The hypophysis of the guinea pig

The guinea pig was used as the object of this study because it is readily obtainable and also because though thousands are used yearly for experimental purposes, this animal has been neglected from an anatomical standpoint.The only reference found to the anatomy of the hypophysis of the guinea pig, was one by Oppel ('14) who referred in a few lines to its general relations and another by Paulesco ('08) who quotes Fischera in regard to the weight of the gland.The general relations of the hypophysis of the guinea pig are very similar to those existing in other vertebrates and its microscopic structure is quite similar.The most striking difference found was the presence of cilia in the cleft and also in the epithelial cysts or vesicles of the glandular portion.According to Trautman ('09), ciliated epithelium has been reported in the vesicles in the hypophysis of man and the rabbit, but Trautman was unable to find any in the cysts of any of the domestic animals studied by him.These included the horse, ass, cow, calf, sheep, goat, hog, dog and cat, and although he could not be certain Trautman thought he saw ciliated epithelium in the lining of some portions of the cleft of the pituitary of the hog.I n the guinea pig this ciliated epithelial lining of both the cleft and the vesicles was found uniformly present somewhere in all the specimens examined, but it was not present in all cysts nor did it completely line the clefts.Within the latter, in fact, it did not appear at all on the side adjacent to the pars intermedia and only on portions of the opposite side.These portions are easily recognizable even under low magni-95