The ultrastructure of the pars distalis of the hypophysis in males of Triturus cristatus carnifex Laur., treated with the antiandrogen cyproterone acetate

Natural and estrogen-induced sexual dimorphisms in the pituitary of the newt Pleurodeles waltlii Michah and of the common frog Rana temporaria L

In the female newt, Pleurodeles waltlii, the somatotropic cells of the adenohypophysis are characterized by large, electron-dense inclusions (1-6 micron). Inclusions were also found in adult male newts after treatment with 17-beta-estradiol (5 mg/liter of aquarium water, for 10 days to 4 months). The ultrastructural genesis of these inclusions is described for treated males and for females during sexual maturation. In both cases, the same morphological features (dimensions, and filamentous and crystalloid arrangements) have been observed. The origin of the inclusions is discussed with respect to estrogens. The effects of 17-beta-estradiol are also studied in gonadotropic pituitary cells (GTH cells) of the male frog (Rana temporaria) after injections ranging over 6 to 8 weeks (0.05 or 0.5 mg/0.1 cc PPG) every 4 days. In GTH cells, aggregates of tubules are present in large inclusions. Such aggregates are observed in GTH cells in the female frog 8 to 10 weeks after breeding. The aggregates are thought to be involved in the process of intracellular regulation of hormone secretion, since such structures appear when there is a high level of circulating estrogens.

Effect of cyproterone acetate on adenohypophysis of castrated mice

Pituitaries from castrated male mice injected with cyproterone acetate were examined ultrastructurally. LH gonadotrophs showed two types: (a) those containing a dilated RER, a hypertrophied Golgi, and decreased granular content; and (b) those presenting an electron lucent cytoplasm and a nonhypertrophied RER. Following cyproterone acetate treatment both LH cell types showed increased RER cisternal hypertrophy and absence of Golgi membranes. In LH type (a) gonadotroph-increased granular content was noted. No detectable alterations were noted in FSH gonadotrophs following cyproterone acetate treatment. Cyproterone acetate may have stimulated the synthesis of the protein component but inhibited the incorporation of the carbohydrate moiety and LH release.

Effects of an antiandrogen, cyproterone acetate, on the kidney of the three-spined stickleback (Gasterosteus aculeatus L.)

The fine structure of the kidney is studied in the sexually mature male three-spined stickleback after administration of an antiandrogen, cyproterone acetate. Under these conditions, the dedifferentiation of renal tubules is characterized by the same involutive processes as those induced by castration, with the difference that cyproterone acetate only begins to act after 14 days whereas after castration the first signs of involution are visible after 7 days. The ultrastructural modifications affect the nucleoli, the rough endoplasmic reticulum and the Golgi apparatus. They reflect an inhibition of the secretory process. The results obtained demonstrate that administration of cyproterone acetate to male sticklebacks has an inhibitory effect on renal target cells, apparently indistinguishable from the changes induced by lack of male sex hormone, and that this drug may be a valid substitute for castration in fish.

The ocellus of the cockroach, Periplaneta americana (Blattariae): receptory area

The ocelli of Periplaneta americana were studied by light and electron microscopy. The view that the ocellus of the cockroach represents a degenerated structure can no longer be supported. All organelles necessary for function are present. The club-shaped retinular cells lie homogeneously distributed in the cupule of the ocellus. Rhabdoms are seen as sickle-, y-, x- or star-shaped structures with up to six cells in formation. Cells were found which had formed two rhabdomeres. The mass of cell organelles lies in the cytoplasm between the cell nucleus and the rhabdom. Smooth endoplasmic reticulum is wound into a spindle formation of considerable size at the origin of the axon in some cells. A cylindrical body in which 10-40 microtubules are packed, as yet unknown in insect retinular cells, is described. The receptory area of the ocellus terminates in a tapetum which contains granules, soluble in alcohol. The axon bundles of the retinular cells run through the tapetum and immediately thereafter make synaptic contact with dendrites of the ocellar nerve cells, while still within the ocellus.