Aug. 3, 1876] 



NATURE 



287 



TURNER ON THE PLACENTA 



Lectures on the Comparative Anatomy of the Placenta. 

 First Series. By Wm. Turner, M.B, Lond. Pp. 122, 

 Woodcuts, and Three Coloured Plates. (Edinburgh : 

 A. and C. Black, 1876.) 



THE anatomy of the Placenta has been studied by the 

 best anatomists from Fabricius and Harvey to 

 Hunter, Von Baer, and Sharpey ; but much remained to 

 be done when Prof. Turner took up the investigation; and 

 those who are acquainted with his admirable memoirs, 

 which lie hidden in the Transactions of the Royal Society 

 of Edinburgh, know how much he has done to correct 

 and extend our knowledge. The present volume con- 

 tains a series of lectures delivered before the Royal 

 College of Surgeons last year, and illustrated by speci- 

 mens from their magnificent Hunterian museum, as well 

 as from that of the University of Edinburgh. Prof. Turner 

 has also been liberally aided by Dr. Sharpey, Mr. Huxley, 

 and other anatomists with material, so that he is able not 

 only to compare the placenta in man with that in the cat, 

 bitch, cow, sheep, and mare, but also in the hyrax, 

 elephant, seal, giraffe, alpaca, lemur, sloth, grampus, and 

 narwhal. The present volume deals only with the diffuse, 

 cotyledonous, and zonary forms of placenta ; a second 

 series of lectures will complete the subject by a similar 

 discussion of the discoid placenta, and we shall then 

 have the most complete monograph on this important 

 structure which has yet appeared. 



Prof. Turner begins with a short introductory account 

 of the mucous membrane of the unimpregnated uterus, 

 and especially of its glands, and of the chorion and other 

 foetal membranes. In describing the amnion, he gives 

 the best account yet published of the curious brown or 

 yellow appendages of this membrane found in various 

 forms and in different species by Bernard, Owen, RoUes- 

 ton, and others, which are probably identical with the 

 " hippomanes " of veterinary surgeons. 



The structure of the diffuse placenta in Stis^ Eqmis, 

 Orca, and other genera is then described. The villi of 

 the chorion do not fit into the orifices of uterine glands, 

 but into inter-glandular crypts, which do not exist in the 

 unimpregnated uterus, and only appear as gestation ad- 

 vances. In Cetacea, as in the pig and mare, the villi do 

 not persist over the whole chorion, but die off from the 

 two poles, having only a certain amount of vascular tissue 

 to represent the mesoblast of the allantois. Bui in the 

 mare and the grampus there is also a third bare spot 

 which corresponds with the os uteri, and is unrepresented 

 in the pig. In the latter there are numerous bare spots 

 scattered over the chorion, which were described by Von 

 Baer and are now found by the author to correspond to 

 parts of the uterine mucosa without crypts, and sparingly 

 supplied with vessels. Dr. Turner has had the oppor- 

 tunity of dissecting two pregnant Lemurs [Propithecus 

 diadcma and Lemur ru/ipes), and finds that the form of 

 the placenta in the former species is what M. Alphonse 

 Milne-Edwards described as bell-shaped {placenta en 

 cloche), i.e. the villi cover the whole chorion except at 

 the OS uteri ; but in the Red-footed Lemur there are two 

 other bare spaces at the poles of the ovum, so that the 

 placenta en cloche is a mere generic, or accidental, 

 variety of the diffuse form. Moreover, the villi came 



away from the crypts of the uterine mucosa in which they 

 lay, without taking any maternal tissue with them. Thus 

 the placenta of lemurs is neither discoid nor deciduate, 

 and one more link of connection between this group and 

 the true Primates is broken. 



In his account of the placenta of the cow. Dr. Turner 

 confirms the description by Von Baer and Weber, of the 

 small pouches scattered over the chorion between the 

 cotyledons, and is disposed to agree with the latter ana- 

 tomist that they serve as receptacles for the secretion of 

 the uterine glands during pregnancy. Similar " pocket- 

 hke " depressions were discovered by the author in the 

 giraffe's placenta which was described by Owen in 1842. 

 In this animal, as in the red deer, the cotyledons are 

 arranged in longitudinal rows, and between them are not 

 only much smaller tufts, but also short club-shaped villi, 

 scattered separately or in minute groups over the chorion, 

 which thus approximates to the diffuse form found in the 

 camels and the chevrotains. 



In the account of the deciduate placenta, the most im- 

 portant fact established by Prof. Turner is that there are 

 several degrees in the amount of maternal tissue which is 

 detached in parturition. If the ovum is stripped off the 

 pregnant uterus of a cat, it carries with it the whole of 

 the mucosa (decidua serotina) with which the chorion is 

 in contact ; but on careful examination of the placenta 

 after its natural detachment at birth, it is found that a 

 considerable amount of the vascular corium has been 

 left behind, and that only the superficial part with the epi- 

 thelial layer has come away with the chorion. In the bitch, 

 as was pointed out by Prof. RoUeston in 1 863, the pla- 

 centa is still less " deciduate," for there is not enough 

 mucosa detached with the ovum to form a continuous layer 

 on the uterine surface of the placenta. Dr. Turner found 

 that the placenta of a vixen agreed precisely with that of 

 the bitch in this respect ; the foldings of the uterine 

 mucosa were so minute as to produce a reticulated struc- 

 ture of the placenta, and a similar arrangement was dis- 

 covered in a specimen from Halichoerus gryphus, A 

 re- examination of the placenta of the hyrax described by 

 Prof. Huxley confirms his account of it, and contradicts 

 the assertion of two French anatomists that it is non- 

 deciduate. The poles of the chorion in the Carnivora 

 are often well-supplied with blood-vessels, though no 

 trace of villi can be found at full term beyond the equa- 

 torial region. In the otter and the weasel bare gaps 

 occur in the placental zone, as described by Bischoff in 

 1865. 



The most important points established by Prof. Turner 

 seem to be the following : — 



1. That the uterine glands are all compound and tubular, 

 and cannot be divided into two groups, as they were by 

 Sharpey, confirmed by most German anatomists. In this 

 Dr. Turner agrees with Prof. Ercolani, of Bologna. 



2. That the uterine glands do not open into the funnel- 

 shaped crypts which receive the foetal villi, but on the 

 surface between them, and that the crypts are only deve- 

 loped during the progress of gestation. Here also the 

 observations of Ercolani and of Eschricht are supported. 



3. That the deciduate character is one of degree. The 

 detached diffuse placenta consists entirely of foetal struc- 

 tures ; in the sheep and cow a large amount of maternal 

 epithelium lining the walls of the uterine crypts comes oflf 



