^90 



SPERM, OVA, AND PREGNANCY 



fall in hematocrit occurs concomitantly with 

 the fall in the two blood constituents along 

 with an increase in the reticulocytes. The 

 time of onset of the increase in reticulocytes 

 is variable and seems to occur during the 

 second trimester of gestation. Their number 

 returns to normal before parturition in spite 

 of the increasing severity of the anemia. A 

 second rise in the reticulocytes is seen dur- 

 ing the first week postpartum. All the other 

 constituents return to normal values during 

 the first or second week postpartum. 



Disagreement exists as to whether there 

 is a change in the volume of the extracellular 

 fluid compartment during pregnancy in the 

 human being. Whereas certain investigators 

 have reported rather marked increases in 

 the extracellular space (Chesley and Ches- 

 ley, 1941; Chesley, 1943; Freis and Kenny, 

 1948; Caton, Roby, Reid and Gibson, 1949; 

 Friedman, Goodfriend, Berlin and Gold- 

 stein, 1951; Jarosova and Damn, 1951), 

 others have reported that the changes in 

 this fluid compartment are proportional to 

 changes in the body weight (Lambiotte- 

 Escofiier, Moore and Taylor, 1953; Seitchik 

 and Alper, 1954). The results obtained in 

 the rabbit support the findings of the latter 

 authors as no disproportionate increase in 

 the thiocyanate space was observed during 

 pregnancy in the rabbit. The slight increase 

 that occurred during the last trimester of 



ESTHAOIOL TREATMENT 



DAYS OF TREATMENT 



Fig. 16.24. Changes in blood plasma and total 

 erythrocyte volume in the ovariectomized rabbit 

 treated with 1 mg. estradiol daily. (From L. M. 

 Horger and M. X. Zarrow, Am. J. Physiol., 189, 

 407, 1957.) 



DAYS ANTE PARTUM 



Fig. 16.25. Changes in the blood plasma and 

 total erythrocyte volume during pregnancy. 

 (From L. M. Horger and M. X. Zarrow, Am. J. 

 Physiol., 189, 407, 1957.) 



gestation was in good agreement with the 

 fluid accumulation by the developing fetus. 

 Similarly the increase in blood volume in 

 the rat is correlated with increase in body 

 weight. 



Thus the anemia of pregnancy as ob- 

 served in the rabbit and rat is very similar 

 to that reported for man. It can be charac- 

 terized as a normochromic and normocytic 

 anemia. Although a decrease in the relative 

 concentrations of hemoglobin and erythro- 

 cytes occurs, the total amounts of these 

 components of the blood remain unchanged. 

 Consequently, the anemia of pregnancy is 

 due to a hemodilution. 



The anemia induced by treatment with 

 estradiol is similar to the anemia of preg- 

 nancy in many respects. Witten and Brad- 

 bury (1951) treated 16 women with 5 mg. 

 estrone or 0.4 mg. estradiol dipropionate 

 and noted an erythrocyte drop of 14.8 per 

 cent, a hemoglobin drop of 8.5 per cent, a 

 hematocrit drop of 15 per cent, and a blood 

 volume increase. Treatment of the castrated 

 rabbit with 1 mg. estradiol daily caused a 

 20 per cent decrease in both erythrocyte 

 count and hemoglobin with no significant 

 changes in total hemoglobin or number of 

 erythrocytes. Estradiol also caused an in- 

 crease in plasma and blood volume (Fig. 

 16.24) which was comparable to that seen 

 during pregnancy (Fig. 16.25), but no sig- 



