The Distribution of Cell Types in the Anterior Hypophysis During Late Pregnancy and Lactation

WITHIN the last few years considerable evidence has accumulated from bio-assays (Hurst and Turner 1942) which shows that the lactogenic content of the anterior hypophysis increases markedly in mammals about the time of parturition. In some forms the increase has been observed during pregnancy, whereas in others no notable increase occurs until the time of parturition or soon afterwards. There have been relatively few cytological studies of the hypophysis from pregnant and lactating animals and attempts to correlate the cytology with assay results have been sadly neglected. Although Haterius (1932), and Dfcsclin (1936) did not make differential cell counts, they reported that the hypophysis of the rat presents essentially the same picture during pregnancy and lactation. Weis (cited by Kirkman 1937) observed that in the guinea pig hypophysis the acidophiles increase in the first part of pregnancy, and that at parturition the acidophiles decrease while the basophiles increase in number.