OVUM. 819 



bloodvessels; and an internal coat, named ovi-capsule, which is lined by a layer 

 of nucleated cells, called the membrana granulosa. The fluid contained in the 

 interior of the vesicles is transparent and albuminous, and in it is suspended 

 the ovum. 



The formation, development, and maturation of the Graafian vesicles and 

 ova continue uninterruptedly from infancy to the end of the fruitful period of 

 woman's life. Before puberty, the ovaries are small, the Graafian vesicles con- 

 tained in them minute, and few in number; and few, probably, ever attain full 

 development, but shrink and disappear, their ova being incapable of impregna- 

 tion. At puberty, the ovaries enlarge, are more vascular, the Graafian vesicles 

 are developed in greater abundance, and their ova capable of fecundation. 



Discharge of the Ovum. The Graafian vesicles, after gradually approaching 

 the surface of the ovary, burst; the ovum and fluid contents of the vesicles are 

 liberated, and escape on the exterior of the ovary, passing from thence into the 

 Fallopian tube, the fimbriated processes of which are supposed to grasp the 

 ovary, the aperture of the tube being applied to the part corresponding to the 

 matured and bursting vesicle. In the human subject and most mammalia, the 

 maturation and discharge of the ova occur at regular periods only, and are 

 indicated, in the mammalia, by the phenomena of heat or rut; and in the human 

 female, by menstruation. Sexual desire is more intense in females at this pe- 

 riod; and if the union of the sexes takes place, the ovum may be fecundated. 



Corpus Luteum. Immediately after the rupture of a Graafian vesicle, and 

 the escape of its ovum, the vesicle is filled with blood-tinged fluid; and in a 

 short time the circumference of the vesicle is occupied by a firm, yellow sub- 

 stance, which is probably formed from plasma exuded from its walls. Dr. Lee 

 believes that this yellow matter is deposited outside both the membranes of the 

 follicle; Montgomery regards it as placed between the layers; while Kolliker 

 considers it as a thickening of the inner layer of the outer coat of the follicle. 

 The exudation is at first of a dark brown or brownish-red color, but it soon 

 becomes paler, and its consistence more dense. 



For every follicle in the ovary from which an ovum is discharged, a corpus 

 luteurn will be found. But the characters it exhibits, and the changes produced 

 in it, will be determined by the circumstance of the ovum being impregnated 

 or not. 



Although there is little doubt that corpora lutea exist in the ovaries after the 

 escape of ova, independent of coitus or impregnation, it appears that the corpus 

 luteum of pregnancy (true corpus luteum) possesses characters by which it may 

 be distinguished from one formed in a follicle, from which an ovum has been 

 discharged without subsequent impregnation (false corpus luteum). 



The true corpora lulea are of large size, often as large as a mulberry; of a 

 rounded form, and project from the surface of the ovary, the summit of the 

 projection presenting a triangular depression or cicatrix, where the peritoneum 

 appears to have been torn. They contain a small cavity in their centre during 

 the early period of their formation, which becomes contracted, and exhibits a 

 stellate cicatrix during the latter stages of pregnancy. Their vascularity, 

 lobulated or puckered appearance, firm consistence, and yellow color, are also 

 characteristic marks of true corpora lutea. 



False corpora lutea are of small size, do not project from the surface of the 

 ovary, are angular in form, seldom present any cicatrix, contain no cavity in 

 their centre; the material composing them is not lobulated, its consistence is 

 usually soft, often resembling coagulated blood; the yellow matter exists in the 

 form of a very thin layer, or more commonly is entirely wanting. False 

 corpora lutea most frequently result from the effusion into the cavities of the 

 Graafian vesicles of serum or blood, which subsequently undergoes various 

 changes, and is ultimately removed. Dr. Lee states, that in the false corpora 

 lutea the yellow substance is contained within, or attached to, the inner surface 



