Abstract
Many investigators have demonstrated that injections of pregnancy urine or human placental extracts into immature (21-day or above) female rats result in an increase in the size of the ovaries due to follicular maturation and corpus luteum formation. However, subsequent studies of Selye and Collip 1 have revealed that injection of such extracts into infantile female rats (6 to 8 days) fails to cause follicular maturation and development of corpora lutea, but does result in a marked increase in the size of the thecal cells giving rise to thecal corpora lutea.
Collip and associates 2 have found that injection of placental extracts increases the size of the pituitaries of immature female rats (21 days or above) as well as the ovaries. We have confirmed these results, using both extracts of human placentae and pregnancy urine.† 3 - 5 Histologically, the pituitaries of these rats exhibited a marked granular loss from the basophiles and a less evident loss of granules from the eosinophiles. Cell counts revealed that the percentages of the basophiles and eosinophiles were decreased, while that of the chromophobes was increased. Since it has been found that injection of pregnancy urine extract brings about a markedly different ovarian effect in infantile rats (6 to 8 days) it seemed of interest to study the anterior pituitaries of such rats.
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