Chapter13 Gross Anatomy

GrossAnatomy

VladimõÂr Koma rekAgricultural University, Prague, Czech Republic

Introduction

Although this book does not aim to provide a

comprehensive description of rat anatomy, this

chapter presents illustrations of areas likely to be

of practical importance to those working with

laboratory rats. These areas include body surface,

body regions, muscles, and dissection of the neck,

thorax and abdomen with pelvic cavity.

For further anatomical details, readers are re-

ferred to Chapter 15 and the excellent works of

Green (1963), Hebel and Stromberg (1986) and

Popesko et al. (1990).

The terminology used here is based on the inter-

national veterinary anatomical nomenclature pub-

lished by Schaller et al. (1992). In the figure captions,

XY denotes male and XX female.

Acknowledgement

With her kind consent, some of the figures pre-

sented in this chapter were drawn following the

concept of Professor Dr Viera Rajtova (Popesko

et al., 1990).

References

Green, E.C. (1963) Anatomy of the Rat. New York: Hafner

Publishing.

Hebel, R. and Stromberg, M.W. (1986) Anatomy and

Embryology of the Laboratory Rat. WoÈrthsee: BioMed

Verlag.

Popesko, P., Rajtova, V. and Horak, J. (1990) Atlas anatomie

malych laboratornych zvierat, Vol. 2. Bratislava: Priroda.

(English version published by Wolfe Publishing Ltd,

London, 1992.)

Schaller, O., Constantinescu, G.M., Habel, R.E., Sack,

W.O., Simoens, P. and de Vos, N.R. (1992) Illustrated

Veterinary Anatomical Nomenclature. Stuttgart: Enke

Verlag.

Copyright # 2000 Academic Press

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Figure 13.1 The hair coat, ventral view (XY). The rat hair is arranged to formwhirls and streams (vortices et flumina pilorum).1 at the level of arm joints there are divergent whirls (vortices pilorum

divergentes)2 in the axillary region there is divergent stream (flumen pilorum divergens

axillaris)3 in the ventromedial area there is a convergent stream (flumen pilorum

convergens trunci).4 in the umbilical area there is convergent umbilical whirl (vortex pilorum

convergens umbilicalis)5 the inner surface of the thigh is separated from the caudal abdomen

(inguinal region) by divergent inguinal stream (flumen pilorum divergensinguinalis)

6 at the caudal end of the above stream there is a whirl (vortex pilorumdivergens inguinalis)

7 the ventral surface of scrotum is hairless (planum depilatum)8 preputium, penis

Figures 13.2a, b, (XY) and c (XX): The regions of rat body(regiones corporis).Regions of the face(regiones faciei)

1 regio dorsalis nasi2 regio lateralis nasi3 regio naris et apex nasi4 regio oralis5 regio mentalis6 regio buccalis7 regio mandibularis8 regio intermandibularis9 regio orbitalis

10 regio infraorbitalis11 regio zygomatica12 regio articulationis

temporomandibularis13 regio masseterica

Regions of the skull(regiones cranii)14 regio frontalis15 regio parietalis16 regio occipitalis17 regio supraorbitalis18 regio temporalis19 regio auricularis et auriculaRegions of the neck(regiones colli)20 regio parotides21 regio subhyoidea et

laryngea22 regio colli dorsalis23 regio colli ventralis24 regio trachealis

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Figures 13.2a, b, c (continued)

Regions of the breast (regiones pectoris)25 regio presternalis26 regio sternalis27 regio mammaria thoracica28 regio costalis29 regio scapularis30 arcus costalisCranial abdominal regions (regiones abdominis craniales)31 regio hypochondriaca32 regio xiphoideaMedian abdominal regions (regiones abdominis mediae)33 regio abdominis lateralis34 regio umbilicalis35 regio plicae genus36 regio mammaria abdominalisCaudal abdominal regions (regiones abdominis caudales)37 regio inguinalis38 regio pubica (scroti et preputialis in XY)39 regio mammaria inguinalis

Dorsal regions (regiones dorsi)40 regio vertebralis thoracis41 regio interscapularis42 regio lumbalisPelvic regions (regiones pelvis)43 regio sacralis44 regio tuberis coxae45 regio glutea46 regio clunis47 regio tuberis ischiadici48 regio radicis caudae49 regio corporis caudae50 regio apicis caudae51 regio perinealis52 regio analis53 regio vulvae (XX)54 regio clitoridis (XX)Regions of the thoracic extremity (regiones membrithoracici)55 regio articulationis humeri56 regio axillaris57 regio brachii58 regio tricipitalis59 regio cubiti60 regio antebrachii (cranialis, lateralis, caudalis,

medialis)61 regio carpi (cranialis, lateralis, caudalis, medialis)62 regio manus (metacarpi et digiti, dorsalis, lateralis,

volaris/palmaris, medialis)Regions of the pelvic extremity (regiones membri pelvini)63 regio articulationis coxae64 regio femoris (cranialis, lateralis, caudalis, medialis)65 regio genus66 regio cruris (cranialis, lateralis, caudalis, medialis)67 regio tarsi (cranialis, lateralis, caudalis, medialis)68 regio pedis (metatarsi et digiti, dorsalis, lateralis,

plantaris, medialis)

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Figure 13.3 Palmar (volar) surface of the right frontal paw(facies palmaris (volaris) manus dextri).

1 regio carpi palmaris (volaris)2 regio antebrachii3 regio cubiti

4 regio metacarpi palmaris (volaris)5 regio metacarpophalangea6 regio phalangis proximalis7 regio interphalangea proximalis8 regio phalangis mediae9 regio unguiculae et regio interphalangea distalis

10 spatia interdigitalia11 toruli digitales12 tori metacarpales13 tori carpales14 flexus cutis (in thoracic extremities occuring about five times)I±V digitus primus, secundus, tertius, quartus, quintus

Figure 13.4 Plantar surface of the right caudal paw (facies plantaris pedis dextri).1 regio tarsi plantaris2 regio cruris3 regio genus4 regio metatarsi plantaris5 regio metatarsophalangea6 regio phalangis proximalis7 regio interphalangea proximalis8 regio phalangis mediae

9 regio unguiculae10 spatia interdigitalia11 toruli digitales12 tori metatarsales13 tori tarsales14 flexus cutisI±V digitus primus, secundus, tertius,

quartus, quintus

Figure 13.5 Scales on the tail. The tail is covered by squarescales, underneath which grow two to six straight hairs,extending over the next row of scales.

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Figure 13.6 The mammary gland (XX). The mammary tissue isdistributed bilaterally, reaching from the neck to the anus.In males the nipples do not develop well.1 cervical mammary gland, devoid of nipples2 thoracic mammary gland usually has three pairs of nipples;

it does not cover the sternum, but fills the axillary region,surrounds partly the basis of forelimbs and extends towardsthe costal region

3 abdominal mammary gland has only little, irregularlydeveloped tissue

4 inguinal mammary gland usually has three pairs of nipplesand is located in the inguinal region, partly surrounding thebasis of hindlimbs

5 clitoral preputium is equipped with a paired clitoral gland.In female rats the urethra opens at the clitoris so that thereis no vaginal vestibulum

6 vaginal entrence (vulva) has small labia7 anus

Figure 13.7 The superficial muscles. (See also Colour Plate 1.)1 musculi faciales2 musculus temporalis3 musculus masseter4 glandula lacrimalis extraorbitalis5 glandula parotidea with the ventral auricular muscle6 glandula mandibularis7 musculus sternocephalicus, pars mastoidea8 musculus brachiocephalicus, pars occipitalis9 musculus deltoideus, pars acromialis

10 musculus deltoideus, pars scapularis11 musculus trapezius, pars cervicalis12 musculus trapezius, pars thoracica13 musculus cervicoauricularis14 musculus latissimus dorsi15 musculus cutaneus trunci16 musculus serratus ventralis thoraci17 musculus obliquus externus abdominis18 musculus tensor fasciae latae19 musculus quadriceps

femoris, musculusrectus

20 musculus gluteussuperficialis

21 musculus biceps femoris,portio cranialis et caudalis

22 musculus semitendinosus23 musculus gastrocnemius,

caput laterale24 musculus tibialis

cranialis25 musculus extensor

digitorum longus

26 musculus triceps brachii,caput laterale

27 musculus triceps brachii, caput longum

28 musculus biceps brachii

29 musculus brachialis

30 musculi extensores carpi etdigitorum

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Figure 13.8 The deep muscles, forelimb removed. (See also Colour Plate 2.)1 glandula parotidea2 glandula and lymphonodus

mandibularis3 lymphonodus retropharyngeus

4 lymphonodus cervicalisprofundus

5 vena jugularis6 plexus brachialis7 arteria et vena subclavia

8 musculus sternocephalicus, parsmastoidea

9 musculus brachiocephalicus,pars occipitalis

10 clavicula11 musculi pectorales

12 musculus rectus thoracis etabdominis

13 musculus rhomboideus capitis14 musculus rhomboideus cervicis15 musculus splenius16 musculus longissimus capitis et

atlantis17 corpus adiposum nuchae

(multivesiculare s. plurivacuolares. hiberneticum)

18 musculus longissimus cervicis19 musculus longissimus thoracis20 musculus longissimus

lumborum21 musculus serratus ventralis

(cervicis et thoracis)22 musculus serratus dorsalis

cranialis23 musculus serratus dorsalis

caudalis24 musculus iliocostalis25 musculi intercostales externi26 musculus obliquus externus

abdominis27 musculus obliquus internus

abdominis28 musculus gluteus medius29 musculus quadriceps femoris30 musculus biceps femoris31 musculus semimembranosus et

semitendinosus32 musculus tibialis cranialis33 musculus triceps surae

Figure 13.9 Locations of lymph nodes.Does not include those drainingspecific viscera such as gastrointestinal,respiratory and urogenital system.See Chapter 28 for details aboutthe lymph nodes draining particularbody areas.

1 lymphonodi mandibulares2 lymphonodi cervicales

superficiales3 lymphonodi cervicales

profundi4 lymphonodi sternales

craniales5 lymphonodi mediastinales ventrales6 lymphonodi mediastinales dorsales

(et thymus)7 lymphonodi axillares proprii8 lymphonodus axillaris accessorius9 lymphonodi thoracici aortici

10 lymphonodi renales11 lymphonodus cisternalis12 lymphonodi lumbales aortici13 lymphonodus iliacus lateralis14 lymphonodus iliacus medialis15 lymphonodus sacralis16 lymphonodus ischiadicus17 lymphonodus popliteus18 lymphonodi subiliaciThe trachea is accompaniedby truncus trachealis andthe (abdominal) aorta bytruncus lumbalis, whichjoins with truncusintestinalis, producingcisterna chyli, from whichtruncus thoracicus leadstowards the heart.

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Figure 13.10 Ventral view of the head.1 labium maxillare pars externa2 labium maxillare pars interna3 palatum durum4 glandulae mentales

Figure 13.11 Subcutaneous organs of the ventral neck, ventral view (organa subcutanea colli ventralis, norma ventralis).(See also Colour Plate 3.)1 lymphonodi mandibulares and deep underneath, close to the

atlas lymphonodi retropharyngei2 lymphonodi cervicales superficiales3 glandula lacrimalis extraorbitalis4 glandula parotis5 glandula sublingualis major et ductus glandulae sublingualis

and deep underneath glandula thyreoidea et parathyreoidea.Caudally to them lymphonodi cervicales craniales

6 glandula mandibularis et ductus glandulaemandibularis (also called submandibular)

7 musculus masseter et ductus parotideus8 venter rostralis musculi digastrici9 musculus sternomastoideus

10 musculus sternohyoideus11 musculus pectoralis major12 vena jugularis externa dextra

Figure 13.12 Organs of the ventral neck, ventral view,deep layer (organa colli ventralis, norma ventralis, stratumprofundum). (See also Colour Plate 4.)A lymphonodi mandibularesB glandula sublingualisC glandula mandibularis (submandibularis)D glandula parotis et lymphonodus cervicalis

superficialisE glandula thyreoidea et parathyreoideaF esophagusG trachea1 musculus sternohyoideus et sternothyreoideus

(resectus)2 musculus digastricus, venter rostralis3 musculus mylohyoideus4 musculus masseter et ductus parotideus5 mandibula6 musculus sternomastoideus7 musculus omohyoideus8 musculus pectoralis major9 vena jugularis externa

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Figure 13.13 Ventral view at the thorax, after removal of the sternum and portions of the ribs.1 platysma colli2 musculus sternomastoideus3 musculus pectoralis transversus4 clavicula grown into musculus cleidobrachialis5 trachea6 esophagus et hiatus esophageus7 open pericardium, adhering to the thoracic wall8 vena cava cranialis dextra9 vena cava caudalis et foramen venae cavae caudalis

10 hiatus aorticus

11 diaphragma, centrum tendineum12 pars lumbalis diaphragmae13 lobus cranialis pulmonis dextri14 lobus accessorius pulmonis dextri15 lobus caudalis pulmonis dextri16 pulmo sinister (pars caudalis)Co 1 costa primaCo 10 costa decima (other ribs are out of the section level)R ren dexterS glandula adrenalis dextra

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Figure 13.14 The position of the heart in the thoracic cavity, the lung removed.Co 1 costa primaCT clavicula1 d,s vena cava cranialis dextra et sinistra2 vena cava caudalis3 trachea4 esophagus5 aorta descendens et ductus thoracicus (leading to

vena cava sinistra), lymphonodi aortici, usually small6 lymphonodi sternales craniales

7 lymphonodi mediastinales ventrales8 thymus et lymphonodi mediastinales dorsales (the

thymus and the lymph nodes are displaced laterally,to uncover the heart basis over which they arenormally located)

9 lymphonodi axillares proprii et accessoriiAD atrium dextrumVD ventriculus dexterVS ventriculus sinister

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Figure 13.16 The heart, from the right side(cor, adspectus dexter).a apex cordisaa arcus aortaeaap arteriae pulmonalesb ventriculus sinisterc sulcus interventricularis subsinuosusd ventriculus dextere sulcus coronariusf sinus venarum cavarum et atrium dextrumg auricula dextravcc vena cava caudalisvccrd vena cava cranialis dextravccrs vena cava cranialis sinistravvp venae pulmonales1 truncus brachiocephalicus2 arteria carotis communis sinistra3 arteria subclavia sinistra4 aorta thoracica5 ligamentum arteriosum (Botalli)6 vena azygos sinistra7 vena subclavia dextra

Figure 13.17 Transverse sectionthrough the heart at the level of exits of large vessels.1 cavum auriculae sinistrae2 cavum ventriculi sinistri3 ostium et valva aortae4 cavum auriculae dextrae

5 cavum ventriculi dextri6 ostium et valva trunci

pulmonalis7 septum interventriculare

Figure 13.18 The heart, right ventricle opened(cor, ventriculus dexter apertus).1 valva atrioventricularis dextra (tricuspidalis), ostium

atrioventriculare dextrum shimmering through2 septum interventriculare3 ostium et valva trunci pulmonalis4 trabeculae septomarginales5 outer wall of the right ventricle, detached and deflected

Figure 13.15 The lungs removed from thethoracic cavity, together with the heart.A norma dorsalisB norma ventralisC cor1 trachea2 pulmo sinister (pars cranialis)3 pulmo sinister (pars caudalis)4 lobus cranialis pulmonis dextri5 lobus medius (cardiacus)

pulmonis dextri6 lobus accessorius pulmonis dextri

(`postcaval lobe', lobus azygos)7 lobus caudalis pulmonis dextria margo acutusb margo dorsalis (obtusus)c facies costalis

d facies medialise facies diaphragmaticaf fissura interlobaris

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Figure 13.19a,b The heart, left ventricle cut open (cor,ventriculus sinister resectus).1 valva atrioventricularis sinistra (bicuspidalis)2 septum interventriculare3 ostium et valva aortae4 musculi papillares5 ostium atrioventriculare sinistrum6 cuspis parietalis7 cuspis septalis

Figure 13.20 Ventral view of the abdominal cavity,superficial layer. Organs and tissues seen after openingthe abdominal cavity.Ce intestinum cecumG gaster (ventriculus, stomach)H hepar (liver)O saccus omenti majoris (in well-nourished individuals

exhibiting prominent adipose tissue located along thelymphatic vessels)

Figure 13.21 Ventral view of the abdominal cavity afterremoval of the omentum.Ce cecumCt colon transversumD duodenumG gasterH heparI ileumJ jejunumL lien

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Figure 13.22a,b Ventral view of the abdominal cavity (XY), cecum in right (a) or central (b) position. In some instances thececum can even be located on the left side. (See also Colour Plate 5.)

X cartilago xifoidea1 lobus hepatis dexter lateralis2 lobus hepatis dexter

medialis3 lobus hepatis

sinistermedialis

4 lobus hepatissinisterlateralis

5 fundusventriculi

6 lien (spleen)7 jejunum and

its mesenterium8 ileum9 basis ceci

10 corpus ceci11 apex ceci12 rectum13 arteria et vena

spermatica internasinistra

14 ureter sinister15 vesica urinaria,

facies dorsalis (theurinary bladder isturned over caudally)

16 glandula vesicularissinistra

17 prostata ventralis, lobusdexter

18 ductus deferens dexter19 paniculus adiposus

20 canalis inguinalis dexter21 symphysis pelvis22 glandula preputialis23 preputium

Figure 13.23 Ventral view of the gastrointestinal tract afterremoval of the jejunum.

1 esophagus et ostiumcardiacum

2 curvatura ventriculi minor3 curvatura ventriculi major4 saccus cecus

(proventriculus)5 fundus ventriculi6 corpus ventriculi7 pars pylorica ventriculi8 ostium pyloricum9 lien (spleen)

10 ductus hepatoentericus(choledochus)

11 pancreas12 flexura duodeni cranialis13 pars descendens

(duodeni)14 flexura duodeni caudalis15 pars ascendens (duodeni)

16 flexura duodenojejunalis17 jejunum18 ileum19 ostium ileocecale20 excavatio ceci21 basis ceci22 corpus ceci23 apex ceci24 ligamentum ileocecale25 curvatura ceci minor26 curvatura ceci major27 ostium cecocolicum28 colon ascendens

(with fluid contents)29 colon transversum

(with solid contents)30 colon descendens31 rectum32 anus

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Figure 13.24 The stomach opened at the large curvature toshow its mucous membranes.1 ostium cardiacum2 pars cardiaca ± saccus cecus (tela mucosa aglandularis)

the cutaneous mucosa is white-reddish, arranged innarrow circular folds which can stretch when thestomach is filled

3 margo plicatus4,5,6 telae mucosae glandulares4 pars fundica fusca (brown-red)5 pars fundica pallida (pale-brown)4,5 the mucosa forms irregular, rounded reserve folds6 pars pylorica7 torus pyloricus8 duodenum

Figure 13.25 The cecum opened at the largecurvature to show the mucous membrane.1 apex ceci2 corpus ceci3 basis ceci4 blood vessels, seen underneath the mucosa,

arrive from the small curvature5 excavatio ceci6 ostium ileocecale7 ostium cecocolicum

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Figures 13.26±13.29 The liver. (a) Facies visceralis; (b) facies diaphragmatica. The rat does not possess a gall bladder sothat the liver is connected to the duodenum by ductus choledochus (enterohepaticus). This series of figuresdemonstrates the great individual variation of hepatic lobulation in rats. Lobus quadratus is not described in rats.

1 lobus lateralis sinister2 lobus medialis sinister3 lobus medialis dexter4 lobus lateralis dexter5 processus papillaris pars preventricularis

(lobus caudatus)6 processus papillaris pars retroventricularis

(lobus caudatus)7 processus caudatus (lobus caudatus)

8 vena cava caudalis growths into the liver collecting venaehepaticae

9 at the porta hepatis, arteria hepatica and vena portae enter, andductus hepatoentericus (hepaticus communis, choledochus) exitsthe liver

10 margo dorsalis with sulcus esophagicus (impressio esophagica)11 on the facies visceralis lobi lateralis sinistri there is impressio

gastrica12 on the processus caudatus there is impressio renalis

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Figure 13.30 The spleen (lien) ± visceralsurface and transverse section (faciesvisceralis et sectio transversa lienis).1 extremitas dorsalis2 extremitas ventralis3 margo cranialis4 margo caudalis5 facies gastrica6 facies intestinalis7 facies parietalis (diaphragmatica)8 hilus lienis

Figure 13.31 Ventral view of the male urogenital tract.1 testis dexter in scroti2 ductus deferens dexter3 glandula ductus deferentis4 vesica urinaria is turned over, so that the facies dorsalis is displayed5 prostata ventralis6 prostata dorsolateralis7 glandula vesicularis8 glandula coagulationis9 musculus urethralis

10 glandula bulbourethralis11 musculus bulbocavernosus12 corpus penis13 glans penis14 preputium15 glandula preputialis16 rectum17 ren dexter et ureter dexter18 glandula suprarenalis dextra

Figures 13.26±29 (continued)

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Plate 13.32 Ventral view of the main blood vessels of the abdominal and pelvic cavity (XY). (See also Colour Plate 6.)1 aorta abdominalis2 arteriae phrenicae caudales (inferiores)3 arteria suprarenalis cranialis (superior)4 arteria celiaca5 arteria et vena renalis6 arteria et vena suprarenalis caudalis (inferior)7 arteria mesenterica cranialis (superior)8 arteria et vena testicularis have rami epididymales

et ramus testicularis where the vein forms aroundthe artery plexus pampiniformis (8')

9 arteria et vena iliolumbalis10 arteria mesentrica caudalis11 arteria et vena iliaca communis12 arteria et vena iliaca interna13 arteria et vena ductus deferentis14 vena cava caudalis15 venae hepaticaeA hiatus aorticusB foramen venae cavae caudalisC glandula suprarenalis (adrenalis) sinistraD ren sinisterE ureter sinisterF vesica urinariaG ductus deferens sinisterH urethra

Figure 13.33 Location of the male genital organs viewed from the left.1 testis dexter in scroti2 ductus deferens dexter3 glandula ductus deferentis4 vesica urinaria5 prostata ventralis6 prostata dorsolateralis7 glandula vesicularis8 glandula coagulationis9 musculus urethralis

10 glandula bulbourethralis11 musculus bulbocavernosus12 corpus penis13 glans penis14 preputium15 glandula preputialis16 rectumS1 os sacrum

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Figure 13.34 Testis in scrotum, dorsal view (testis in scroti, aspectus dorsalis).1 testis dexter2 caput epididymidis3 corpus epididymidis4 cauda epididymidis removed from the scrotum to

demonstrate its relatively large size, obviouslyrelated to high fertility of rodents

5 ductus deferens dexter6 funiculus spermaticus, arteria, vena et nervus

spermaticus internus, et musculus cremaster internus7 paniculus adiposus which maintains the widths of

canalis inguinalis (8) and enables easy translocationof the testicle between the abdominal cavity and scrotum

8 canalis inguinalis9 ligamentum testis proprium

10 mesorchium11 septum scroti

Figure 13.35 Glans nudus penis et crura penis ischiadica.1 processus urethrae et orifitium urethrae externum2 pars libera penis3 lamina interna preputii4 anulus preputialis5 lamina externa preputii6 cutis resecta7 glandulae preputiales8 corpus penis9 crura penis attached to arcus ischiadicus (radix penis)

10 urethra entering the penis from the pelvic cavity

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Figure 13.36 Ventral view of the main blood vessels of the abdominal and pelvic cavity (XX). (See also Colour Plate 7.)1 aorta abdominalis2 arteriae phrenicae caudales (inferiores)3 arteria suprarenalis cranialis (superior)4 arteria coeliaca5 arteria et vena renalis6 arteria et vena suprarenalis caudalis (inferior)8 arteria et vena ovarica have ramus ovaricus,

ramus tubarius et ramus uterinus9 arteria et vena iliolumbalis

10 arteria mesentrica caudalis11 arteria et vena iliaca communisA hiatus aorticusC glandula suprarenalis sinistraD ren sinisterE ureter sinisterI ovarium sinistrumJ uterus

Figure 13.37 Ventral view of the abdominal cavity of anonpregnant female. The gastrointestinal tract is removedand the veins are not depicted. (See also Colour Plate 8.)

1 rectum et anus2 vesica urinaria, facies dorsalis ± turned over, so that it

covers introitus vaginae et clitoris3 vagina4 cervix uteri5 uterus dexter6 ovarium dextrum7 ureter dexter8 ren dexter9 glandula suprarenalis (adrenalis) dextra

10 colon descendens11 arteria suprarenalis cranialis sinistra12 arteria celiaca13 arteria renalis dextra14 arteria suprarenalis caudalis sinistra15 arteria mesenterica caudalis16 arteria ovarica dextra17 ramus uterinus dexter18 arteria circumflexa ilium profunda19 arteria mesenterica caudalis20 arteria iliaca communis sinistra21 cartilago xiphoidea22 diaphragmaA aorta abdominalisE hiatus esophagicusV foramen venae cavae caudalis

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Figure 13.38 Vagina simplex, dorsal median section, dorsal view(vagina simplex, sectio mediana dorsalis, adspectus dorsalis).1 introitus vaginae2 corpus vaginae3 portio vaginalis cervicis4 canales cervicis uterorum

et portio prevaginalis cervicis5 uterus duplexS uterus sinisterD uterus dexter

Figure 13.39 Position of the pregnant uterus,day 11 of pregnancy, view from the left.

L6 vertebra lumbalis VIS os sacrum1 anus2 introitus vaginae3 clitoris et ostium urethrae externum4 glandulae clitoridis5 symphysis pelvis et m. gracilis6 rectum7 vagina8 cervix uteri9 uterus sinister with embryos

10 ren sinister et ovarium cum oviducti11 ureter sinister12 vesica urinaria13 urethra feminina et musculus urethralis

Figure 13.40 Shape of the abdomen of pregnant female,day 19 of pregnancy, ventral view with indication of theextent of the mammary gland. At this stage, the abdomenis the most voluminous part of the body. The abdominalcavity is mostly filled by the pregnant uterus, whereas theother organs, such as the intestines, stomach, spleen andliver are squeezed into the diaphragm. The gastrointestinaltract has little content. The body length of the animal usedfor this preparation is indicated, (0/21cm) as are thesection levels of the following Figures 13.41±13.48 (41±48).These transverse sections are presented as caudal views.A anusB pudendum femininumC clitoris et ostium urethrae externum

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Figure 13.41 Transverse section at the level of the first caudal vertebrae (scale = 1 cm).A rectumB vaginaC urethraD fascia et tela pelvis1 muscles of the tail2 musculus biceps femoris3,4 musculi semitendinosus et semimembranosus5 caudal muscles of the leg (extensors of the tarsus

and flexors of the toes)6 dorsal muscles of the leg (extensors of the toes

and flexors of the tarsus)7 muscle of the clitoris8 ossa cruris (tibia and fibula grown together)

Figure 13.42 Transverse section at the level of the pelvis caudally tothe acetabulum (scale = 1 cm).A rectumB cranial end of the vagina

with opening of the left andright uterus (portiovaginalis cervicis ± ostiauteri sinistri et dextriexterna)

C urethraD os sacrumE os ischiiF symphysis pelvisG ossa crurisHI uterus sinister (fetus I)

J paniculi adiposiK mamma1 dorsal, lateral and ventral

muscles of the tail2 musculus biceps femoris3,4 musculi semitendinosus

et semimembranosus5 caudal muscles of the leg6 dorsal muscles of the leg7 abdominal wall8 musculus gracilis9 musculi obturatorii

10 musculus adductor

Figure 13.43 Transverse section at the level of acetabulum(scale = 1 cm).A colon descendensB articulatio coxaeC femur (epiphysis distalis)D os sacrumHI uterus sinister (fetus I)HII uterus sinister (fetus II)J paniculi adiposiK mammaLI uterus dexter (fetus I)1 dorsal, lateral and ventral muscles of the tail2 abdominal wall3 musculus quadriceps femoris

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Figure 13.44 Transverse section 6 cm cranial to anus(scale = 1 cm).A colon descendens,

above it are aortaabdominalis et venacava caudalis

B vertebra lumbalissurrounded by thelong muscles of theverebral column

D abdominal wall

H uterus sinister (fetus I,II, III)

J paniculi adiposiK mammaL uterus dexter (fetus I)M placenta discoidea

(disciformis)S intestinum

Figure 13.45 Transverse section 7.5 cm cranial to anus(scale = 1 cm).A colon descendens et

flexura coli, above itare aorta abdominaliset vena cava caudalis

B vertebra lumbalisD abdominal wallH uterus sinister (fetus III,

IV, V)

J paniculi adiposiK mammaL uterus dexter (fetus II,

IV, V, VI)M placenta discoideaS intestinum tenue

Figure 13.46 Transverse section 9 cm cranial to anus(scale = 1 cm).A colon transversumB vertebra lumbalis

surrounded by thelong muscles of thevertebral column

C aorta descendens etvena cava caudalis

D abdominal wall

H uterus sinister (fetusIV, V)

J paniculi adiposiL uterus dexter (fetus III,

IV, V, VI)M placenta discoideaS intestinum tenue

Figure 13.47 Transverse section 10 cm cranial to anus, atthe level of the left kidney (scale = 1 cm).A aorta descendens

(abdominalis) et venacava caudalis

B vertebra lumbalissurrounded by thelong muscles of thevertebral column

C ren sinister

D abdominal wallH uterus sinister (fetus V)J paniculi adiposiL uterus dexter (fetus V

et VI)M placenta discoideaS intestinum tenue

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Figure 13.48 Transverse section 11.3 cm cranial to anus,at the level of the right kidney (scale = 1 cm).A aorta descendens

(abdominalis)et vena cavacaudalis

B first lumbarvertebrasurroundedby the longmuscles ofthe vertebral column

C abdominal wallD ren dexterE cecumF colon transversumG heparJ paniculi adiposi

K mammaL uterus dexter

(fetus VI)N gasterO diaphragma

Figure 13.49 Uterus, day 20 of pregnancy, ventral viewafter opening the abdomen in the midline (scale = 5 cm).A cartilago xiphoideaB lobi hepaticiC intestinum tenueD intestinum cecum,

detached andremoved

E paniculusadiposus

UD uterus dexter(contains 5 fetuses,1 XX and 4 XY)

US uterus sinister(contains 8 fetuses,4 XX and 4 XY)

Figure 13.50 Lateral view of a fetus (scale = 1 cm).The eyelids are closed, the ears not fully developed,the nostrils almost imperceptible and the mouthappears to be closed. The skin is hairless, only on themuzzle are shadows of future sinus hairs.

The arrows are directed towards the head of each fetus; theheads are mostly, but not always directed to the vagina.

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Figure 13.51 Diagram of the pregnant uterus in transverse section.1 uterine wall2 fetus3 umbilical cord4 amnion5 amniotic fluid6 placenta discoidea

Figure 13.52a,b Sexual differentiation. In males (a) the distance between the anus and preputium is shorter (about2 mm) than in females (b) (about 3 mm). Moreover, in females the labia and the introitus vaginae are indicated.

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