Abstract
It is well known that the pars anterior of the hypophysis cerebri is made up of a variety of cell types, viz., eosinophils, basophils, and chromophobes (Flesch, 1 Kraus 2 ). The presence of at least 2 functions attributable to the pars anterior is of interest in view of these cell types, and it is logical to suppose that a relation may exist between the different types and functions.
Dortzbach and Smith 3 recently have studied the effect of anterior lobes, obtained from foetal pigs, when introduced intra-muscularly into the immature mouse. They employed a graded series and found that the 10 cm. stage was the earliest at which the growth hormone was present in sufficient quantity to evoke a positive response to their test. Anterior lobe material from 20 cm. pigs produced a positive response to the maturity reaction. These results indicate the existence of a time difference in the attainment of the threshold values necessary to cause a response to the biological tests employed by these authors.
It seemed advisable to make a histological study of a graded series of foetal pig pituitaries in order to determine whether any relation exists between the physiological phenomena described by Dortzbach and Smith and the order of appearance of the cell types characteristic of the pars anterior. A graded series was obtained and the 10 and 20 cm. sizes were selected as critical stages. The entire pituitary in each instance was carefully dissected out and fixed in Zenker's fluid. All material was sectioned 5 micra in thickness and stained with eosin and Delafield's haematoxylin.
The histological picture characteristic of the 10 cm. stage was decidedly a basophilic one. A few scattered eosinophils were present but their scarcity seemed to indicate that the dominant element, at least in a morphological sense, is the basophilic cell.
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