372 MR T. ARTHUR HELME ON HISTOLOGICAL OBSERVATIONS ON 



(a) Character of Change. It is evident that no such fatty degeneration as has been described 

 by Kilian really occurs in the uterus undergoing the normal involution. I have been unable to find 

 one single muscle cell whose substance gave the characteristic appearances or reactions of fat. 



On the other hand, the muscle cells do undergo a change ; but this change, though retrogressive, 

 partakes more of the characters of an atrophy than a degeneration, the cell substance becoming 

 .slightly dimmer and more granular, and progressively diminishing in amount. But it must be 

 pointed out that this physiological retrogression differs totally from a pathological atrophy — in the 

 latter it is the specific elements of a tissue that diminish and disappear, while the connective tissue 

 Framework is not affected, or, if affected, it is in the way of increase and not of decrease, e.g., in the 

 atrophy of muscle following destruction of its nerve supply there is found a diminution of the 

 muscle cell substance, while the connective tissue shows an increase. On the other hand, in the 

 physiological retrogression of the involving uterus, there is no increase of connective tissue, but an 

 actual destruction and disappearance of it; while, so far as the muscle is concerned, merely a diminu- 

 tion of the volume of its individual cells. The term granular atrophy would mislead, as suggesting 

 an increase of connective tissue, and I prefer not to use it. The change is, therefore, one of physio- 

 logical retrogression : the actual chemical character is not revealed by the microscope, but it is 

 probable that the cell protoplasm undergoes a sort of peptonisation — all the surplus material that is 

 no longer required being changed into some more soluble substance, which finds its way into the 

 surrounding lymph — but, whatever its chemical nature, it is certainly not fatty, no traces of fat 

 being found in the muscle cells, intercellular substance, or lymph spaces. 



(b) Time. As already described, when dealing with the muscle cells during pregnancy, towards 

 full time the muscle fibres become greatly swollen and distended-looking, with a remarkably clear 

 translucent or glassy appearance, evidently what is described as hyaline, while in many fibres spots 

 which look like " vacuoles " have appeared, resembling the so-called serous degeneration. Now, 

 within the first 24 hours of the puerperium, a tremendous change is wrought in these fibres, their 

 size has been greatly diminished, and many of the fibres have already lost that clear glassy look, and 

 instead present a dim or hazy, though still hyaline or translucent, refractile aspect (somewhat like 

 ground-glass or spermaceti). Other fibres (especially in the vascular layer between the two muscular 

 coats), greatly reduced in volume, still present the clear hyaline or glassy appearance of pregnancy, 

 but by the second day all the fibres present the dim hyaline aspect ; and from this time onwards 

 the diminution advances progressively and equally in all fibres alike till the 10th day, when it 

 has reached its greatest height. There are evidently two stages in this post-partum change : — 

 (1) An exceedingly rapid and remarkable alteration in appearance within the first 36 hours, i.e., 

 a change from the clear hyaline to the dim hyaline appearance, accompanied by a rapid diminution 

 in volume. (2) A gradual and progressive diminution in the volume of the dim hyaline fibres up to 

 the 10th day. 



(c) Position. The diminution of volume occurs simultaneously in all fibres in all parts of the 

 uterus ; it does not commence at one edge and advance, inwards or outwards, nor does it go on more 

 rapidly at the inner or outer edge, but commences at the same time, and proceeds at the same rate 

 in all the fibres throughout the organ. 



In the uterus 24 hours post partum one finds many fibres which have not yet lost their clear 

 glassy appearance, and these especially around the vascular layer which separates the circular from 

 the longitudinal muscular coat. 



All fibres, however, both clear and dim, are diminished in size. After 36 hours all the fibres 

 present the same appearance, and henceforward undergo a parallel process of change, so that in a 

 given uterus one finds each fibre in a condition similar to that of its neighbours. One does not find 

 a group of degenerating cells lying by the side of a group of healthy cells, and another group of 

 completely degenerated or young developing cells. 



(d) Amount of Diminution. Kilian,* in speaking of the rabbit's uterus, says- — " The involution, 

 however, is not of the nature thought by obstetricians, but a complete atrophy, dissolving 



* " Die Structur des Uterus bei Thieren," von Dr F. M. Kiuan, Zeit.f. ration. Med., ix. Bd. 1 Hf't., 1849. 



