178 TRANSPORTATION OF THE GAMETES 



F. Transportation of the egg from the ovary to the site of fertilization 



1. Definitions 



2. Transportation of the egg in those forms where fertilization occurs in the anterior 



portion of the oviduct 



a. Birds 



b. Mammals 



3. Transportation of the egg in those species where fertilization is effected in the 

 caudal portion of the oviduct or in the external medium 



a. Frog 



b. Other amphibia 



c. Fishes 



G. Summary of the characteristics of various mature chordate eggs together with the 

 site of fertilization and place of sperm entrance into the egg 



A. Introduction 



1. Activities of the Male and Female Gametes in Their 

 Migration to the Site of Fertilization 



The first step in the actual process of fertiHzation and the reproduction of 

 a new individual is the transportation of the mature gametes from the place 

 of their development in the reproductive structures to the area or site where 

 conditions are optimum for their union (fig. 98). This transport is dependent 

 upon the development of the proper reproductive conditions in the male and 

 the female parent — a state governed by sex hormones. That is to say, the 

 sex hormones regulate the behavior of the parents and the reproductive ducts 

 in such a way that the reproductive act is possible. 



The transport of the female gamete to the site of fertilization is a passive 

 one, effected by the behavior of the reproductive structures. Also, the trans- 

 portation of the sperm within the confines of the male tract largely is a passive 

 affair. However, outside of the male reproductive tract, sperm motility is a 

 factor in eflfecting the contact of the sperm with the egg. Not only is sperm 

 motility a factor in the external watery medium of those species accustomed 

 to external fertilization, but also to some degree within the female genital 

 tract in those species utilizing internal fertilization. However, in the latter 

 case, sperm transport is aided greatly by the activities of the female genital tract. 



B. Transportation of the Sperm Within the Male Accessory 

 Reproductive Structures 



1. Transportation of Sperm from the Testis to the 



External Orifice of the Genital Duct in 



THE Mammal 



Sperm transport within the male genital tract of the mammal is a slow 

 process. It might be defined better by saying that it is efficiently slow, for the 

 ripening process of the sperm described in the previous chapter is dependent 



