| Ovarian hormones are the prominent mammogens, but their actual effects on the mammary gland are not very well illustrated. However, the results of this study suggest that in ovariectomized Swiss mice progesterone alone reversed the absence of the ovaries as measured by biochemical indices (mammary wet weight and dry fat free tissue). Estradiol was more selective in that it failed to increase the total size of the mammary gland, but it stimulated extensive milk duct branching; moreover it synergized with progesterone to enhance further mammary growth. Porcine relaxin, in a dose-dependent manner, induced significant mammary growth alone, by stimulating a higher accumulation rate of mammary fat pad as well as other stromal components and parenchyma when administered in the highest dose (80 GPU). Porcine relaxin synergized with both estradiol and progesterone to augment mammary glad growth to the highest rate as judged by biochemical and morphologic indices. A new configurational structure has been described and is termed "THE SPREADING HOLLOW"; it extends form the tip of the end bud forming a hollow with clear fluid residing between the epithelial layer and the basement membrane. This could be responsible for the proliferative process of the mammary duct providing the necessary chemical factors needed as well as the soft matrix for the epithelia to move forward without obstacles. |
