Sialographic investigations on the anatomy of mouse parotid glands

The anatomic structure of the mouse parotid gland was investigated by a sialographic method. The mouse parotid was infused with 0.4-0.6 micron grains of barium sulfate sol as an x-ray contrast medium and extirpated. The excised gland was flattened and imaged by using 10 or 25 k Vp x-rays. Twelve different strains of male mice 12 weeks old were investigated. It was found that the mouse parotid gland has the club-shaped major lobe and the accessory lobe and that the major lobe is further divided into three lobes: the superior lobe which extends underneath the ear, the middle lobe, and the inferior lobe which extends toward the submandibular gland. The accessory lobe began from the proximal part of Stensen's duct and extended to underneath the eye. The presence of the accessory lobe, the shape of the major lobe, and the branching pattern of the parotid duct tree were mouse strain dependent.     

The effect of hypophysectomy on the immune response

Twenty-one-day-old rats were hypophysectomized or sham-operated and challenged with sheep red blood cells 5 or 21 days after operation. Although the sizes of the bodies and lymphoid organs were greatly decreased in the hypophysectomized animals no significant difference was found in the numbers of plaque forming cells or serum antibody titres against the sheep red blood cells. The hypophysectomized rats showed a cell depletion in the perifollicular zone of the spleen follicles, but no obvious histological changes in the thymus.

It is concluded that pituitary hormones are not directly necessary for the formation of humoral antibodies.

     

The effects of the carcinogen, 1,2-dimethylhydrazine,on turnover 3H-thymidine labeled cells from mucosal glands of mouse colon

1,2-dimethylhydrazine (DMH), administered weekly to mice for 20 weeks, induces tumors in the distal segment of colon. Tumors are preceded by enlargement of the mucosal glands resulting from increases in the number of total cells and ³H-thymidine labeled cells/crypt. Cells located in the crypt base normally undergo 2–3 divisions as they migrate toward the lumen, and they become post-mitotic in the upper crypt. It is not known if cells in these eniarged crypts have rates of turnover similar to cells in normal crypts. Groups of w/s female mice were treated with DMH (20 mg/kg body wt) for 3,8, or 16 weeks; controls were given 0.001 M EDTA. After treatment, the animals were injected with ³H-thymidine and killed one hour or 1,2,4,7 or 17 days later. Autoradiographs were prepared from sections of distal colon. The total cells/crypt column in 30 crypts/animals were counted. Crypts were divided into 10 equal segments based on the crypt length and the labeled cells/segment were counted. The relative number of labeled cells and the distribution of these cells within crypts were similar in DMH-treated and control animals after one hour. However, as the cells migrated toward the lumen, the number of labeled cells doubled after 2 days and tripled after 4 days in DMH-treated animals but only doubled during the 4 days in controls. This difference was caused by retention of an increased number of dividing cells in the lower 4 segments of the crypts and suggests an increase in those cells that divide twice. In addition, increased numbers of labeled cells were retained in the upper 3 segments of DMH-treated animals after 4 days. These findings indicate that the crypt cells of DMH-treated animals are generally more immature than those of controls and this immaturity contributes to the enlargement of mucosal glands during carcinogenesis.     

The effects of bilateral adrenalectomy or hypophysectomy of the foetal lamb in utero.

1. Foetal hypophysectomy or bilateral adrenalectomy, carried out in utero at about 100 or 125 days gestation respectively, increased the length of gestation in sheep. It was confirmed that pregnancy was not prolonged significantly if hypophysectomy or adrenalectomy was carried out on one of a pair of twins. The hypophysectomized foetus was, however, smaller and the adrenalectomized foetus larger, than the unoperated twin. 2. In about half of the previously operated foetuses intravascular catheters were inserted into both mother and foetus, either at about 125 days, for a comparison with normal catheterized foetuses, or during the post-mature period. Both adrenalectomized and hypophysectomized foetuses appeared to have little resistance to stress or infection and the majority survived only 1-2 weeks after the insertion of catheters. 3. Maternal peripheral plasma oestrogen, progesterone and corticosteroid concentrations did not appear to be altered by either foetal hypophysectomy or adrenalectomy and were maintained in the normal range during prolonged gestation. 4. Foetal plasma oestrogen concentrations were significantly lower after hypophysectomy or adrenalectomy than values found in control lambs. Plasma progesterone values were low in all three groups of foetuses. 5. Plasma corticosteroid concentrations after foetal hypophysectomy (12-6 ng/ml.) or adrenalectomy (14-7 ng/ml.) were in the same range as the values for control lambs before the pre-partum rise (14-6 ng/ml.). However, there was a small but significant maternal-to-foetal plasma corticosteroid gradient in the two operated groups whereas this difference was not found in the control animals. 6. Tissue glycogen concentrations were measured in non-catheterized adrenalectomized and hypophysectomized foetuses. In these two groups, whether examined before 149 days or after prolonged gestation, liver glycogen concentrations were 30-40% of those in non-catheterized control foetuses at term. In other respects there was little apparent difference between adrenalectomized and control foetuses. 7. Hypophysectomized foetuses had significantly higher glycogen concentrations in heart, skeletal muscle and lung compared with control or adrenalectomized lambs. Plasma glucose and fructose values were also low in this group compared with control foetuses.     

The expression and localization of osteopontin in the mouse major salivary glands

The present study investigated the expression and distribution of osteopontin in the mouse major salivary glands. The level of osteopontin expression in the mouse submandibular gland was higher (12.7-fold) than that in parotid and sublingual glands at the mRNA level. By Western blot analysis, intense positive bands were seen at the predicted molecular mass (about 55 kDa) in all the major salivary glands, while an approximately 30 kDa band of osteopontin was detected only in the submandibular gland. Indirect immunofluorescent and immuno-electron microscopy analyses demonstrated the localization of osteopontin in the luminal (apical) membranes of acinar cells in all the salivary glands. Osteopontin was also localized at the lumen of acini in the submandibular gland. These results suggest that the expression of osteopontin in the submandibular gland is different from that in the parotid and sublingual glands and that osteopontin may be degraded in the mouse submandibular gland.     

Early histogenesis of transplanted mouse mammary glands

Summary Small mammary isografts from tritiated thymidine pretreated donors became disorganized within 24 hours of transplantation; isotope-labelled cells were dispersed in the mammary fat pad. At 72 hours after transplantation some aggregates of mammary cells were organized into mammary ducts with one or more epithelial cell layers. At 96 hours all stages occurred in individual transplants that were often disconnected, but only one mammary gland eventually developed from each graft.Supported by grants from the National Cancer Institute of Canada, the Medical Research Council of Canada and the Jane Coffin Childs Memorial Fund for Medical Research.The authors are indebted to Mrs. Sharon Griffin for her technical assistance.