CHAPTER IV 



CHANGES IN THE OVARY— OOGENESIS— GROWTH OP FOL- 

 LICLES— OVULATION— FORMATION OF CORPORA LUTEA 

 AND ATRETIC FOLLICLES— THE SIGNIFICANCE OF THE 

 PROCESTROUS CHANGES IN THE UTERUS 



"The newest freak of the Fallopian tubes and their fimbrise, and the 

 very latest news from the ovisac and the corpora lulea." — John Beown, 

 Hor(s Svisecivce. 



Development of Ovary and Oogenesis 



The animal egg is a large spheroidal cell consisting of external 

 protoplasm or cytoplasm, a nucleus or germinal vesicle, and a 

 nucleolus or germinal spot.^ Within the cytoplasm is a mass of 

 food material or yolk (sometimes known as deutoplasm), the 

 quantity of which varies slightly in different Mammalia, and i,s 

 very considerable in birds and certain other animals. The 

 unfertihsed ovum differs from the male germ-cell or spermatozoon 

 in its devoting itself mainly to the storage of food-substance and 

 accumulation of potential energy, for it is incapable of active 

 movement. The metabolic processes of the ovum, therefore, are 

 almost entirely constructive, while those of the spermatozoon 

 are largely destructive. The function of the ovum is to con- 

 jugate with the spermatozoon, and subsequently, by a lengthy 

 process of cell division, to give rise to a new individual. 



The mammahan ovary,^ or organ in which the ova are pro- 

 duced, is composed of a stroma of fibrous connective tissue, 

 which contains some plain muscular fibres (especially in the 

 neighbourhood of the attachment to the broad ligament) as 

 well as numerous blood-vessels. The surface is hned by a 

 layer of columnar epithehal cells. Within are a number of 



' A oentrosome has been described as present in the ova of some animals. 

 For a detailed description of the ovum in different forms see Wilson, The 

 Cell in Development and Inheritance, 2nd Edition. New York, 1900. 



' See also Stratz, Der geachlechtareife Sdugethiereierstock, Haag, 1898. 



113 H 



