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TWO TEXT FIGWS AND TWO PLATES (FOUR FIGURES)I n a preliminary report (Pencharz and Long, '31) on the effect of hypophysectomy in the pregnant rat, it was stated that removal of the anterior and posterior portions of the gland between the eleventh and twentieth days of pregnancy was followed by a lengthening of the gestation period by from 3 to 4 days. On the other hand, in those instances in which fragments of the gland had been inadvertently left behind, gestation was normal or disturbed, depending upon the amount of tissue left in situ. Since that announcement, experiments have been extended to include earlier stages of pregnancy, and the present paper is a detailed report of the earlier observations and of the more recent studies.I n the paper referred to above it mas also stated that in those instances in which the operation was complete and no tissue could be detected at autopsy and by serial sections of the pituitary region, the rats died at the end of a prolonged gestation period without being able to expel their young, In the more recent studies a number of animals survived, dead and living young being born several days beyond term.So far as the writers are aware, the literature contains an account of only two short series of experiments dealing with the effects of total hypophysectomy in the pregnant animal, The first group of experiments was carried out by Aschner in 1912 on three pregnant dogs, in which ablation of the hypophysis was followed by abortion in from 3 to 12 days. after the operation.

Objectives Investigation of mechanism related to excessive invasion of trophoblast cells in placenta accreta spectrum disorders (PAS) provides more strategies and ideas for clinical diagnosis and treatment. Materials and Methods Blood and placental samples were collected from included patients. The distribution and expression of CXCL12, CXCR4 and CXCR7 proteins in the paraffin of placental tissue in the included cases were analysed, and we analyse the downstream pathways or key proteins involved in cell invasion. Results Firstly, our results determined that CXCL12 and CXCR4/CXCR7 were increased in extravillous trophoblastic cell (CXCL12: P < .001; CXCR4: P < .001; CXCR7: P < .001), and the expression levels were closely related to the invasion depth of trophoblastic cells. Secondly, CXCL12 has the potential to become a biochemical indicator of PAS since the high expression of placental trophoblast CXCL12 may be an important source of blood CXCL12. Using lentivirus‐mediated RNA interference and overexpression assay, it was found that both chemokine CXCL12 and receptor CXCR4/CXCR7 are associated with regulation of trophoblast cell proliferation, migration and invasion. Further results proved that through the activating the phosphorylation and increasing the expression of MLC and AKT proteins in the Rho/rock, PI3K/AKT signalling pathway, CXCL12, CXCR4 and CXCR7 could up‐regulate the expression of RhoA, Rac1 and Cdc42 proteins to promote the migration and invasion of extravillous trophoblastic cell and ultimately formate the placenta accrete compare to the normal placenta. Conclusions Our research proved that trophoblasts may contribute to a PAS‐associated increase in CXCL12 levels in maternal blood. CXCL12 is not only associated with biological roles of PAS, but may also be potential for prediction of PAS.

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