UTERUS (DEVELOPBIENT). 



most densely and closely united towards the 

 inner and outer surfaces, but to be more easily 

 separable in the centre or vascular layer, 

 where the laminae are connected by a looser 

 fibrous tissue, and are everywhere permeated 

 by numerous large and small venous canals. 

 These laminae are superimposed the one upon 

 the other, in layers parallel with the two sur- 

 faces of the uterine walls, but neither the 

 laminae themselves, nor the fibres composing 

 them, can be said to take any definite course. 

 Within the laminae the fibres are arranged in 

 flat bundles, which cross in all directions, as 

 in the unimpregnated organ, but can seldom 

 be traced in the same direction for any con- 

 siderable distance. This is especially the 

 case in the middle or vascular layer. In the 

 superficial laminae, the tendency of the fibres 

 is to converge towards the angles to which 

 the appendages are attached, while internally 

 an apparent disposition to the formation of 

 concentric circles around the orifices of the 

 Fallopian tubes has been sometimes observed 

 upon inverting the organ after labour. But 

 nothing like a continuous arrangement of 

 muscular fibres in the form of circular or 

 longitudinal bands surrounding or investing 

 the organ, can anywhere be demonstrated by 

 the aid of the microscope. 



The blood-vessels of the uterus undergo a 

 marked increase in length, and especially in 

 breadth, during pregnancy. The arteries pur- 

 sue a remarkable spiral course whilst tra- 

 versing the uterine walls. The veins form 

 flattened channels between the muscular la- 

 minae. The enlargement of the latter is ac- 

 companied partly by a growth of the muscular 

 fibre cells already existing in their tunica 

 media before pregnancy, and partly by a trans- 

 formation of their inner and outer coats. 

 Kdlliker has observed, that in the fifth and 

 sixth month, the fibres of the middle coat un- 

 dergo an enlargement as considerable as those 

 of the uterine walls, so that between these 

 two scarcely any difference can be discerned. 

 But besides these, both the inner coat, from 

 the epithelium outwards, and the outer coat, 

 acquire muscular fibres, which, except that 

 they take a longitudinal direction, do not 

 otherwise differ from those of the middle 

 coat. This structure is found in the trunks 

 of the uterine veins within the broad ligament, 

 in the internal spermatics, and in all the veins 

 of the uterine substances, which exceed 2'" 

 in diameter. In the smaller veins the muscu- 

 lar layer becomes less developed. Still, in 

 those of "' in diameter, a longitudinal layer 

 of muscular fibre next the epithelium mav be 

 found. The only exceptions consist of those 

 veins which, in the placental region, penetrate 

 the inner layers of the uterus, to become con- 

 tinuous with the maternal veins of the pla- 

 centa. These, notwithstanding their great 

 width, instead of containing three, possess 

 only one layer of muscular fibre, which, toge- 

 ther with the epithelium, composes the entire 

 coat of the vein.* 



* Siebold and Kblliker's Zeitschrift, foe. cit. p. 84. 



651 



Do the nerves of the uterus enlarge or mul- 

 tiply during pregnancy? This question, which 

 once excited much controversy, has lost its 

 chief physiological interest, since it has been 

 determined that if any enlargement of the 

 uterine nerves take place during pregnancy, 

 this is nearly or entirely confined to the 

 neurilemma, or fibrous nerve sheaths. Upon 

 this point all observers are nearly or entirely 

 agreed. Dr. Robert Lee states*, that whilst 

 engaged in making dissections of the gravid 

 uterus, he " discovered that the neunilemma 

 was the constituent tissue of the ganglia and 

 nerves which chiefly enlarged during preg- 

 nancy." Dr. Hirschfeld remarks, " this in- 

 crease of volume does not occur in the 

 nervous tubules, but in the neurilemma." M. 

 Jobert de Lamballe having traced the nerves 

 of the uterus in man and animals, both 

 in the unimpregnated and gravid state, says, 

 that he " never observed any modification 

 of their physical condition. They appeared 

 more voluminous in consequence of an in- 

 filtration of the cellular tissue which sur- 

 rounds them, but they had not undergone 

 any actual enlargement." Dr. Snow Beck 

 removed the neurilemma, leaving only the 

 bundles of nerve fibres or nerve tubules. 

 On comparing the nerves of the gravid 

 uterus with those of the unimpregnated 

 organ, both dissections having been simi- 

 larly conducted, he found that " the size 

 of the nerves in both dissections is essentially 

 the same ; and when the nerves are carefully 

 compared, no doubt is left that the nerves of 

 the gravid uterus have undergone no change 

 in size, nor any change in position, except 

 that consequent upon the development of the 

 organ." 



But the neurilemma consists entirely of 

 fibrous tissue, such as is common to most 

 other parts of the body. It exhibits no struc- 

 tures specially nervous. Its offices, in rela- 

 tion to nerves and ganglia, are to support, 

 protect, and bind together the nerve tubules 

 and ganglionic nerve corpuscles. 



Now the real point of interest to be de- 

 termined is, whether during pregnancy the 

 innervation of the uterus is increased in any 

 degree proportionate to the augmented supply 

 of blood to the organ. But the neurilemma 

 has never been regarded as either a generator 



* The Lancet, Xo. xvii. vol. ii. 1854, p. 349. 

 Upon the subject of the nerves of the gravid uterus 

 consult also, by the same author, " The Anatomy of 

 the Nerves of the Uterus," 1841 ; " On the Nervous 

 Ganglia of the Uterus," Philosophical Transactions, 

 1841, Part ii. p. 269. ; 1842, Part ii. p. 173. ; and 

 1846, Part ii. p. 211.; "Memoirs on the Ganglia 

 and Nerves of the Uterus," 1849 ; and papers in 

 the Lancet, vol. ii. 1854. Also the following: 

 Dr. Snow Beck, Philosophical Transactions, 1846, 

 Part ii. p. 213. ; and Papers in the Lancet, vol. ii. 

 1856 ; Jobert de Lamballe, " Recherches sur la dis- 

 position des Nerfs de 1'Uterus," Comptes Rendus, 

 1841, p. 882. ; F. M. Kilian, "Die Nerven des Ute- 

 rus" ; Zeitschrift, fUr Rat. Med., Henle und Pfeufer, 

 Bd.X. 1851; M. Hirschfeld, "Note sur les Nerfs de 

 I'Ute'rus;" Gazette Me'dicale, Oct. 1852, No. 44.; 

 C. F. J. Boullard, M.D., * Quelques mots sur 1'Ute'- 

 rus," 1853. 



