Cysts of unknown etiology in marine fishes of the Northwest Atlantic and Gulf of Mexico

Results of light and electron microscopic examinations of cysts of unknown etiology (CUEs) occurring in the gills of Atlantic mackerel, red hake, white hake, cod, haddock, and silver hake are presented. CUEs were found also in gills and viscera of winter flounder, Atlantic croaker, spot, windowpane flounder, and sand lance. CUEs measured 150–400 μm in diameter and consisted of an external fibrous cuticle, usually a thick median band, and a central core that frequently contained eosinophilic vesicles. Structures resembling mitochondria were found in the band and in vesicles of the core, but no other organelles were apparent. Cytochemical staining and ultramicroscopy revealed aggregates of glycogen in the core ground substance; no structural components were stained with Sudan black B or by the Feulgen technique. Extensive encapsulation of CUEs by fibroblasts was typical. Of 717 mackerel examined, 76.8% had CUEs in the gills; numbers ranged from 1 to 353 per fish. The prevalence and intensity of occurrence of CUEs increased with the age of the mackerel.

Myocardial Feulgen-DNA levels and capillary vascularization in hypoxia-exposed rats

Male abino rats were exposed to simulated altitude of 18,000 ft (380 Torr) for 1 day to 8 wk. Histological sections of heart ventricles were stained by the Feulgen technique and amounts of Feulgen-DNA were determined cytophotometrically. Heart weights, relative to body weights, increased over controls at all exposure periods, as did myocardial capillary vascularization. Ninety percent of cardiac muscle nuclei were found to contain tetraploid amounts of DNA. All nuclei exhibited a high degree of chromatin dispersion in exposed and unexposed rats, which reflects a highly reactive metabolic state of cardiac cells in both groups. There was no evidence of increased ploidy or increased DNA synthesis associated with hypertrophy after acute or chronic hypoxia exposure. The data suggest that an initial event which could facilitate augmented protein synthesis during hypoxia acclimation appears to be an increased availability of oxygen and/or nutrients brought about by an expansion of the capillary bed and vascular proliferation.

NUCLEAR SEX DIMORPHISM IN THE MONGOLIAN GERBIL

Sectioned material from male and female gerbils, Meriones unguiculatus, was stained with the Biebrich scarlet-fast green FCF procedure for sex chromatin and the Feulgen technique for DNA. There was a significant sex difference among the nuclei of male and female cerebral cortex neurons, kidney cuboidal epithelium, intestinal columnar epithelium, liver parenchymal cells and skeletal muscle nuclei.

THE CYTOLOGY OF INFECTION STRUCTURE DEVELOPMENT IN UREDIOSPORE GERM TUBES OF UROMYCES PHASEOLI VAR. TYPICA (PERS.) WINT.

Urediospores of Uromyces phaseoli var. typica (Pers.) Wint. race 32 Arth. germinated on mineral oil – nitrocellulose membranes and sequentially developed appressoria, vesicles, and infection hyphae. The nuclear behavior during in vitro differentiation of infection structures was studied by use of the Feulgen technique. The two urediospore nuclei divided in the germ tube before the formation of appressorium. This was followed by a second division of the four daughter nuclei in the appressorium, and occasionally by a third division of the eight nuclei in the vesicle and infection hypha. Haustorial mother cells were formed in infection hyphae in vitro and contained from two to five nuclei. In contrast, nuclear division did not occur in germ tubes where growth continued linearly. Infection structures that developed in vitro resembled those produced during infection of the host by urediospores of other species of rust fungi.

Spermatogenesis in the hermaphroditic Digenea (Trematoda)

While some variation of detail may be found in different species of the hermaphroditic Digenea, the process of spermatogenesis conforms to a common plan throughout the group. There is divergence of opinion concerning the interpretation of the structure of the ripe spermatozoon.In the testis of a young animal, primary, secondary and tertiary spermatogonia are present. The tertiary spermatogonia divide to give a group of eight primary spermatocytes that undergo the first division of the meiotic phase to form sixteen secondary spermatocytes. As a result of the second division of the meiotic phase, the sixteen secondary spermatocytes give a group of thirty-two spermatids that through a complicated series of changes are transformed into spermatozoa. During spermateleosis much of the cytoplasm of the late spermatid is sloughed off.Recent research, including the application of the Feulgen technique, the examination of living material, and electron microscopy, supports the view that the ripe spermatozoon is composed of an elongate head, and a flagellum. The head, with the exception of its external sheaths, consists of nuclear material.The flagellum of the sperm of Fasciola hepatica is Feulgen-negative and is composed of a proximal and a distal region. Its proximal part is provided with two axial filaments, a middle fibril and an external sheath. The axial filaments and the middle fibril are continued into the distal region where the external sheath appears to be absent. The external sheath of the flagellum of the sperm of Haematoloechus ( = Ostiolum) medioplexus is said to be composed of thirty-six fibrils. Claims that the flagellum of some digeneans contains a centriole, a middle-piece, and mitochondria have not so far been substantiated by means of electron microscopy.

POPULATION DYNAMICS OF INTESTINAL EPITHELIA IN THE RAT TWO MONTHS AFTER PARTIAL RESECTION OF THE ILEUM

Sprague-Dawley rats that had been subjected 2 months previously to partial resection (10 per cent) of the small intestine and an equal number of control rats were injected with tritiated thymidine and sacrificed at intervals during the subsequent 16 hours. Segments of duodenum, jejunum and ileum were prestained by the Feulgen technique and radioautographed. The proportion of crypt cells bearing labeled nuclei, the percentage of labeled crypt cells in mitosis and the appearance of labeled crypt cells on the villi were determined. Comparison of control and resected rats showed that (a) the proportion of intestinal crypt cells incorporating thymidine was considerably greater and uniformly high throughout the shortened intestine, (b) the life cycle of crypt cells was slightly reduced, and was uniform throughout the shortened intestine, and (c) the time during which cells were retained in crypts was markedly reduced. On the basis of persistent, generalized increase in the production of crypt cells, and on prior evidence that the epithelial cells of shortened intestine continue to have a brief life span and evidence of metabolic immaturity, the existence of a humoral factor, tentatively called "intestinal epithelial growth hormone," is postulated.

DECREASE IN NUCLEAR FEULGEN-POSITIVE MATERIAL (DNA) UPON AGING IN IN VITRO STORAGE OF BOVINE SPERMATOZOA

The Feulgen-DNA content of sperm cells from 5 bulls was studied by means of microspectrophotometry after storage at 5°C for 2, 3, 5, and 10 days in a yolk-citrate diluent permitting slow aerobic metabolism. A subsample of sperm cells from each bull was subjected to the Feulgen technique on each of the storage days selected. The cells sampled on each of these days received a standard 12 minute, 60°C hydrolysis. Absorption measurements at 546 mµof the individual cells indicated a marked progressive decrease in the Feulgen-DNA content of the stored spermatozoa. The loss of 30 per cent of the initial DNA at the end of 5 days' storage was highly significant statistically. This decrease approximately parallels the known decrease in fertility of stored sperm cells, as well as the increase in apparent embryonic mortality resulting from the use of similarly aged spermatozoa for artificial insemination.