from their cage from pre-conception time untilafter delivery. Upon delivery each pup was sacrificed vianeck fracture and the entire pup was immersed in asolution of 2.5% gluteraldehyde in 0.1 M cacodylatebuffer at pH 7.3. While still under solution, the rear legmuscles were dissected free, sliced, and immersed in thesame preservative for four to five hours. They were thenplaced in fresh 2.5% gluteraldehyde mixture overnight.The tissues were post-fixed in osmium ferrocyanide anden-block stained with uranyl acetate in a graded series

blood vessels, placental blood vessels, and peripheralblood vessels of human fetuses whose mothers smokedduring pregnancy. This study was undertaken to deter-mine if similar changes could be found in peripheralblood vessels of mice fetuses whose mothers were ex-posed to cigarette smoke during pregnancy.Breeding mice of the C57BL/KsJ strain were placed ina smoking box similar to that described by YOUNOSZAI[12] and exposed to cigarette smoke intermittently. Thisproduces carbon monoxide levels in the adult mice simi-lar to that found in human adults smoking one pack of



of alcohol. The tissues were infiltrated with and embed-ded in Spurr. Sections were taken via an ultramicrotomeand post-stained with uranyl acetate and lead citrate.The sections were examined in a Philips 201 electronmicroscope at 60 KV.In the peripheral vessels of the fetuses from smoke-exposed mothers, endothelial blebbing (both surface-type and vacuole-type) was seen. In addition, dilatedrough endoplasmic reticulum was found in these vessels.These findings were not demonstrable in the controlfetuses. Surface-type blebs, dilated RER, thickened ba-sal lamina, and collagen changes have been found in theumbilical blood vessels of human fetuses whose motherssmoked during pregnancy. Vacuole-type endothelial

blebs have been seen in the aortas of adult rats exposedto cigarette smoke. Carbon monoxide exposure alonehas produced similar vacuole-type endothelial blebs inthe rat aorta. In all of the previous fetal studies thevascular changes were seen in vessels (umbilical andplacental vessels) that initially received the blood thatwas exposed to noxious effects of cigarette smoking.This is the first known report of finding changes invessels far removed from the point of noxious transferin fetuses and tends to support the concept that smokingduring pregnancy not only affects the fetus in utero andperinatally but may initiate processes that make it moresusceptible to diseases in later life.

Keywords: Arteries, blood vessels, carbon monoxide, cigarette, electron microscopy, fetal morphology, maternal,passive smoking, toxic effects, ultrastructural abnormalities.

Zusammenfassung

Einfluß maternaler Zigarettenrauchexposition auf die Ul-trastruktur fetaler, peripherer Blutgefäße bei der MausBei Feten, deren Mütter in der Schwangerschaft rauch-ten, wurden ultrastrukturelle Veränderungen an denUmbilikalgefaßen, den plazentaren Gefäßen sowie denperipheren Blutgefäßen gefunden. Ziel dieser Studie warfestzustellen, ob bei Mäusefeten, deren Muttertiere Ziga-rettenrauch ausgesetzt waren, ähnliche Veränderungenan den peripheren Blutgefäßen zu beobachten waren.Trächtige Mäuse eines bestimmten Stamms (C57BL/KsJ) wurden in eine Raucherbox gesetzt (ähnlich wiebei YOUNOSZAI [12] beschrieben) und intermittierend Zi-garettenrauch ausgesetzt. Der Kohlenmonoxydspiegelbei den adulten Mäusen war vergleichbar mit den Spie-geln bei Erwachsenen, die pro Tag eine Schachtel Ziga-retten rauchen. Als Kontrollen wurden Mäuse der glei-chen Zellinie benutzt, die in ähnlichen Käfigen unterge-bracht waren. Die weiblichen Mäuse blieben in denKäfigen von der Zeit vor der Konzeption bis nach demWerfen. Dann wurden die jungen Mäuse durch Frakturder Halswirbelsäule getötet und der gesamte Wurf in eineLösung aus 2,5%igem Gluteraldehyd in 0.1 molaremCacodylat-Puffer mit einem pH von 7.3 gebracht. Nochin der Lösung wurden die Muskeln der hinteren Extremi-täten freigelegt, Schnitte angelegt und in der gleichenLösung für 4—5 Stunden belassen. Danach wurden siein einer frischen 2,5%igen Gluteraldehydlösung überNacht aufbewahrt. Das Gewebe wurde in Osmium-Fer-rocyanid fixiert und en bloque mit Uranylacetat in Alko-holbädern abgestufter Konzentration gefärbt. Nach Ein-bettung wurden mit einem Ultramikrotom Schnitte an-gelegt sowie eine Nachfärbung mit Uranylacetat und

Bleicitrat vorgenommen. Die Schnitte wurden mit demPhilips-201 -Elektronenmikroskop bei 60 kV ausgewer-tet.In den peripheren Gefäßen von Feten, deren Muttertiererauchexponiert waren, zeigten sich endotheliale Aufblä-hungen sowohl vom Oberflächentyp wie auch vom Va-kuolentyp. Zusätzlich war in diesen Gefäßen das rauheendoplasmatische Retikulum (RER) dilatiert. Bei denKontrolltieren fanden sich solche Veränderungen nicht.Oberflächenaufblähungen, diktiertes RER, verdickteBasallamina und Kollagenveränderungen wurden inUmbilikalgefaßen von menschlichen Feten, deren Müt-ter während der Schwangerschaft geraucht hatten, be-schrieben. Bei rauchexponierten adulten Ratten wurdenin der Aorta endotheliale Aufblähungen vom Vakuolen-typ beobachtet. Wurden die Ratten ausschließlich Koh-lenmonoxyd ausgesetzt, entstanden in der Aorta ver-gleichbare endotheliale Aufblähungen vom Vakuolen-typ. In allen vorangegangenen Untersuchungen an Fetenwurden vaskuläre Veränderungen in umbilikalen undplazentaren Gefäßen beschrieben, also dort, wo der ersteKontakt mit dem Blut, das der Noxe Zigarettenrauchausgesetzt war, stattfindet. In der vorliegenden Studiewerden zum ersten Mal Veränderungen an peripherenGefäßen erfaßt, also nicht nur dort, wo der Transfer derNoxe erfolgt. Hiermit wird die Hypothese unterstützt,daß Rauchen in der Schwangerschaft nicht nur denFeten in utero beeinträchtigt und perinatale Auswirkun-gen hat. Vielmehr können Prozesse initiiert werden, diemit einer erhöhten Morbidität im späteren Leben einher-gehen.

Schlüsselwörter: Arterien, Blutgefäße, Elektronenmikroskopie, fetale Morphologie, Kohlenmonoxyd, mütterlicheMorphologie, passives Rauchen, toxische Effekte, ultrastrukturelle Anomalien, Zigaretten.



Resume

Effet de Pexposition au tabagisme maternel sur Pultras-tructure des vaisseaux sanguins peripheriques du fetuschez la sourisOn a trouve des modifications ultrastructurales au ni-veau des vaisseaux sanguins ombilicaux et des vaisseauxperipheriques chez des foetus humains dont les meresfumaient pendant la grossesse. Cette etude a ete entrepri-se afin de determiner si pouvait trouver des modifi-cations similaires au niveau des vaisseaux peripheriquesde foetus de souris dont les meres avaient ete exposees ala fumee de cigarette pendant la gestation.Des souris gestantes de la lignee C57BL/KsJ ont eteplacees dans une boite «ä fumee» similaire ä celle decritepar YOUNOSZAI* [12] et ont ete exposees par intermittencea la fumee de cigarette. Ce procede entraine des taux demonoxide de carbone chez les souris adultes similairesa ceux que trouve chez les adultes humains qui

vfument un paquet de cigarettes par jour. Des souris dela meme lignee, mises en cage de la meme fagon ontservi de contröles. On n'a pas sorti les femelles de leurcage depuis le moment avant la conception jusqu'apres1'accouchement. Lors de la naissance, chaque souriceaua ete sacrifie par fracture cervicale et le souriceau entieretait plonge dans une solution de gluteraldehyde a 2,5%avec un tampon de cacodylate 0,1 M ä pH 7,3. Lesmuscles de la patte arriere etaient disseques toujoursdans la solution, puis on les decoupait et on les plongeaitdans la meme solution conservatrice pendant quatre äcinq heures. Les muscles etaient ensuite places dans unesolution fraiche de gluteraldehyde ä 2,5% pendant touteune nuit. Les tissus etaient ensuite post-fixes avec unferrocyanide osmium et colores en bloc par Pacetate

d'uranyl. Les tissus s'infiltraient et Finclusion se realisait.On realisait des coupes a Faide d'un ultra^microtome etune post-coloration etait effectuee avec de Furanyl aceta-te et du citrate de plomb. Les coupes ont ete examineesä l'aide d'un microscope electroniqe Philips 201 a 60 KV.Dans les vaisseaux peripheriques des foetus, provenantde meres exposees a la fumee, on voit des bulles endothe-liales (de deux types: de surface et vacuolaire). En outre,on trouve dans ces vaisseaux une dilatation du reticulumendoplasmique rugueux. Ces elements n'ont pas ete re-trouves chez les foetus contröles. On a trouve dans lesvaisseaux ombilicaux de foetus humains dont les meresavaient fume pendant la grossesse, des bulles de surface,un RER dilate, un epaississement de la lame basale, etdes modifications du collagene. On a observe des bullesendotheliales de type vacuolaire au niveau de Paorte derats adultes exposes a la fumee de cigarette. L'expositionau monoxyde de carbone seul entraine des bulles endot-heliales similaires de type vacuolaire au niveau de 1'aortede rat. Dans toutes les etudes foetales anterieures, lesmodifications vasculäires ont ete observees au niveaudes vaisseaux (vaisseaux ombilicaux et placentaires) quire^oivent en premier le sang qui a ete expose aux effetsnocifs de la fumee de cigarettes. Ce rapport est le premierconnu a avoir trouve des modifications au niveau de

, vaisseaux tres eloignes du point transfer nocif chez lesfoetus et ce rapport tend ä appuyer le concept que letabagisme au cours de la grossesse n'affecte pas seule-ment le foetus in utero et en periode perinatale mais qu'ilpeut initier des processus qui pourront le rendre plussujet a certaines maladies au cours de sa vie ulterieure.

Mots-cles: Anomalies ultrastructurales, arteres, cigarettes, effets toxiques, fumeur passif, maternel, microscopeelectronique, monoxyde carbone, morphologic foetale, vaisseaux sanguins.

References

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[2] ASMUSSEN I: Ultrastructure of the human placentaat term. Acta Obstet Gynecol Scand 56 (1977) 119

[3] ASMUSSEN I: Ultrastructure of human umbilicalveins. Acta Obstet Gynecol Scand 57 (1978) 253

[4] ASMUSSEN I: Arterial changes in infants of smokingmothers. Postgrad Med J 14 (1978) 200

[5] ASMUSSEN I: Ultrastructure of the villi and fetalcapillaries in placentas from smoking andnonsmoking mothers. Br J Obstet Gynaecol 87(1980) 239

[6] ASTRUP P, K KJELDSEN: Model studies linking car-bon monoxide and/or nicotine to arteriosclerosisand cardiovascular disease. Prev Med 8 (1979) 295

[7] BOOYSE FM, G OSIKOWICZ, AJ QUARFOOT: Effectsof chronic oral consumption of nicotine on therabbit aortic endothelium. Am J Pathol 102 (1981)2f29

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[11] KJELDSBN K, P ASTRUP, J WANSTRUP: Ultrastructu-ral intimal changes in the rabbit aorta after a mo-derate carbon monoxide expose. Atherosclerosis 16(1972) 67

[12] YOUNOSZAI MK, J PELOSO, JC HAWORTH: Fetalgrowth retardation in rats exposed to cigarettesmoke during pregnancy. Am J Obstct Gynecol 104(8) (1969) 1207

[13] WANG IY, RE RASMUSSEN, R CRRASBY, TT CROCK-BR: Metabolites of benzo(a) pyrcne produced byplacental microsomcs from cigarette smokers andnonsmokers. Life Sei 20 (1977) 1265

[14] AOAMSON IYR, GM KING: Sex differences in thedevelopment of fetal rat lung Part II. Quantitativemorphology of cpithelial-mcsochymc interactions.Lab Invest SO (1984) 461

Received January 15, 1985. Revised July 25, 1985. Ac-cepted September 30, 1985.

Robert C. Kaufmann, M. D.Assistant Professor,Division of Maternal/Fetal Medicine,Department of Obstetrics and GynecologySouthern Illinois University School of MedicineP. O. Box 3926Springfield, IL 62708, U. S. Λ.


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j. perinat. Med. The effect of maternal smoke exposure on