CHAPTER XXVII. 

 REPRODUCTION. 



Reproduction is the process by which a new individual is initiated 

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

 Reproduction is the result of the union and subsequent development 

 of germ- and sperm-cells. These cells are produced and their union 

 accomplished by the cooperation of the reproductive organs charac- 

 teristic of the two sexes. 



Embryology is a department 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 ORGANS OF THE FEMALE. 



The reproductive organs of the female comprise the ovaries. 

 Fallopian tubes, uterus, and vagina (Fig. 317). 



The Ovaries. The ovaries 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 toward its peripheral portions. 

 It is estimated that the human ovary contains from 20,000 to 40,000 

 follicles. The follicles vary considerably in size ; while many are visible 

 to the unaided eye, others require for their detection high powers 

 of the microscope. Although the follicles are present in the ovary 

 at the time of birth, it is not until the period of puberty that they 

 assume functional activity. 



From this time on to the catamenial period there is a constant 

 growth and development of these follicles. Each follicle consists of 

 an external investment of fibrous tissue and blood-vessels, and an 

 internal investment of cells, the membrana granulosa. At the lower 

 portion of this membrane there is an accumulation of cells, the pro- 



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