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The human dental pulp was examined using a scanning electron microscope. The odontoblasts are pear-shaped and have a fine-grain surface structure. Tomes' process divides into fine branches before entering the predentin. Very few fibroblasts were found. These had stronger cell processes at the two terminal poles. Adhering to their surfaces were fine fibers. Collagenous and nerve fibers could not be accurately identified in the rich fibrillary network of the pulp. Stronger nerve fasciculi were readily observable through longitudinal sulci. Thinner fibers were seen to spread out in branches from some nerve bundles. The capillaries were observed to be surrounded by a sheath of fine fibrils.

With respect to steady increasing incidence of malignant tumors in Czechoslovakia the oncological program was established with the aim to achieve a gradual dispensarization of all population. The main part of the program is the secondary prevention through oncological examinations to find out early stages of tumors or precancerous lesions. The experimental examinations started in four districts and during two years 111,783 inhabitants from selected groups passed the screening. The examinations were also aimed on hypertension and diabetes. The first results revealed 0.2% new malignancies and 24% preneoplastic lesions. As far as hypertension and diabetes concerns there were 6,204 new cases of hypertension and 2,616 of diabetes. The examinations were supported by centers of clinical oncology created 3 years ago in all district and county hospitals. The task of the centers is not only the early diagnosis of all malignancies but also the application of a suitable therapy. For early diagnosis of some tumors there were established special committees which closely cooperate with the center. These are specially the committees for breast cancer and in some hospitals committees for malignant melanoma. The examinations will be gradually extended to other countries in CSR and in spite of many problems which remain to be solved we hope that all these arrangements will help in the fight against malignant tumors.

Twenty six patients with malignant skin melanomas were treated with an intratumorous injection of 0.1 ml BCG applicated in certain time intervals. Histologic changes in tumor tissue starting with dystrophy and necrosis of the cells and ending with the formation of a granular tissue replacing the tumor are described. In one case the untreated satellite localized 2 cm from the injected tumor disappeared. The results indicate that the reaction of the cells on the applicated vaccine varied. In some tumors dystrophic changes and necroses were very large, in others they were of a lesser extent, but in all the process ended with the formation of a granular tissue. The mechanism of the action of BCG is discussed. For the time being, it seems that the intratumorous application of BCG is a useful adjuvant therapy.

A freeze-etch study of nuclear pores performed on human lymphocytes, epidermal and corneal cells, on hamster fibroblasts, on rat and hamster sarcoma cells and cells from a human malignant melanoma, revealed that the frequency of pores as a part of very important biological cellular structures increases in proliferating cells, and that there is a statistically significand difference between normal and tumor cells. Once produced the pores maintain and their frequency practically does not change. The pores are randomly distributed on the nuclear envelope. Markham rotating method revealed an octa- or nonaedric outside shape of the pores and round inner margin with eight or nine granules. One bigger granule was found in the center of the pores. The granule is with a great probability filamentously attached to the margin of the pore. Fibrillar structures running to the pores on inner surface of nuclear envelope as far as the chemical composition of granules need special cytochemical examinations.

Histological classification of human skin malignant melanoma as recommended by WHO melanoma group renders the first useful orientation in regard to the biological behavior of the tumor, but it cannot give any further clinical outlook. It would be therefore desiderable to complete the histological examinations with enzymatic and immunologic examinations performed during the treatment of the patient and thus try to gain a basis for a prognostic evaluation.

Breast cancer is the second commonest tumour in Czechoslovakia and its incidence is increasing. In 1965 the incidence was 32 per 100, 000 but by 1975 it was 45 per 100, 000. (Editorial note: These figures are low - perhaps they relate to cases per total population. It would be more usual to give the incidence for women - which I should expect to be higher.) In Czechoslovakia the cancer control programme concentrates on prevention and early detection. Despite some evidence of success, it is still a serious problem that some women report their symptoms late and prognosis is therefore poor. Public education activity needs to be developed - not only in Czechoslovakia but throughout the world. The WHO should encourage world-wide co-operation in this respect.

In the scanning electron microscope in detailed structure of the dentino-enamel membrane can be investigated. This membrane is mineralized. After partial demineralization it covers the bottom of prism margins and enables their firm anchoring on the surface of dentin. Here the prism bundles are anchored in dishlike formations, on the bottom of which a network of fibers is found, covered by the dentin-enamel membrane. Through artificial fissures in the membrane the above mentioned network of fibers can be seen.

The regeneration capacity of the filiform papillae of the rat tongue was studied after destruction through abrasion in 18 rats after time intervals of 1 1/2 days until 7 months. By abrasion were destroyed the epithelial layer, the tunica propria mucosae and part of the muscle layers. Lightmicroscopic investigation showed formation of new filiform papillae, similar in structure to the normal tissue. Scanning electron microscopic investigation brought further details. It showed clearly that in the regeneration area the newly formed filiform papillae were irregularly distributed and of different shapes. These studies make it clear that newly formed epithelial as well as connective tissue has a generally coded property to form new filiform papillae. No fungiform papillae were ever seen to regenerate. It is concluded that these are higher differentiated organs with no capacity to regenerate.

A new human cell line of malignant melanoma (MJM) was established with the use of the in vitro fragment technique. It has been maintained over 34 months of continuous cultivation. Three types of cells can be recognized by light microscope. The epitheloid elements predominate, less frequent are fibroblastoid and giant multinuclear cells. The pigment production is not macroscopically visible. Over 60 per cent of analyzed metabphases showed hyperdiploid number of chromosomes, the rest was mostly tetra and hexaploid. No marker chromosomes were detected. The growth studies indicate the MJM cells have 63-hr doubling time. Cytochemistry revealed positive pigment or propigment granules in 36 per cent of cells. Ultrastructural studies did not detect melanin granules but some particles resembling atypical premelanosomes and melanosomes were recognized in some sections.

Filiform papillae are described in a 4-month-old fetus, in premature children (22-36 weeks) and in children who died soon after birth. Under the scanning electron microscope papillae filiformes often displayed tubercles appearing either independently or arising near the base of the tongue from obliquely running ridges dividing afterwards into tubercles. Some SEM specimens showed further development of papillae from tubercles and cylindrical papillae into papillae quite similar to those found in a fully developed tongue. They were however significantly smaller. Filiform papillae are more varied in the stage of development than in the fully developed tongue, because developmental stages could be observed here. We could also see spheroid papillae with tiny processes on the top or large scales on the circumference besides the above mentioned formations. Even places with "hairs" resembling those of the hair-tongue were found. These atypical findings were most likely pathological changes resulting from hypoxia before death.

Lamellae, tufts and cracks were found in the enamel near the dentionenamel junction. When investigated by the scanning electron microscop, lamellae and tufts were very similar to each other as to their structure. Lamellae appeared in two kinds: 1. Organic material originating in the dentionenamel membrane filled the whole space. 2. The space was empty, yet an organic membrane was covering the walls of adjacent prisms. Tufts and lamellae differed merely in their lenght. The walls of the cracks lacked organic material, the prisms being damaged or their course interrupted.

Forty-five thousand three hundred thirteen patients treated in our Institute during the period 1949-1982 were retrospectively analyzed in regard to the appearance of secondary tumors after therapy. Eighty-seven (0.19%) tumors were found, 71 (81.6%) being secondary and 16 (18.4%) simultaneous. Fifty-one (71.8%) tumors were lymphoid, 20 (28.1%) nonlymphoid. Thirty-seven (52.1%) tumors appeared after radiotherapy, 13 (18.3%) after chemotherapy alone. Secondary tumors appeared mostly after 6 years. The prevalence of lymphoid secondary tumors may be explained as a compensatory proliferation of surviving cells progressing to neoplasia. Cytostatics and ionizing radiation as both the initiators and the promoters of malignancy, have besides person's susceptibility a triggering function. From these aspects before any treatment is started all possible carcinogenic factors should be taken into consideration and less carcinogenic procedures with keeping up a full effectiveness should be chosen.