ESTROGEN AND PROGESTERONE 



the keratinized cells of the lesion become 

 vacuolated and are lost. 



In contrast with the effects of estrogen 

 on the cervix, the modifications that occur 

 as pregnancy advances are remarkable. The 

 cervix becomes a soft thin-walled structure, 

 the glands increase in number, and their 

 lumina become greatly enlarged, pressing 

 the stroma into thin partitions between 

 them, and the amount of mucus secreted is 

 enormous (Fig. 9.19). Attempts at duplicat- 

 ing these changes in castrated animals by 

 hormone therapy have been only partially 

 successful. Estrogen produces a solid thick- 

 walled cervix that tends to be larger than 

 normal, an effect that is especially notice- 

 able in young animals. Progesterone does 

 not promote cervical growth and repair of 

 the glands unless large doses are given and 

 even then there is little if any secretion. The 

 best results were obtained when both estro- 

 gen and progesterone were given and espe- 

 cially so when relaxin was added to the 

 treatment (see chapter by Zarrow). 



VII. The Vagina 



The general features of the vaginal smear 

 of rhesus monkeys have been described by 

 several investigators (Allen, 1927; Hart- 

 man, 1932; Westman, 1932) and a detailed 

 study of the cellular components at differ- 

 ent times of the menstrual cycle has been 

 made by Lopez Columbo de Allende, Shorr 

 and Hartman (1945). The changes in the 

 vagina of a monkey are in most respects like 

 those found for the human being (Papa- 

 nicolaou, Traut and Marchetti, 1948; Lopez 

 Columbo de Allende and Orias, 1950). Epi- 

 thelial growth and desquamation of corni- 

 fied cells continue at all stages of the cycle 

 but at various rates. The epithelium is 

 thinnest at menstruation and gradually in- 

 creases in thickness during the follicular 

 phase, reaching a maximum at ovulation. 

 At this time there is a well developed basal 

 area in which numerous mitoses can be seen 

 and from which many papillae or ''bulbs" 

 extend into the underlying stroma. Above 

 this is an intermediate zone, an interepithe- 

 lial zone of cornification (so called Dierk's 

 layer), and a heavily cornified outer zone 

 (Fig. 9.21). 



Cellular proliferation is less rapid during 

 the luteal phase and apparently cells are 



desquamated more rapidly than they are re- 

 placed. Consequently there is a decrease in 

 the thickness of the epithelium in the luteal 

 phase which may include an almost com- 

 plete loss of the cornified zone (Davis and 

 Hartman, 1935). The effects are probably 

 due to progesterone because similar changes 

 are seen following the introduction of pro- 

 gesterone into a treatment in which estrogen 

 is being given. 



The vaginal epithelium of a castrated 

 monkey is remarkably sensitive to estrogen. 

 A small daily dose of 5 to 10 /xg. estradiol 

 will stimulate growth of an atrophic epi- 

 thelium of 4 to 8 cells in thickness to one of 

 60 or even 80 layers thick within 3 weeks. 

 One of the first things that is noticed as the 

 vaginal epithelium thickens is the numerous 

 mitotic figures in the stratum germinativum 

 followed by a marked increase in the num- 

 ber of epithelial papillae along the base- 

 ment membrane. This condition of rapid 

 growth, cornification, and loss of cells into 

 the vaginal lumen is typical of the follicular 

 phase of the menstrual cycle and can be 

 maintained indefinitely. 



l''i(.. U.21. Tlie vaginal epithelium of a castuUMJ 

 monkej' showing growth antl cornification induced 

 by estrogen. 



