HISTOPHYSIOLOGICAL STUDIES ON THE CORPUS ALLATUM OF LEUCOPHAEA MADERAE. III. THE EFFECT OF CASTRATION ,

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Abstract
Compared with the periodic structural changes of the corpora allata in the course of normal reproductive cycles, the morphological characteristics of those of castrate females are more impressive and less predictable. A small proportion of ovariectomized animals have abnormally large corpora allata, and these are confined to an intermediate period of the adult life span. This suggests that their growth response lacks permanency. The apparent cause of the overgrowth is the persistent absence of feedback stimuli from the ovaries. The rise in relative and absolute cyto- plasmic content with increasing organ size, observed previously in normal animals, applies equally to gonadectomized females whose corpora allata do not exceed the maximum of the control values. Above this level, the growth pattern differs in that no further drastic change in nuclear-cytoplasmic ratio occurs, i.e., nuclear numbers and cyto-plasmic content increase at the same rate. Compared to those of normal controls, the corpora allata of castrate females contain progressively increasing amounts of saliva-resistant PAS-positive granules, probably glycoprotein in nature. A conspicuous accumulation of comparable cytoplasmic inclusions also occurs in various other tissues, such as the fat body, musculature, and nervous system. The parallelism in their frequency suggests a common denominator. Whether they accumulate because of the absence of an ovarian hormone, or merely in response to metabolic changes following castration, is as yet undetermined. In contrast to females, male castrates do not differ significantly from normal controls as to the volume and cytoplasmic content of their corpora allata. The same applies to the presence of PAS-positive material in various tissues. This difference between the sexes in response to castration is undoubtedly related to the absence of a corpus allatum-gonad axis in males.