Time-dependent effects of lead on rat reproductive functions.

The effects of exposure to lead on endocrine function and the reproductive parameters were studied in pubertal rats treated with 1.0 g l-1 lead acetate in drinking water for 20 days (subacute group) or 9 months (chronic group) in addition to i.v. injections of lead acetate (0.1 mg 100 g-1 body wt.) every 10 (subacute group) or 15 days (chronic group). Although basal levels of testosterone were higher both in plasma and in testes of acutely intoxicated animals, the circulating levels of luteinizing hormone (LH) were not affected in either group, nor was the LH-releasing hormone content of the median eminence. The density of [125I]LH/human chorionic gonadotrophin (hCG) binding sites in testicular homogenates was reduced by saturnism in both groups, concomitant with a significantly increased apparent affinity constant of the hormone-receptor complex. These data can be viewed as the result of a mixture of specific lead toxicity (e.g. at the enzyme level) with other more general actions (e.g. at the level of the hypothalamus-pituitary-testicular axis).

Pharmacological reactivity of rat vas deferens in chronic and subacute lead intoxication.

The influence of subacute and chronic lead intoxication on the responsiveness of the rat was deferens was investigated by determining pD2 and relative responsiveness ratio (p) values for noradrenaline and for acetylcholine. Thus, the pD2 values of noradrenaline and acetylcholine from vas deferens of lead-treated rats were greater than those from normal rats, indicating that lead, in the dose and periods of treatment utilized, provoked a rise in vas deferens sensibility to noradrenaline and acetylcholine. Since it is known that the chirurgical or chemical denervation of the sexual ducts also provokes hypersensitivity, it may be suggested that this would be a possible mechanism for the observed alterations. A local lead toxic effect on the smooth muscle or at the level of androgen receptors should also be considered.

Saturnism in the male rat: endocrine effects.

The effect of exposure to lead on endocrine function was studied in pubertal rats treated with 1.0 g/l lead acetate (PbAc) in drinking water for 20 days (subacute group) or 9 months (chronic group) in addition to iv injections of PbAc (0.1 mg/100 g body weight) every 10 (subacute group) or 15 days (chronic group). Although basal levels of testosterone were higher both in the plasma and in the testes of acutely intoxicated animals, the circulating levels of luteinizing hormone (LH) were not affected in either group, nor was the LHRH content of the median eminence. The density of [125I]LH/hCG binding sites in testicular homogenates was reduced by saturnism in both groups. However, the apparent affinity constant of the hormone-receptor complex significantly increased. These data can be viewed as the result of a mixture of specific lead toxicity (e.g., at the enzyme level) with other more general actions (e.g., at the level of the hypothalamus-pituitary-testicular axis).

Saturnism in the male rat: endocrine effects

The effect of exposure to lead on endocrine function was studied in pubertal rats treated with 1.0 g/l lead acetate (PbAc) in drinkin water for 20 days (subacute group) or 9 months (chronic group) in addition to iv injections of PbAc (0.1mg/100g body weight) every 10(subacute group) or 15 days (chronic group). Although basal levels of testosterone were higher both in the plasma and in the testes of acuctely intoxicated animals, the ciruclating levels of lutinizing hormone (LH) were not affected in either group, nor was the LHRH content of the median eminence. The density of [125I]LH/hCG biding sites in testicular homogenates was reduced by saturnism in both groups. Howeverm the apparent affinity constant of the hormone-receptor complex significantly increased. These data can be viewed as the result of a mixture of specific lead toxicity (e.g., at the enzyme level) with other more general actions (e.g., at the level of the hypothalamus-pituitary-testicular axis)

Pattern of acquisition of rotavirus antibody in children followed up from birth to the age of three years.

Nine hundred and forty-eight serum samples from 83 children living in Belem, Brazil, collected within their first three years of life, were tested for the presence of group-specific rotavirus-antibody by an enzyme-linked immunosorbent assay (ELISA) blocking-test. Passively transferred maternal antibody lasted about two and half months; subsequently, low levels of rotavirus antibody started to appear at seven months, reaching a peak at eleven months of age. From one year onwards positivity gradually increased, reaching highest values at 34 months of life. Individual responses were examined in sera from 61 children who were followed up since birth to three years of age: 38 (62.3%) of them developed a long-term immunity following first infection; eleven (18.0%) children developed a short-term immunity after first infection by rotavirus; seven (11.5%) had no antibody response within their first three years of life; and 5 (8.2%) showed positive antibody response from birth to three years old.

The fine structure of the swine sweat gland. II. The coiled ducts.

The duct of the swine sweat gland crosses the dermis and epidermis in sequence. The cells of the dermic segment seem to be related with cellular secretion and absorption. In the epidermic segment of the duct the whole morphology of the cells resembles the cellular morphology of the epidermic cells.

The fine structure of the swine sweat gland. I. The acini.

The structure of the acini in the swine sweat gland is described here at the TEM level. The acini of the sweat gland in the pig is formed by 2 secretory cell types: dark seromucous cells and clear cells. The dark seromucous cells are actively secretory and their secretion is apocrine. The clear cells seem to be involved in an active transport of water and electrolytes through their cytoplasms.

Fine structure of the interstitium of the epididymis of the South American Opossum (Didelphis azarae, Marsupialia).

The interstitial space of the ductus epididymidis of the opossum (D. azarae), contains fibers and cell elements of the connective tissue, smooth muscle cells and amyelinic nerve fibers. This structure, studied through TEM, is similar to the fine structure of the interstitium of the epididymis in rodents. However, the normal occurrence of mast cells in the interstitial space of the ductus epididymidis in opossum, seems to be a peculiar morphological characteristic of this species.

Fine structure of principal and basal cells of the cauda epididymidis of the South American opossum (Didelphis azarae).

The aim of the study was to investigate cytological characteristics of principal and basal cells, at the ultrastructural level, in the cauda epididymidis of the opossum. Adult sexually mature opossums were used. Signs of pinocytosis and absorption and secretion were seen in both cells. These functions and the fine structure of the principal and basal cells of this marsupial are discussed comparatively with the fine structure of these cells in the epididymidis of eutherian mammals.

Ocorrência de células principais ricas em muco-substâncias neutras no epidídimo de bovino azebuado / Ocurrence of principal cells rich in neutral mucosubstances from the epididymal duct of zebu cattle

Os autores realizaram estudo morfológico e histoquímico de células principais ricas em muco substâncias neutras que ocorrem no segmento inicial do epidídimo de bovino azebuado. Esta observaçäo parece se relacionar com secreçäo de glicogênio e glicoproteínas, glicólise anaeróbica e maturaçäo dos espermatozóides que ocorrem neste segmento

Subcellular structure of the luminal content of the cauda epididymidis of the opossum (Didelphis azarae).

The luminal content of the cauda epididymidis of the opossum has been studied by transmission electron microscopy. The content is represented by single and paired spermatozoa. Subcellular features of both spermatozoa and their cytological components have been described on the basis of the morphology of spermatozoa in the epididymis of other metatherian forms.

[Regional histology of the epididymis in the South American opossum. Light microscope study]. / Histologie Régionale de l'épididyme chez l'opossum sud américain. Etude de microscopie optique.

The opossum epididymis was subdivided into 7 histologically distinct zones. 2 zones are localized into the head (initial segment or zone I and zone II); 3 zones into the body (zones III, IV and V), and 2 zones into the tail (zones VI and VII). It was found that each zone could be readily distinguished on the basis of its histological and cytological features at optical microscopic level and primarily on the basis of the morphological appearance of the principle cells.

Effect of insulin on vaginal epithelium cells from castrated female rats. II. Studies on exfolative cytology.

The effect of insulin (single subcutaneous injection, 3 IU/100 g body weight) on the vaginal epithelium cells of female adult castrated rats was studied. An increase in nuclear volume and modification of the cytological picture suggesting an activation of cellular metabolism were observed. This anabolic effect of insulin is observed in other cells of the organism, and is not confined to vaginal epithelium cells.