Yasuaki Nishizuka

Thymus and Reproduction: Sex-Linked Dysgenesia of the Gonad after Neonatal Thymectomy in Mice

Neonatal thymectomy of mice, when no ectopic thymus existed, constantly resulted in developmental arrest of the ovary but not of the testis; it also caused sterility in the female. The ovaries of thymectomized mice were extremely small and were characterized by absence of follicles and corpora lutea. Such an ovarian dysgenesia was observed when the mice were thymectomized at 3 days of age, but not at 7 days or later; it was prevented by thymus grafting.

Persistence of responsiveness of adult mouse mammary gland to induction by embryonic mesenchyme

Abstract Persistence of the capacity for embryogenic morphogenesis in adult mammary epithelium was demonstrated by allowing it to interact with grafted embryonic mesenchyme in vivo. When 14-day embryonic mammary or salivary mesenchyme was transplanted in the mammary gland of syngeneic young adult virgin mice, organogenetic development of the mammary epithelial cells occurred responding to closely attached mesenchyme. An early change, within 2–4 days, that was observed equally in both types of the mesenchymes was proliferation of mammary epithelial cells in multiple layers resembling rudimental architecture. Subsequently, ductal branching occurred from the rudimental architecture by mesenchyme-dependent branching pattern, of mammary gland type with mammary mesenchyme and of salivary gland-like type with salivary mesenchyme. This developmental response did not require hormones secreted from ovaries since it was observed similarly in ovariectomized mice. The mammary epithelium at the lactating stage did not show such a potential to the transplanted salivary mesenchyme.

Dual origin of mesenchymal tissues participating in mouse mammary gland embryogenesis

Abstract By the 14th day of gestation, two different mesenchymes can be identified which affect mouse mammary gland embryogenesis: the fibroblastic mammary mesenchyme (MM) closely surrounding the epithelial rudiment, and a condensed mesenchymal tissue (FP) appearing separately, posterior to the mammary rudiment, the precursor tissue of the fat pad. Late on the 16th day, the mammary epithelium (ME), surrounded by MM, starts to elongate, puts out branches, and penetrates the FP. A fatty substance appears in the FP at this stage. Interaction between ME and FP is necessary for typical mammary morphogenesis. When 17-day ME is combined with 14- or 17-day FP, the resulting mammary gland has the normal mammary pattern, but when 17-day ME is combined with 12- to 17-day MM, a ductal hyperplasia is formed by frequent branching, without the “stretching out” of these ducts. All the glands formed by combining ME with either FP or MM will lactate, if the mice carrying the grafts are allowed to mate and give birth. Adult ME also shows a different response to MM and FP.

Polyester wax embedding and sectioning technique for immunohistochemistry.

We have developed a method useful for immunohistochemical studies by combining tissue fixation with buffered neutral formalin and polyester wax embedding. Buffered neutral formalin fixation preserves cell and tissue fine structure, and also the antigenicity of unstable enzymes. Polyester wax embedding makes possible thin serial sections of various tissues and preserves antigenicities for at least 6 months. We have demonstrated using this technique the localization of alpha-amylase in mouse salivary gland, parietal-cell specific antigen in mouse glandular stomach, and DNA polymerase alpha and beta in chick tissue.

A pituitary-salivary mixed gland induced by tissue recombination of embryonic pituitary epithelium and embryonic submandibular gland mesenchyme in mice☆

Renal subcapsular syngrafts of Day 9 to 11 mouse embryonic pituitary epithelium with Day 14 mouse embryonic submandibular gland mesenchyme produced mixed organs that include residual cleft structure surrounded by anterior pituitary cells some which are stained by anti-ACTH antiserum and submandibular gland-like structure with differentiated acinar cells which are stained by anti-alpha-amylase antiserum. However, when Day 8.5 or 12 embryonic pituitary epithelium was recombined with submandibular gland mesenchyme and syngrafted, development of submandibular gland-like or anterior pituitary tissues resulted, respectively. Thus, during organogenesis of the mouse anterior pituitary, there exists a developmental stage (Day 8.5-11 in utero), when prospective pituitary epithelium can respond to heterotypic submandibular gland mesenchyme with the development of a submandibular gland-like tissue.

Reproductive tract abnormalities in female mice treated neonatally with tamoxifen

Immature female mice of the NMRI strain were treated with 20 micrograms/day of tamoxifen or vehicle for the first 3 days after birth. At 90 days of age, vaginas, uteri, and ovaries were examined histologically. A benign epithelial change, vaginal adenosis characterized by abnormal growth of columnar epithelium with glandular structures, was found in all of the tamoxifen-treated mice. Anatomic anomalies such as hypospadias, cervical hypoplasia, uterine hypoplasia, and absence of corpora lutea also were commonly observed. Such abnormalities were not found in the control mice.

Symbiotic culture of mouse leukaemias: Regulation of cell interaction by an activity of serum

SummaryTwo symbiotic tissue culture cell lines of mouse leukaemias have been established in which survival and growth of leukaemic cells depended upon close association with co-cultured non-neoplastic adherent cells. Electron microscopy of the symbiotic cultures revealed that leukaemic cells were trapped either by tentacle-like cytoplasmic projections or by ruffled membrane of the adherent cells and many leukaemic cells were found to be underneath the adherent cells. This type of cell interaction was defined as pseudo-emperipolesis (P-EMP) to distinguish it from “true” emperipolesis involving penetration of living cells in other cells. The degree of P-EMP was quantitated by measuring the percentage of adherent cells trapping one or more leukaemic cells beneath their cytoplasm. Quantitative analysis of P-EMP demonstrated that its occurrence was promoted by a heat-stable non-dialysable factor in fresh serum. Withdrawal of the serum factor resulted in rapid liberation of the leukaemic cells that were present beneath the adherent cells. The morphology of symbiotic cultures was therefore determined primarily by the level of the serum activity in the system. By incubating with various cells at 37° C., the serum activity was cleared from medium whereas the leukaemic cells isolated from symbiotic lines specifically lacked this function. The possible relevance of cell interactions in symbiotic cultures of leukaemias to the microenvironmental control of haemopoiesis was discussed.

Unilateral development of ovarian tumour in thymectomized Swiss mice following a single injection of 7,12-dimethylbenz(a)anthracene at neonatal stage.

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Hypertrophic gastritis with hypergastrinemia and protein loss after neonatal thymectomy in mice

SummaryHypertrophic gastritis, histologically characterized by a depletion of parietal and chief cells and by varying degrees of lymphocyte infiltration along the thickened muscularis mucosa, could be induced by neonatal thymectomy (Tx) without any additional treatment in about 50% of mice (C3H/HeMs × 129/J)F1 (C3.129). The thickness of the mucosa in gastritic mice increased with age, forming giant folds. In Tx mice with an early stage of abnormal mucosal folds at 6 months of age, numbers of parietal cells per mucosal tissue unit area (parietal cell densities) and ratios of parietal cells to mucous cells became lower than in control mice, and serum gastrin levels became contrastingly higher with the increasing severity of gastritis. Circulating antibodies against parietal cells (APA) were detected by indirect immunofluorescence (IFL) in the mice. A good correlation was observed between APA and gastritis: APA with high titers (more than 1,000-fold dilutions) appeared when severe lesions were found. In mice with giant mucosal folds at 18 months of age, serum protein levels were within normal limits, but fecal clearance rates of125I-labelled polyvinylpyrrolidone (125I-PVP) were significantly increased. These results suggest that the hypertrophic gastritis induced by neonatal Tx is characterized by hypergastrinemia due to parietal cell depletion caused by the presence of circulating APA and the protein loss from the hypertrophie mucosa. Both histological and physiopathological similarities were found between the gastritis in the mice and Menetrier’s disease in man.

Enhancement of 7,12-dimethylbenz(a)anthracene leukaemogenesis in mice by neonatal injection of cortisone acetate

Enhancement of 7,12-dimethylbenz(a)anthracene leukaemogenesis in mice by neonatal injection of cortisone acetate