964 



SPERM, OVA, AND PREGNANCY 



TABLE 16.3 



The effect of increase or decrease of body temperature and hypoxia on the pregnancy of the rat 



(From L. Fernandez-Cano, Fertil. & Steril., 9, 45, 1958.) 



Group 



Control 



High body temperature 

 High body temperature 

 High body temperature 

 High body temperature 

 Low body temperature . 

 Low body temperature . 

 Low body temperature . 

 Low body temperature . 



Hypoxia 



Hypoxia 



Hypoxia 



Hypoxia 



Days of 

 Treatment 



1-2 

 3-4 

 6-7 



10-11 

 1-2 

 3-4 

 6-7 



10-11 

 1-2 

 3-4 

 6-7 



10-11 



Total No. 

 Corpora 

 Lutea 



166 

 98 



117 

 95 

 89 

 93 

 98 



100 

 91 



103 



108 

 97 

 94 



Percentage of Degener- 

 ation 



Before 

 implan- 

 tation 



2.4 

 52 

 28 



2 



2 

 25 

 33 



3 



2.1 

 21.3 

 25.9 







2.1 



After 

 implan- 

 tation 





 12 



3 

 14 

 10 



5 



4 

 13 

 12.1 



2.9 



3.7 

 25.7 

 65.9 



Total 

 degener- 



2.4 

 64 

 31 

 16 

 12 

 30 

 37 

 16 



14.2 

 24.2 

 29.6 

 25.7 

 68.0 



Means of 

 Degenera- 

 tion for 

 Each Rat 



0.2 

 8.3 

 4.6 

 1.9 

 1.3 

 3.5 

 4.5 

 2.0 

 1.6 

 3.1 

 3.8 

 3.1 

 8.0 



Standard 

 Error 



0.11 



1.6 



2.6 



0.5 



1.8 



1.0 



1.4 



0.2 



0.5 



0.4 



0.3 



1.0 



1.4 



Percent- 

 age 

 against 

 Control 



>0.01 

 >0.01 



>0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 

 >0.01 



kind have been observed for such steroids 

 as the estrogens, gestagens, and the 17- 

 a-hydroxycorticoids. In addition, certain 

 nonsteroidal hormones such as the gonado- 

 trophins human chorionic gonadotrophin 

 (HCG) and pregnant mare's serum (PMS) 

 and the polypeptide, relaxin, increase dur- 

 ing gestation. Some evidence for a possible 

 involvement of thyroxine, prolactin, and 

 oxytocin will be included. The maximal 

 concentration of these hormones in the 

 blood of the female during pregnancy is 

 given in Table 16.4. 



A. ESTROGENS 



The fact that large amounts of estrogen 

 are excreted in the urine of pregnant women 

 and mares has been known for a long time. 

 Additional data (reviewed by Newton, 

 1939) indicate that this phenomenon occurs 

 in all species studied, such as the chimpan- 

 zee, the macaque, the cow, the pig, and 

 the rat. In general, an increasing amount 

 of estrogen is excreted as pregnancy pro- 

 gresses. The estrogenic material in the 

 urine of the pregnant woman appears 

 mostly in the form of estriol with lesser 

 amounts of estrone and estradiol (Fig. 16.3) . 

 The estriol concentration increases only 

 slightly in the urine of women for the first 

 100 to 125 days of pregnancy, but there- 

 after it increases very rapidly until parturi- 

 tion. Newton (1939) discussed the possible 



role of estrogen in pregnancy in great de- 

 tail. He first asked whether the increased 

 urinary concentration of estrogen indicates 

 that this hormone is acting to a lesser de- 

 gree as pregnancy advances or to a greater 

 degree. He marshaled his facts pro and con 

 and came to the conclusion that there is an 

 increased production of estrogen through- 

 out pregnancy and hence an increased ac- 

 tivity of the hormone. In his analysis of 

 the action of estrogen, five possibilities 

 were suggested. (1.) Estrogen is involved 

 in the growth of the uterus in pregnancy. 

 (2) Estrogen is involved in the increased 

 uterine contractility and sensitivity to 

 oxytocin necessary for parturition. (3) Es- 

 trogen is concerned with the continued se- 

 cretion of progesterone by way of the pitu- 

 itary glancl or acting directly on the corpus 

 luteum. (4) Estrogen synergizes with pro- 

 gesterone. (5) Estrogen stimulates mam- 

 mary gland growth. A 6th possibility is 

 that estrogen reverses the progesterone 

 block (Csapo, 1956a). Several of these pos- 

 sibilities will be considered later in con- 

 junction with progesterone, the mainte- 

 nance of pregnancy, and jiarturition. 



B. GESTAGENS 



The significance of the role of proges- 

 terone during pregnancy stemmed from the 

 historic work of Fraenkel who proved the 

 validity of Gustav Born's suggestion that 



