DEFECTIVE MAMMOPOIESIS, BUT NORMAL HEMATOPOIESIS, IN MICE WITH A TARGETED DISRUPTION OF THE PROLACTIN GENE

Prolactin (PRL) has been implicated in numerous physiological and deve lopmental processes, The mouse PRL gene was disrupted by homologous re combination. The mutation caused infertility in female mice, but did n ot prevent female mice from manifesting spontaneous maternal behaviors , PRL-deficient males were fertile and produced offspring with normal Mendelian gender and genotype ratios when they were mated with heteroz ygous females, Mammary glands of mutant female mice developed a normal ductal tree, but the ducts failed to develop lobular decorations, whi ch is a characteristic of the normal virgin adult mammary gland, The p otential effect of PRL gene disruption on antigen-independent primary hematopoiesis was assessed, The results of this analysis indicated tha t myelopoiesis and primary lymphopoiesis were unaltered in the mutant mice, Consistent with these observations in PRL mutant mice, PRL faile d to correct the bone marrow B cell deficiency of Snell dwarf mice, Th ese results argue that PRL does not play any indispensable role in pri mary lymphocyte development and homeostasis, or in myeloid differentia tion. The PRL-/- mouse model provides a new research tool with which t o resolve a variety of questions regarding the involvement of both end ocrine and paracrine sources of PRL in reproduction, lactogenesis, tum origenesis and immunoregulation.