68 Proceedings of the Royal Irish A cademy. 



the fibrous theca externa, or external tunic. Directly ovulation has taken 

 place, the follicle epithelial cells (or membrana granulosa) begin to grow and 

 develop in a remarkable manner, and form large polygonal glandular cells 

 coutainins the so-called lutein gi-anules, -which in nearly all mammals give 

 the corpus luteum a yellow or reddish brick colour. The theca interna cells 

 are assisted in the process of organization of these gland cells by the invasion 

 of larue iiioi'owths from the theca externa : the latter carries big blood- 

 vessels and lymph channels (PI. Ill, fig. 3). The luteal cells are almost, if not 

 entirely, folUcle-epithelial in origin — but in the human and, in all probability, 

 in some of the lower mammals certain of the theca interna cells are said to 

 become very much like the glandular, true luteal cells in appearance. These 

 are called para-lutein cells. The coi-pus luteum goes on developing till it is a 

 large structure protruding on the surface of the ovary (PI. Ill, fig. 1, lower 

 figurei. 



Two kinds of corpora lutea are recognized — a corpus luteum spurium, 

 corpus luteum of ovulation, or menstrual corpus luteum, and what is often 

 called a corpus luteum verum, or corpus luteum of pregnancy. According 

 to some observei-s there are certain marked diflferences between the two 

 kinds, even in the earlier stages of formation of these bodies, but for the 

 lower mammals ilarshall and many other authorities believe that up to a 

 late stage there is no difference beyond size between the two types. This is 

 also my ^iew. The human corpus luteum of menstruation is certainly 

 formed completely so far as the histological arrangements of its elements 

 are concerned. In PL III, fig 1, is a section of the corpus luteum of ovulation, 

 showing at ct a medullary wedge of connective tissue, which becomes 

 organized within the remains of the old antrum foUieuli. (Part of this 

 wedge is photographed on PI. T, fig. t<. riix). At cc, is an open space occupied 

 by a coagulable fluid into which, especially from the area x, large numbers 

 of leucocytes fPl. V, fig. 10, h) and fibroblasts (./) are wandering. 



If pregnancy supervenes the cor-pus luteum grows larger and by the 

 fourth or fifth month is the size of a pigeon's egg. Some time before 

 parturition, the corpus luteum begins to undergo regression changes, 

 ultimately forming a scar-Uke structure, as does the corpus luteum spurium 

 (fig, 1, ca). 



According to Yillemin. the human menstrual coi-pus luteum develops for 

 eight to ten days after ovulation, and this is followed by a " periode d'etat," 

 or period during which neither further development nor regression takes place, 

 lasting five or six days, after which regression sets in. 



With this short preliminary sketch we may undertake an examination of 

 the modern literature bearing on otu- problem. 



