CHAPTER XXXI 



REPRODUCTION 



Reproduction is the process by which a new individual is initiated and 

 developed and the species to which it belongs is preserved. Reproduc- 

 tion is the result of the union and subsequent development of germ-* and 

 sperm-ceUs. These cells are produced and their union accomplished by the 

 cooperation of the reproduc- 

 tive organs characteristic of 

 the two sexes. 



Embryology is a depart- 

 ment of anatomic science 

 which has for its object the 

 investigation of the successive 

 stages that the new being 

 passes through during its 

 gradual development prior to 

 birth. 



THE REPRODUCTIVE OR- 

 GANS OF THE FEMALE 



The reproductive organs of 

 the female comprise the ova- 

 ries, Fallopian tubes, uterus, 

 and vagina. 



The Ovaries. The ova- 

 ries are two small, flattened 

 bodies, measuring about 40 

 mm. in length and 20 in 

 breadth. They are situated 

 in the cavity of the pelvis, one 

 on either side, and embedded 

 in a fold of the peritoneum, 

 known as the broad ligament. 

 A section of the ovary shows 

 that it consists externally of a 

 thin, firm, connective-tissue 

 membrane and internally of a fine connective-tissue stroma, supporting 

 blood-vessels, non-striated muscle- fibers and nerves, and containing in its 

 meshes a very large number of spheric sacs named after their discoverer, de 

 Graaf, the Graafian sacs or follicles. These follicles are very numerous and 

 are present in all portions of the ovary, though they are most abundant to- 

 ward its peripheral portions. It is estimated that each human ovary con- 

 tains from 20,000 to 40,000 follicles. The follicles vary considerably in size; 



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FIG. 323. SECTION OF CORTEX OF CAT'S OVARY, 

 EXHIBITING LARGE GRAAFIAN FOLLICLES. an^er- 

 ipheral zone of condensed stroma. b. Groups of im- 

 mature follicles, c. Theca of follicle, d. Membrana 

 granulosa. e. Discus proligerus. /. Zona pellucida. 



f. Vitellus. h. Germinal vesicle, i. Germinal spot. 

 . Cavity of liquor folliculi. (After Piersol.} 



