Hormonal Control of Lactation
The problems involved in the hormonal control of lactation are extremely complex, and researches now in progress, while adding to our knowledge of the factors at work, have not led to the postulation of any all-embracing or coherent theory. Ample evidence for this statement is given in the comprehensive review by Folley,' to whose work we referred in a leading article on lactation in July of last year. At the moment the chief interest in this country is focused on the actions of oestrogens and pituitary fractions and their relations. It is by now well established that mammary development may be incited in most mammals by combined treatment with an oestrogen and progesterone. In general, oestrogens appear to stimulate duct development and progesterone appears to be responsible for alveolar growth. There is no clear-cut evidence that these actions are direct, for experiments in hypophysectomized animals. have given conflicting results in the hands of different workers. In this connexion Speert2 performed an interesting experiment by painting the left nipples of immature male monkeys with an alcoholic solution of oestrone, the right nipples being painted with alcohol alone. He found that the oestronetreated mammae enlarged while the control right nipples were uiaffected, which goes to show that the pituitary was not involved. This conclusion, however, at present applies only to the mammary glands of the immature male monkey, because one of the most confusing factors in research on lactation has been the quite different results obtained by similar procedures in different species and in the different sexes of the same species. The technique of unilateral inunction does, however, provide a method for testing the direct action of hormones absorbed through the skin without removing the animal's own glands, which inevitably results in undesirable and usually uncontrollable secondary effects. Turning to the question of the secretion of milk by the mammary glands when they are fully developed, the pituitary is found to be accepted as the most important factor at work. It is perhaps unfortunate that the early researches of Riddle showed that anterior pituitary extracts which initiate lactation in a variety of species would also cause the growth of crop-glands in the pigeon. This was made the basis of an assay method for preparations and was almost universally adopted. It is only lately that it has been appreciated that this method of assay has distinct disadvantages. It is now realized that an extract capable of stimulating the pigeon's crop-gland does not necessarily initiate milk secretion in mammals. The commercial preparations of prolactin at present available are usually standardized by the crop-gland response, a fact which may accouint for conflicting clinical reports. Folley' therefore proposes that the name " prolactin " should be confined to crop-stimulating activity, and Folley and Young3 suggest the term " galactopoietic factor " for the anterior pituitary fraction responsible for increasing the milk yield of an animal already producing milk. " Lactogenic " is applied to the initiation of lactation in hypophysectomized animals. Folley and Young in their experiments showed that injections of crude anterior pituitary extracts increase the milk yield in cows in declining lactation to a greater extent than do purer preparations containing seven times as much prolactin (crop-stimulating) activity. This leaves open the question whether prolactin is galactopoietic, but proves that there is a distinct galactopoietic factor in the pituitary apart from a prolactin, or a principle which, acting with prolactin, has a synergistic galactopoietic effect. The present difficulty
Further Observations on the Effect of Hypophysectomy on Lactation
The removal of the pituitary from a lactating rat leads promptly to a cessation of milk secretion. 1 Immature female rats treated with the anterior-pituitary-like hormone long enough to induce full development of their mammary glands secrete milk when the luteinized ovaries are removed, but not if the pituitary is removed at the same time. 2 These observations seem to support the view of Riddle 3 and others who believe that lactation is controlled by a pituitary hormone, prolactin. Less easily reconciled with this view was the observation 4 that pregnant rats hypophysectomized 10 days before term showed milk secretion for a few hours after parturition. It seemed possible that in these last experiments pituitary function was partly replaced by some stimulus from the pregnant uterus. We found in 10 experiments that if the uterus was emptied by Caesarian section late in pregnancy, lactation set in within 36 hours; similar observations have been made in the guinea pig 5 and the goat. 6 In 6 other experiments, however, in which the pituitary was removed when the uterus was emptied, no milk secretion was observed. This indicates that milk secretion is not possible in the rat if both the fetuses and the pituitary are absent.
Assessment of some agro-technological parameters of cactus pear fruit ( Opuntia ficus-indica Mill . ) in Morocco cultivars
Cactaceae had always attracted attention by their strange shapes and important adaptability supporting extreme conditions. For this reasons, Fruit traits were measured on 13 cultivars growing in different locations in Morocco. Results show significant differences between the cultivars. The source of this variation was probably genetic without excluding the geographic effects. The Tamri, Berkan, Ait Baha cultivars showed small fruit dimensions and weight. In contrast, Sidi-Ifni M, Nador, Mohammedia and Ben Guerir were greater than 100 g by fruit. Sidi-Ifni M, Hoceima, Mohammedia and Nador, although larger, contained few seeds, about 200 seeds per fruit; while Tamri, Ait Baha, Safi, Meknes and Tafraout contained over than 230 seeds per fruit. High levels of juice about 62 ml/100 g pulp were obtained with Sidi-Ifni M, Nador, Mohammedia and Ben Guerir cultivars. Total sugars of the 13 cultivars were quite similar and pH was low in Tamri and close to neutrality in the rest of cultivars. Therefore, oil extracted from Opuntia ficus-indica seeds constituted 13.6% of the whole seed. Thin-layer chromatography in conjunction with gas-liquid chromatography-mass spectrometry revealed a relatively high degree of unsaturation, 83.32% and 16% for saturated fatty acid, with a linoleic acid content of 63.66% followed by oleic 18.34%, palmitic 12.84% and stearic acid 2.81%. Based on these results, O. ficus-indica seed oil appears to be a good potential source of edible oil for human and (or) animal consumption. Our investigation describes that Tamri and Tafraout cultivars are not really a commercial viable fruit due to low total soluble solids value and highest seeds number per fruit. Against Mohammedia, Sidi Ifni M and Nador cultivars proved to have the highest fruit weight, very good total soluble solids value and low number of seeds, these cultivars can therefore be planted for both fruit production and for harvesting of cladodes for animal feed.