Luteal cell structure and function were studied by electron microscopy in conjunction with measurement of progesterone production by corpora lutea which were isolated and incubated in vitro on successive days of the fourday hamster estrous cycle. Granulosal cells were primarily responsible for the formation of the corpus luteum. Agranular endoplasmic reticulum and lipid droplets developed during luteinization of granulosal cells on the first post-ovulation day (day 1). Luted cell hypertrophy on day 2 resulted from dilation of tubular agranular endoplasmic reticulum and swelling of mitochondria with tubular cristae. Plasma progesterone levels on the first two days of the cycle appeared to be correlated with luteal activity as corpora lutea were demonstrated to synthesize progesterone during this interval. Luteolysis occurred on day 3 with a reduction in luteal cell size accompanied by condensation of the agranular endoplasmic reticulum, regressive changes in the mitochondria, and a marked drop in luteal progesterone synthetic activity. On day 4, extensive phagocytic activity and luteal cell autolysis indicated an advanced involutional state. The short but functional luteal phase in the cyclic hamster does not appear to involve the production of 20a-hydroxy-pregn-4-en-3-one as occurs in the rat. This progestin was not detectable in plasma or luteal tissue before or after incubation at any time during the cycle. Possible mechanisms regulating luteal cell development and regression during the estrous cycle are discussed.The fine structure of the corpus luteum has been examined in a variety of animals including rat, mouse, mink, rabbit, armadillo, pig, sheep, and human (Christensen and Gillim, '69). Ultrastructural changes in the luteal cell during the reproductive cycle have been described primarily in species having a relatively long cycle with functional corpora lutea. In the rat, mouse and hamster, the short estrous cycle is not considered to have a functional luteal phase until pseudopregnancy or pregnancy is induced by the mating stimulus (Greenwald and Rothchild, '68).Studies using the cyclic mouse or rat are complicated by the retention of several sets of corpora lutea from previous cycles. However, the golden hamster has a regular four-day estrous cycle, and there is rapid development and regression of corpora lutea during a single cycle (Grady and Greenwald, '68; Kent, '68). Progesterone levels in the cyclic hamster exhibit a biphasic pattern with a clearly defined peak AM. J. ANAT., 136: 235-250. during the preovulatory period and another peak on the second day following ovulation (Leavitt and Blaha, '70; Lukaszewska and Greenwald, '70). The presence of intense 3p-hydroxysteroid dehydrogenase activity in hamster corpora lutea on the second postovulatory day suggests the plasma progesterone observed at this stage may be luteal in origin (Blaha and Leavitt, '70). The present study was designed to provide definitive information on the structure and function of the corpus luteum during the hamster ...
Hypertrophic scar tissue has been observed to soften and thin following Z plasty without removal of any of the scar tissue. Histochemical studies of tissue before and after Z plasty showed that abnormally sulfated mucopolysaccharides were replaced by normal acid mucopolysaccahrides within 14 days. Collagen in hypertrophic scar appeared in nodules and fibers perpendicular to the surface of the skin rather than as long straight fibers parallel to the skin surface as normally seen. Elastic fibers were reduced and scar was relatively avascular. Following Z plasty the amount of collagen decreased and fibers were oriented in bundles at right angles to each other, parallel to the surface. When tissue was examined by electron microscopy collagen fibers showed marked variation in diameter. Microfibrils were increased and there were aggregates of fibrils with periodicity of 1500 to 1600 A. Following Z plasty, areas which previously contained only microfibrils now had unit collagen fibers with normal periodicity. Urinary excretions of hydroxyproline and hydroxylysine, amino acids found only in collagen, were increased following Z plasty, coinciding with the softening of the scar. Excretion of the disaccharide, glucosylgalactosylhydroxylysine, predominantly found in skin, increased following Z plasty, while excretion of the monosaccharide, galactosyl-hydroxylysine, predominant in bone collagen, remained constant. Amino acid composition of collagen, remained constant. Amino acid composition of collagen isolated from hypertrophic scars was similar to that present in skin and tendon, and unlike that in cartilage or infant dermis. Hydroxyproline content was slightly decreased and hydroxylysine content slightly increased compared to skin or tendon. Histochemical, ultrastructural and biochemical studies of the same specimens suggested that collagen with disordered fibril formation was present in the hypertrophic scar and was degraded following Z plasty. Changes in the molecule which occurred after synthesis of the protein core might be responsible both for the failure of normal maturation of the scar and for its sensitivity to degradative enzymes following Z plasty.
MoIphometric analyses of liver parenchymal cells were performed on male albino rats fed a semipurified diet supplemented with two levels of copper and zinc. These metals were administered in demineralized drinking water to four groups of animals at two levels. ( 1 ) 0.25 pgm Cu/ml, 2.5 pgm Zn/ml, and ( 2 ) 1.0 pgm Cu/ml, 10 p g m Zn/ml. Cadmium, also administered in the drinking water daily to rats at 17.2 pgm cadmium/ml, was given to one group of animals on each of the two semipurified diets. Two groups of rats were given laboratory chow plus 17.2 pgm Cd/ml for 71 days and for 280 days.Volume densities of all organelles diminished significantly when levels of copper and zinc were lowest. Surface densities of rough and smooth endoplasmic reticulum were significantly decreased.Higher levels of copper and zinc produced morphologic and morphometric parameters which fell just below those obtained for rats fed chow. Glycogen accumulation was highest when the levels of metal were low. Lipid inclusions were more frequent with semipurified diets than with chow.Hepatocytes from rats fed the semipurified diet with low copper and zinc plus cadmium demonstrated a significant increase in smooth endoplasmic reticulum compared to animals fed the semipurified diet alone. The smooth endoplasmic reticulum changed little when cadmium was given to rats receiving adequate copper and zinc. Smooth endoplasmic reticulum increased when diets included chow and cadmium whereas rough endoplasmic reticulum decreased.Cup-shaped and elongated mitochondria with longitudinal cristae appeared in hepatocytes from animals fed chow with cadmium. These were not seen with semipurified diets and cadmium. different housing conditions, cleaning routines, in normal diurnal cycles and with pregnancy and lactation (Hope, '70, Vesell et al., '73, Chedid and Nair, '72).In this study we proposed to determine the morphometric patterns occurring in hepatocytes of rats fed semipurified diets containing low and adequate levels of zinc and copper in comparison with those fed a standard commercial diet and to monitor the subcellular changes in these patterns due to concurrent administration of the toxic metal cadmium. This would allow us to determine the effect cadmium would have on the liver cells of animals receiving only suboptimal and optimal amounts 1This work was supported by USPHS grants ES-2 To whom requests for reprints should be sent. 00127, ES-00159 and OH-00337. 23
Young adult female rats were perfused with buffered aldehydes. Selected tissues were prepared for light microscopy by standard techniques. The only procedural modifications permitted were those required by the special physical and chemical characteristics of the tissue. Extreme brittleness called for special precautions in all manipulative steps from excision to final embedment. Turbulence during the early stages of dehydration was lessened by drop-by-drop addition of the next concentration of ethanol. High melting-point paraffins and celloidin-paraffin embedments were used to accommodate the hardness of the tissues and to prevent disarrangement during mounting. Steel knives specially sharpened with fine abrasives on plate glass were fitted with fluid reservoirs. Four micron sections were obtained routinely. Sections were transferred individually from the reservoir to glass slides. The common dyes used in light micoscopy tended to overstain these tissues. This tendency was overcome by using shorter exposure times, lower concentrations and blocking agents. T h e chromatic staining techniques familiar to histologists and pathologists were useful after minor modifications.
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