[Induction of mouse and rat liver microsomal enzymes by polychlorinated biphenyls and its relations to the PCB levels in the tissue]

Kanechlor (KC)-300, 400, 500, and 600 consisting of polychlorinated biphenyls (PCB) containing 43, 48, 55, and 61% chlorine respectively, were administered in a single dose of 100 mg/kg to mice and rats. The effect of PCB was investigated by determining pentobarbital sleeping time, liver microsomal hemoprotein contents, PCB level and gaschromatography (GC) pattern in tissue. Pentobarbital sleeping time was prolonged 2 to 4 times longer than that of control level after 3 to 4 hr of KC treatment in both ICR and ddN strain mice and KC-300 was the most effective. Forty-eight hr after treatment, however, this sleeping time was half that of the control. Sleeping time in ICR strain mice returned to control level 8 days after the treatment with KC-300 and KC-500, but the decrease in sleeping time continued in ddN mice. Conversely, the prolongation of sleeping time in rats was only 20% the control level at 3 hr after KC-300 treatment, but the shortening of sleeping time was more marked than in mice. Both the prolongation of sleeping time in mice treated with KC-300 and the shortening of sleeping time in rats treated wiht KC-500 were more rapidly effected when an oral dose rather than when a intraperitoneal one was given. Induction of liver microsomal cytochrome P-450 level was maximum in rats treated with KC-600 and increase of hemoprotein level and shortening of sleeping time were proportional to the chlorine content of PCB. The CO-difference spectrum of microsomes from rats treated with KC had an absorbance maximum at 448 nm. Direct relationship between storage of PCB in adipose tissue and the induced effect by KC has also been demonstrated in rats. PCB level in the liver of rats was higher for about 8 hr after KC-500 treatment given orally and was lower than the PCB level in adipose tissue after 8 hr. The GC-pattern of PCB stored in tissues was different from that of standard KC, indicating that all components were not metabolized at the same rate and that the components of the KC with the longer retention time were metabolized to a lesser degree than those with the shorter retention time.

Scanning electron microscopic study on the saccus vasculosus of the rainbow trout

Both free and cracked surfaces of the saccus vasculosus in adult rainbow trout (Salmo gairdneri) have been investigated by scanning electron microscopy (SEM). The saccus vasculosus is the rich-folded epithelium composed of highly specialized coronet cells, supporting cells, and presumable liquor-contact neurons. The coronet cells are characterized by both numerous specialized cilia, so-called "globules" projecting into the saccus lumen and abundant smooth endoplasmic reticulum in the cytoplasm. By the appearance of these globules, coronet cells are roughly divided into two types: botryoidal coronet cells and flower-like. The former is supplied with grape-shaped globules, whose density is 60-80 pieces a cell. The latter contains club- or petal-shaped globules, which number 50-60 pieces a cell. The functional significance of these globules is additionally discussed. The free surface of the supporting cells is relatively smooth, and short microvilli lie scattered on the surface. The cells called liquor-contact neurons (the third type) possess a head-like protrusion where long solitary cilia can be recognized.

Effects of castration and androgen-substitution on the morphology of the epididymal epithelium of the Japanese monkey, Macacus fuscatus, as revealed by scanning electron microscopy

The caput epididymidis from castrated and androgen-supplemented, castrated Japanese monkeys was observed with the scanning electron microscope. The experimental findings were compared with the normal structures in control animals. The epididymal lumen of control animals was lined by a tall, pseudostratified columnar epithelium possessing long, slender stereocilia which were densely arranged in a tuft-like form. After castration, the epididymal epithelium was decreased in height to one-fifth of controls. The stereocilia were also considerably reduced in length and in number, resulting in a flattened epithelial surface with polygonal boundaries. Frequent projection of a long, single cilium from an epithelial cell into the lumen was also a prominent feature in the epididymal ducts of the castrated animals. Administration of testosterone to the castrated animals resulted in almost complete recovery of the epididymal epithelium as well as regeneration of the stereocilia which regained a tuft-like arrangement.

Hypoxia and induced mutations in Syrian (golden) hamsters. The origin and perpetuation of a species

We were able to identify anomalous chromosome patterns-monosomy, trisomy, and polyploidy-in metaphase plates prepared from embryos of Syrian hamsters (Mesocricetus auratus) whose mothers had been exposed to low-pressure hypoxia during the hours after copulation. These females were exposed in a low-pressure chamber for 4 hours at pressures equivalent to 30,000 feet of altitude before (estimated) ovulation to create acid shifts of pH equilibrium in the milieu of newly released eggs during passage of sperm upward, during fertilization itself, and during early cleavage stages. The D group chromosomes were most frequently involved in both monosomy and hyperdiploidy. The easily identifiable X chromosome also appeared to be susceptible to aneuploid formation. Chromosomally abnormal patterns most frequently among sibling embryos conceived by aging mothers exposed to low-pressure hypoxia. The significance of induced mutations is discussed.

Ultrastructural changes of the hypothalamo-hypophysial neurosecretory system in the magnesium deficient rats

A magnesium deficient diet caused transient but marked degenerative changes in the rat hypothalamo-hypophysial neurosecretory system which strongly resembled in many ultrastructural respects those induced by a prolonged administration of aldosterone as previously reported by us. The possible mechanism for this selective alteration in the neurosecretory neurons has been briefly discussed with regard to aldosterone secretion.