Shape Of Gland Research Articles

Effect of gamma-rays on thymus nucleoprotein in solution.

Experiments were made on the effects of gamma radiation on the molecular weight and shape of soluble desoxyribonucleohistone froi calf thvmus glands. The molecular weights of nucleoprotein were determined by the method of light- scattering and had an average value of 22 x 10/sup 6/, with a maximum variation of 10% from one independent extraction to another. lrradiation also caused a decrease in viscosity, with no after effect, and no increase in UV absorption at 259 m mu . This suggests that a decrease in molecular size occurred wlthout denaturation of the nucleic acid of the complex. The first major effect of irradiation on the nucleoprotein complex appears to be dlssociation of the small protein molecules from the nucleic acid, which remains relatively intact until most of the protein is dissociated. The effect of changes in concentiation indicate that the dissociation process does not have the usual characteristics of an indirect effect. There was no evidence for denaturation of the nucleic acid in the irradiated nucleoprotein even up to 40 ev/phosphorus atom. (P.C.H.)

The Reproductive System of Some Florida Mosquitoes. I. The Male Reproductive Tract1

A comparative system of the anatomical arrangement was made on 10 species, namely, Aedes triseriatus, A. taeniorhynchus, A. fulvus pallens, A. infirmatus, Psorophora howardii. Culex pipiens quinquefasciatus, Deinocerites cancer, Uranotaenia lowii, Culiseta inornata , and Anopheles crucians . The chief differences found were in the shape of the accessory glands, the time of formation of mature spermatozoa, and particularly in the arrangement of the seminal vesicles. The accessory glands were oval, or elongate, or pear-shaped; in U. lowii and A. taeniorhynchus they were shaped differently in newly emerged males than in older ones. In the Psorophora , the Culex , and the four Aedes species the seminal vesicles were conjoined or fused throughout their length, but in C. inornata, D. cancer, C. lowii , and A. crucians they were separate, connected only at the posterior ends. In the species with conjoined or fused vesicles the transfer of spermatozoa was rapid (10 to 15 seconds) during mating, but this was prolonged to 45 minutes or more in three of the four species with separate vesicles; mating behavior was not observed in Anopheles crucians , which is strikingly different from all the other nine species in the size and musculature of its ejaculatory duct. Active spermatozoa were found in the seminal vesicles within 15 minutes after emergence in P. howardii, D. cancer , and U. lowii ; after 6 hours in A. taeniorhynchus, A. triseriatus, A. infirmatus, C. p. quinquefasciatus, C. inornata , and A. crucians ; and after 20 hours in A. fulvus pallens.

Sialography and surface anatomy of the parotid duct.

The many variations in shape and extent of the parotid gland are well known. The parotid gland is larger than indicated in textbooks. 14 Not only does this structure vary in different persons, but also on the two sides of the same person. 36 Hetzar's 15 finding of differences of the parotid glands in the two sexes and in persons of different ethnological origins could not be confirmed in children. 39 There exist, in addition to the main parotid gland, accessory and secondary glands. Their frequency is variously estimated from 1% (at operation) 1 and 19.7% of anatomical dissections 22 to about 50% seen by sialography. 4 Several basic types of anatomical configurations of the parotid gland and its duct system have been described by different authors. 15,22,29,31 The terminal alveoli of the parotid gland are connected with the intralobular duct through intercalated ducts. The intralobular ducts give rise to

Experimental and Natural Hybridization between Bufo terrestris and Bufo fowleri

In analysing populations in which interspecific hybridization is suspected, the systematist seeks out the similarities and dissimilarities between the parental species. The alleged hybrids are then evaluated in terms of the differential characters of the two species. Determining which and how many of the character differences are to be selected as criteria of hybridization constitutes the critical phase of the procedure. Two species may differ so widely that individuals of one group are readily separable from the other. The differences may relate to the presence or absence of several qualitative characters. Some of the quantitative characters may display no or little overlapping of values when the measurements are plotted. In this case, a index method (Anderson, 1936, 1949; Hubbs and Hubbs, 1943) may be employed and it may be safely inferred that individuals with intermediate values represent products of hybridization. In other cases, the differences between two species may be such that there is considerable overlap when the values for any single character are plotted. Bufo terrestris and Bufo fowleri are two such entities. Few of the morphological differences between them are absolute, in the sense that one species possesses a characteristic that the other entirely lacks. A unique morphological feature of B. terrestris is the knob-like swellings on the posterior ends of the interorbital cranial crests. For the most part, however, the differences between B. terrestris and B. fowleri are ones of degrees. The two toad species differ in the size and distribution of warts, the extent of ventral spotting, the shape and coloration of the parotoid glands, the configuration of the snout, and other variable quantitative traits. These characters overlap broadly. The paucity of well-defined morphological differentials between the two species renders difficult the detection of hybridization in sympatric areas. Convincing data requires the demonstration that experimental hybrids between the two species resemble individuals collected in mixed breeding aggregations. The data reported herein deal with the success attained in reconstructing experimentally the suspected natural hybridization between B. terrestris and B. fowleri in southeastern Louisiana and adjacent Mississippi. Controlled cross-breeding experiments revealed the morphological features of hybrid individuals, as well as provided the

Durable whole mounts of sebaceous glands colored with oil blue N.

Studies of the distribution, abundance, size and shape of sebaeous glands are most readily made with relatively permanent whole mounts of skin samples which are: fixed in 10% formalin, washed, stained 8–16 hours with oil blue N (2 parts sat. oil blue N in 60% isopropanol: 1 part water), washed, dissected free of obscuring connective tissue, washed, and mounted on slides in glycerol gelatin. After 2 or 3 days, the edges of the cover glass are sealed with clear lacquer.

The effects of distention of the intestine upon the shape of villi and glands

The effects of distention of the intestine upon the shape of villi and glands