894 ^ MANUAL OF ANATOMY 



contain as many as 70,000 of these follicles. In follicles a little 

 more advanced the investing epithelium becomes columnar, and 

 is arranged in two layers — outer and inner, the latter surrounding 

 the ovum. In more mature follicles fluid, called the liquor folliculi, 

 accumulates between the outer and inner cellular layers, except 

 at the point where the ovum lies. The outer layer is then known 

 as the membrana granulosa, and the inner as the discus proligerus. 

 The cells of these two layers become continuous at the part where 

 the liquor folliculi is absent, so that in this manner the ovum is 

 anchored to one point of the wall of the follicle. In the most 

 mature follicles the liquor folliculi has increased in amount, and 

 the cells of the membrana granulosa and discus proligerus have 

 multiplied so as to form several strata. Each of these follicles 

 has a distinct wall, called the theca folliculi, which is formed by a 

 condensation of the surrounding stroma, and in which two layers 

 can be recognised — ^an outer fibrous and an inner vascular. There 

 is usually only one ovum in each follicle. 



Structure of the Ovum. — The ovum is a spherical cell, having a 

 diameter of about Ykr inch. It has two membranes — an external, 

 called the zona radiata (zona pellucida), and an internal, called the 

 vitelline membrane, the latter representing the cell-wall. Within 

 this is the cell-body, called the yolk, or vitellus, which contains a 

 nucleus, known as the germinal vesicle, and that in turn contains 

 a nucleolus, called the germinal spot. The zona radiata is fairly 

 thick, and is perforated by pores or canals, arranged in a radiating 

 manner, hence the name ' radiata.' These canals serve for the 

 passage of nutritive material, and also for spermatozoa preparatory 

 to impregnation. The vitelline membrane is merely a condensa- 

 tion of the yolk at the surface. The yolk, or vitellus, is semifluid, 

 very refracting, and contains many yolk granules, which are fatty 

 and albuminoid in their nature. These granules form the nutritive 

 yolk, or deutoplasm, the remainder of the yolk being called the 

 formative yolk, or cytoplasm. The nucleus or germinal vessel is 

 about 5^^^ inch in diameter. It is eccentric in position in the 

 cytoplasm, and has the usual characters of a cell-nucleus. The 

 nucleolus, or germinal spot, is granular in character. 



Blood-supply of the Ovary. — The ovary receives its blood from the 

 ovarian artery. 



Nerves. — ^These come from the ovarian sympathetic plexus, which 

 derives its fibres from the renal and aortic plexuses, and accom- 

 panies the ovarian artery. 



Lymphatics. — The lymphatic vessels of the ovary accompany 

 the ovarian bloodvessels, and terminate, for the most part, in the 

 laieral aortic glands, on either side. A few, however, terminate in 

 the pre-aortic glands. They are joined by most of the lymphatics 

 of the body of the uterus and by those of the Fallopian tube. 



The ovaries represent the testes in the male, and they have been 

 called the testes muliebres. 



