Non-lactating Gland Research Articles

Differences in the ribosomes prepared from lactating and non-lactating bovine mammary gland.

1. Ribosomes prepared from bovine lactating mammary gland are able to synthesize protein, whereas similar preparations from non-lactating glands are not. Washing the ribosome suspensions through a medium containing 0.5m-ammonium chloride enhanced their ability to incorporate phenylalanine into polyphenylalanine. 2. Ribosomes isolated from non-lactating bovine mammary gland, in contrast with those from rat liver and lactating mammary gland, contained significant amounts of extraneous nucleases. These enzymes could be removed by washing with a medium A buffer containing 0.5m-ammonium chloride. 3. Only those ribosomes from functionally active tissues were able to bind polyuridylic acid and phenylalanyl-tRNA.

Rat Mammary Gland Composition During Pregnancy and Lactation

Water, fat, and lactose concentration were studied at five-day intervals during pregnancy, parturition, and lactation in primiparous rats. A striking finding was the unchanging composition of the fat-free mammary tissue, as indicated by a constant proportion of dry weight for all of the periods studied. Thus, water content remained the same (80%) during pregnancy and lactation. The per cent fat of the gland declined steadily from 67% in the nonpregnant animal to 15% during lactation.Analysis of rat milk revealed fat and solids-not-fat concentrations to be about 13 and 17%, respectively. Lactose was found to be present in low amounts in the pregnant nonlactating gland, and to rise sharply at parturition. Both tissue lactose and milk lactose concentration rose significantly as lactation progressed, tissue values going from 596 μg/100mg on Day 1 to 939 μg/100mg on Day 20, and milk lactose from 12.3 mg/ml on the first day to 18.1 mg/ml on Day 15. Fresh gland weight, when corrected for the estimated amount of milk retained, was found to be essentially constant during mid-lactation. A micro milking apparatus is described.

THE USE OF AN IRON STAIN FOR THE STUDY OF ALVEOLAR DEVELOPMENT IN THE MOUSE MAMMARY GLAND

A method is described of using whole mounts of the mouse mammary gland with Gömöri's potassmm ferrocyanide – hydrochloric acid mixture for staining iron. Because iron accumulates in the epithelial cells in a granular form, most of the mammary gland tree of the mature nonlactating female mouse can be shown up clearly. The staining reaction is quick and uniform, muscle can be clearly differentiated in microdissection, and alveolar development can be estimated from the amount of iron retention in the nonlactating gland.

Effect of Diethylstilbestrol Dipropionate on Mammary Development and Lactation

Conclusions1. Progestin is not necessary for complete mammary development in cattle. 2. Estrogens will induce mammary development and copious milk secretion in cattle without injection of prolactin. 3. The turgidity of the udder may be used as an indicator of the secretory activity of the non-lactating gland. 4. The titer of estrogen determines its effect on the mammary gland. A low titer induces proliferation of the parenchyma and secretion of milk; a high titer suppresses lactation and brings on involution of the mammary gland.