GENERAL ZOOLOGY 



Uterine tube 



Ovary 

 Broad ligament 



Follicle 



Cervix 

 Vagina 



Fig. 5.2. Diagram of ovaries and reproductive tract in man; the 

 uterus and rie;ht Fallopian tube are shown with their walls cut away 

 to reveal their cavities, and the ostium is pulled away from the 

 ovary which is shown in section. On the left, arrows indicate the 

 path of the egg from ovary to uterus; this figure is about one-half 

 natural size. A part of a mature follicle with its egg or ovum is 

 shown in the inset. (Redrawn from G. W. Corner, Ourselves Unborn, 

 copyright 1944 by Yale University Press, printed by permission.) 



deferens) which opens into the ventral part of the cloaca in reptiles and birds 

 and into the urethra, or neck of the urinary bladder, in mammals (Fig. 5.1/4; 

 cf. Fig. 3.11, p. 57). There are three kinds of so-called accessory glands 

 which secrete constituents of the seminal fluid into the ductus deferens in 

 mammals. 



The female reproductive organs are known as ovaries (Fig. 5.15). They 

 are suspended by ovarian mesenteries, the mesovaria, ventral to the anterior 

 end of the excretory organs in vertebrates other than the mammals; a descent 

 of the ovaries into the pelvic region of the peritoneal cavity occurs in mam- 

 mals (see Fig. 4.8, p. 94). Ovaries may be sac-like, as they are in the frog, 

 or solid, as they are in higher vertebrates (Figs. 5.2 and 5.4.4). The wall of 

 an ovary of the frog and the outer layer of an ovary of a mammal are com- 

 posed, for the most part, of relatively undifferentiated germ cells, each sur- 

 rounded by an envelope of cells, the follicle (Fig. 5.35 and p. 122). In those 

 vertebrates in which the oocyte stores a large amount of food material, the 

 follicle consists of only two or three layers of cells and becomes very incon- 

 spicuous as the growth of the oocyte is completed. Contrasted with such a 

 condition is the great growth of the follicle in mammals in which little food 

 is stored in the oocyte. The mammalian follicle becomes vesicular, and its 

 cavity is filled with follicular fluid. 



The reproductive ducts of the female are the oviducts, which are not di- 

 rectly continuous with the ovaries but open into the coelomic cavity. The 

 ostium, or opening of the oviduct, is located in the anterior end of the 

 coelom in the frog but lies nearer the ovary in higher vertebrates. In many 



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