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Biomedical subjects

V F Puchkov

Publications and source records attributed to V F Puchkov.

9 recordsLinked to original sources
PubMed1979

[Estrous cycle of the Arctic lemming (Dicrostonyx torquatus Pall.) maintained and breeding under laboratory conditions].

Reproductive functions and life at laboratory conditions were studied in the lemming. Standard cage-terrariums with a wheel for motion and a plate for drinking are quite convenient. The main ration includes: hay, oats with some carrot added, some apples two--three times a week, sunflower seeds. The animals feel well and reproduce at +8 degrees and +20 degrees in well ventilated rooms. The estrous cycle in lemming females studied by microscopy of vaginal smears is not regular. Only two stages are definitely seen: diestrus and estrus. Intermediate stages--proestrus and metaestrus--can be identified by a successive studies of vaginal smears of the same animal.

Animals↗
PubMed1979

[Spur development in chick embryos].

Normal development of spurs and horny squamae have been studied in histological preparations obtained from the skin of tarsometatarsus in 8--16-day-old embryos. During the first, initial stage of development, by means of rearrangement of cellular matter and cell migration, three main parts of the spur are layed down -- the horny cover, the spur body and the fibrovascular cushion. For the second stage, vigorous growth of the spur germ at the expense of proliferative activity of its cells is characteristic. At the third stage (after hatching) in males, the spur body outgrows and the bony core is formed. Morphogenesis of the horny squama can be devided into two stages. At the initial stages by means of condensing cellular elements, squamous papilla and horny shell are layed down. The fibrovascular cushion is absent. The second stage is similar to the spur one and is characterized by growth of all the germ parts at the expense of cell proliferation. Comparing morphogeneses of the squama and the spur, it is possible to conclude that phylogenetic transformation of the squama into the spur is performed by two means (modi) of phyloembryogenesis: by means of adding new signs of development to the initial terminal stages of its morphogenesis.

Animals↗
PubMed1978

[Critical period in the work of the form-inducing apparatus of the lens in chick embryos, detected after chloramphenicol application].

The inhibitor of protein synthesis chloramphenicol (2 mg/egg) was applied to elucidate the critical period in the chicken lens development. Chloramphenicol injected before incubation and at 24, 30 and 48 h of incubation did not prevent the formation of parts in the lens-inducing apparatus (the optic vesicle, and the presumptive lens ectoderm), but the injection at the stage of 24--30 h of incubation resulted, in many survived for 5--7 days of incubation, in lack of the lens. Therefore, it is possible to speak about a disturbance in the activity of the inducing apparatus during the period of determination, or about a critical period of the lens development.

Age Factors↗
PubMed1977

[Comparison of the effect of chloridin on rat embryos during postimplantation periods of development in vivo and in vitro].

The effect of chloridin (2,4-diamino-5-parachlorophenyl-6-ethylpyrimidine) on the rat embryos developing in the maternal organism and on the embryos explanted 24 hrs after the treatment in the nutrient medium (homologous blood serum) was compared. The pathological processes both in vivo and in vitro were shown to be similar. The number of atypical and died embryos in vitro was, however, much higher, apparently due to the absence of some protective membranes in the cultivated embryos.

Abnormalities, Drug-Induced↗
PubMed1976

[Critical periods in the development of spurs in light of the theory of phylembryogenesis].

Two critical periods have been established in the development of spurs representing a derivative of the corneous squama. During the first period the exposure to x-rays results in the development of the corneous squama instead of the spur, and the same exposure during the second critical period completely suppresses the development of the spur. These periods seem to correspond to the truning-points in the chain of morphogenetical processes of the spur formation associated with phylembryogeneses. Department of Embryology, Institute of Experimental Medicine, USSR Acad. Med. Sci., Leningrad.

Animals↗
PubMed1976

[The development of yolk circulation in normal rat embryos].

To reveal the developing vessels of the yolk placenta the erythrocytes were stained with benzidine. The development of vessels was studied in vivo and in transplantation of embryos in the homologous blood serum. The pattern of branching of blood vessels in the yolk sac of 12-day embryos was established. The development of the blood circulatory system started on the 9,5 day (the anlage of sanguineous islands), the definitive state was acquired by the 12th day. The development of vessels in vitro after removal of the parietal layer of the placenta is dependent on the mophological stage at the moment of transplantation. In explantation of embryos with 2--3 pairs of somites which are being already formed, the yolk vessels develop as those in control. In transplantation of presomite embryos the development of vessels is sharply disturbed, in transplantation of embryos of the egg cylinder stage the vessels are not developed. The inducing role of the yolk placenta perietal layer in the development of blood vessels in the vascular layer is supposed.

Animals↗
PubMed1975

[Disorders in the development of the crystalline lens in chick embryos following exposure to insulin].

Inection of insulin into the chicken egg-white in dosage of 4 i. u. during the 1st - 14th days of incubation results in degenerative changes in the lens. Injection of insulin during the 1st day of incubation (before the beginning of eye differentiation) fails to prevent development of the eye vesicle and determination of the lens. The morphogenesis of the lens goes normally up to the 10-13th days of incubation. From this moment abrupt degenerative alterations make their appearance as well as destruction of the lens fibres. When the lens is affected by insulin the destruction is observed on the following day. The mechanism of insulin effects upon the lens seems to be as follows: Exogeneous insulin remains in the embryo tissues for along time. When the tissues are preparing to accept endogeneous insulin and become susceptible to it (the 10th-11th days of incubation) exogeneous insulin begins its pathological influence on the lens fibres. After the 13th-14th days of incubation endogeneous insulin comes into the blood. Against the background of exogeneous insulin it results in excessive increase of concentration of insulin in the embryo tissues and great degenerative changes in the lens.

Animals↗
PubMed1975

[Dating pregnancy times in rats and the effect of ovum supermaturation on the quantity of live embryos].

The fecundity of white rats was compared for the night and morning matings (late and early). The mating of animals at the stage of oestrus for 1.5 hrs early in the morning is the optimum one for obtaining females with the precisely dated time of pregnancy. The progeny of females fertilized after 10-11 hours in the morning, i. e. 9-11 hrs after the ovulation, decreases almost twice at the expense of embryonic mortality both prior and after the implantation due to the low viability of "overmatured" eggs.

Animals↗