THE REPRODUCTIVE ORGANS 89 



It has been supposed that the cells undergo periodic changes 

 of such a character that at certain times they may be more, 

 at others less, abundant or conspicuous. For example, they 

 are stated to reach their greatest development during preg- 

 nancy and lactation. 



The cells have a typically glandular appearance. They 

 have an abundant blood supply and contain granules. These 

 are of various kinds, as indicated by their staining reactions. 

 There is an abundant chondrioma and enclosures of a lipoid 

 character, siderophil protoplasm, and distinctly polychromatic, 

 large, round nuclei. The chondrioma is made up of chon- 

 drioconta and mitochondria. It undergoes important modi- 

 fications in the course of the evolution of the cell. The 

 granulations, at first few, increase in number in the later 

 stages ; the fatty products are the result of a chemical change 

 in the mitochondrial substance. The lipoid enclosures prob- 

 ably represent the products of secretion (Athias). 



When the theory of internal secretion on the part of the 

 ovary had once become generally accepted, and when the 

 organ was found to contain, in addition to the follicles, certain 

 other cells of a glandular appearance, it was natural that 

 these last should be charged with the function of internal 

 secretion. But so far no hypothesis in regard to them has been 

 put forward which has much direct evidence in its favour. 

 Perhaps the best accredited of such hypotheses is that the 

 interstitial cells preside over the nutrition of the reproductive 

 organs (e.g., the uterus) and are responsible for the appearance 

 of the secondary sexual characters. 



In birds there seems to be some doubt whether the " inter- 

 stitial " cells can be regarded as secretory elements. They 

 appear to contain hsemopceetic centres. 



Bell urges that " femininity " is dependent, not only on 

 influences arising from the ovary, but on all the various 

 internal secretions. The relations of the thyroid gland and 

 the adrenal to the female reproductive system are treated in 

 other chapters (pp. 241, 400). The pineal is alleged to have 

 an influence on sexual precocity (p. 390). It is believed that 

 the pituitary and the thymus influence the metabolic functions, 

 determining the onset of puberty. The question is rendered 

 complicated by the influence of the various internally secreting 

 organs upon each other (p. 395). 



