REPRODUCTION 



73 



periodic leukocytosis so marked in the rest of the genital tract. Cyclical 

 changes in certain non-ciliated cells in the epithelium of the ampulla have 

 been both described and denied (2, 3, 48, no). These cells protrude into 

 the lumen of the tube in an unusual fashion, and there is some evidence that 

 the protrusion shows cyclic changes. For some hours following ovul- 

 ation the upper part of the oviduct is distended with fluid. 



D P EMIM2 D P EMIM2 



Fig. 3q. — Graph showing various cyclic phenomena which accompany the estrous 

 cycle. The curves have been adjusted to make corresponding points of the cycle cor- 

 respond as nearly as possible. D = diestrus, P = proestrus, E = estrus, Mi = metes- 

 trus-i, M2 = metestrus-2. 



The ovary. — Cyclic changes are pronounced in the ovary (Fig. 39 and 

 Tables 4 and 5). A conspicuous feature is the rapid growth of a few of the 

 follicles prior to ovulation. Lane and Davis (79) sectioned the ovaries of 

 twenty rats, five in each of the four major divisions of the estrous cycle, and 

 classified the follicles according to diameter. The results are shown in 

 Table 5. It will be seen that by proestrus the follicles that will ovulate at 

 estrus are fairly definitely set apart by their larger size. Brambell and 



