Edward G. Rennels

Primary site of gene action in anterior pituitary dwarf mice.

The transplantation of anterior pituitary glands of normal mice into hypophysectomized dwarf littermates has resulted in mice that are normal in appearance and growth rate. In contrast, the anterior pituitary gland of dwarf animals, when placed in the sella of hypophysectomized normal littermates, failed to promote the growth of these animals. These results indicate that the primary site of gene action in dwarfism lies in the anterior pituitary itself rather than in the hypothalamus.

Two tinctorial types of gonadotrophic cells in the rat hypophysis

SummaryA modified PAS-methyl blue staining method is described which, in conjunction with aldehyde fuchsin, enables the tinctorial differentiation of two types of gonadotrophs in the pituitary gland of the rat. That these two cell types are both gonadotrophic in function is indicated by their development into distinct PAS-red and PAS-purple castration cells following gonadectomy. In addition to these two kinds of castration cells, thyroidectomy cells which are PAS-negative, aldehyde fuchsin-negative, and have an affinity for orange G are seen in the pituitary glands of animals that have been both gonadectomized and thyroidectomized. Thus, in such glands the three types of modified basophiles are tinctorially different. Differences in the distribution of the PAS-red and PAS-purple gonadotrophs are characteristic of the glands of normal animals. Following gonadectomy, however, extensive shifts in the distribution of these cells occur so that the normal pattern is soon lost.

Morphological changes in prolactin cells of male rats after testosterone administration.

Intact and castrated 25- and 60-day-old male rats were given 200 mug of testosterone propionate (TP) daily for 15 consecutive days. The morphology of the prolactin (PRL) cells was examined by electron microscopy and analyzed by the point counting method of Weibel and Bolender (23). The PRL cells in the controls had long cytoplasmic processes that coursed between adjacent parenchymal cells. The Golgi complex was relatively small in these cells and the area occupied by the secretory granules was, in general, less than in the TP-treated animals. After TP administration, the cells became more ovoid and the Golgi complex enlarged, displaying dilated cisternae and many immature secretory granules. In addition, the diameter of the secretory granules was greater in the animals given the steroid. When the morphology of the PRL cells in the sexually immature control rats was compared to that observed in the older, sexually mature rats, relatively few differences were observed indicating that the response to TP was essentially the same in animals of both age groups. The concentration of PRL was measured in the serum and pituitary gland by radioimmunoassay. There was a significant elevation in PRL in both the serum and pituitary glands of all animals given TP. In contrast, castration led to a fall in PRL levels. From these observations and from the morphological data it can be concluded that TP is capable of stimulating the rate of PRL synthesis and release, and that testosterone may have a regulatory role in PRL biosynthesis and turnover in the male rat.

Evidence on the cellular source of luteotrophin derived from a study of rat pituitary autografts.

SummaryPituitary autografts placed under the renal capsule of adult female rats in estrus were found to produce luteotrophin. Indirect evidence indicates that autografts in male and female rats which were operated on at puberty probably produce this hormone also. Studies on both the adult and “pubertal” animals indicate that pituitary autografts produce the other anterior lobe hormones either at a very low level or not at all.The predominant chromophilic cell type in grafts known to be producing luteotrophin is an elongated acidophile staining selectively with orange G when the “azan” stain is used. Two types of acidophiles were found in the intact rat pituitary, one staining with azocarmine and the other with orange G. The latter has the same morphology as the predominant cell type in active autografts and is considered to be the source of luteotrophin in the rat.

Gonadotrophic cells of the rat hypophysis and their relation to hormone production.

SummaryThe results of these experiments clearly indicate that the PAS-red and PAS-purple gonadotrophs of the rat anterior hypophysis are functionally as well as tinctorially distinct cell types. The PAS-red cells located peripherally in control animals (“peripheral gonadotrophs” of Purves and Griesbach) produce LH. Following castration they begin to appear in greater numbers in the central areas and by 45 days following castration they are predominant in both central and peripheral portions of the glands. At this time after castration the gonadotrophic content of the pituitary gland is predominantly luteinizing in character.The PAS-purple cells which are found in the central portions of control glands (“central gonadotrophs” of Purves and Griesbach) produce FSH. They appear peripherally following castration and are the predominant type of gonadotrophic cell in the glands of short term (10-day) castrates. The gonadotrophic content of such glands is chiefly FSH as shown by bioassay.By 45 days after castration the LH producing “peripheral gonadotrophs” and the FSH producing “central gonadotrophs” have lost their characteristic distribution patterns. Obviously, then, these two gonadotrophic types cannot be accurately followed on the basis of a restricted regional location in the pituitary but must be differentiated on the basis of specific cytological features and staining characteristics.

Histochemical changes in succinic dehydrogenase activity in rat kidney following administration of mercurial diuretics.

Summary and Conclusions Mercuhydrin, when administered to rats by subcutaneous injection causes a marked depression of succinic dehydrogenase activity in the proximal convoluted portion of the kidney tubules, while other portions of the nephron are little affected. This enzymatic inhibition is concomitant with the known time of diuresis and both can be prevented by the administration of BAL. This suggests that the enzymatic inhibition is, in fact, related to the diuresis. This places the locus of mercurial action on the proximal convoluted tubule-most certainly as regards its inhibition of succinic dehydrogenase activity and by implication also its diuretic action

Response of preputial and adrenal glands of the rat to sex hormones.

Summary and Conclusions The administration of estrogen to intact male rats for 40 days induces hypertrophy of their adrenal glands but has the reverse effect on their preputial glands. The latter effect is undoubtedly a result of the virtual cessation of endogenous androgen production. Alterations in the ascorbic acid content of these glands appear to be a reflection of the marked changes in their weight. Androgen treatment for the same period produces a slight but significant increase in the weight of the adrenal glands and a 2-fold increase in preputial gland weight. This effect on the preputial glands is predominantly a direct one, as it is seen also in hypophysectomized animals. In contrast, no direct action of androgen on the weight of the adrenal glands of hypophysectomized rats was observed. It was found that androgen administration reduces the resting level of ascorbic acid in the adrenal and preputial glands of both intact and hypophysectomized rats. Furthermore, this hormone somehow destroys the responsiveness of the preputial glands to the ascorbic acid-depleting action of a single injection of ACTH.

Effects of pituitary removal or transplantation on ovarian ascorbic acid depletion in the rat.

Summary Immature female rats were made pseudopregnant in the manner prescribed for the Parlow LH assay. Hypophysectomy of such animals on the sixth day of pseudopregnancy caused a gradual decline in ovarian weight over a 5-week period but concentration of ovarian ascorbic acid was well maintained. At periods of a week or more after hypophysectomy intravenous injection of LH produced no decline in ovarian ascorbic acid. In other animals the pituitary gland was autografted to the renal capsule on sixth day of pseudopregnancy. Ovarian weight was well maintained in these animals for 4 weeks although at 4 weeks there was a significant decrease in level of ovarian ascorbic acid. Intravenous injection of LH in pituitary graft-bearing rats led to depletion of ovarian ascorbic acid even greater than that found in intact, pseudopregnant rats. It is suggested that animals bearing pituitary autografts should prove valuable in the search for LH releasing factors.

Sialic Acid Concentrations in the Pituitary Glands of Normal and Ovariectomized Rats

The concentration of sialic acid in the anterior pituitary gland of young female rats is approximately 250 micromoles per 100 grams. After ovariectomy there is a marked and persistent rise in pituitary sialic acid; this increase is probably related to the known increase in the production of gonadotrophic hormones.