Ultrastructural study on experimentally induced ovarian tumors in the rat.

Ovarian tumors induced by intrasplenic ovarian grafting were studied ultrastructurally to obtain the details with particular references to cytoplasmic organelles associated with steroid synthesis. The grafted cells were transformed ultrastructurally at around 7 months following intrasplenic ovarian grafting, in fact, intermediate type of cells were also seen in the grafts at this period. The grafted cells before the transformation showed fine structural evidence of steroid hormone secretions, as indicated by the presence of abundant smooth endoplasmic reticulum, lipid droplets and mitochondria with tubular or vesicular criste. After transformation, the cells, however, had no fine structural features associated with the production of steroid hormones.

Electron-microscopic studies on the maturation of secretory cells in the mouse Harderian gland.

The porphyrins in the Harderian glands of mice are first detectable at 7-8 days of age in both sexes. Thereafter, the levels show a marked rise during the closed-eye period, reaching a peak around the time of eyelid disjunction and then decrease gradually until day 25. At onset of puberty, the level rises again and exhibits a sexual dimorphism. The development of the Harderian gland was examined by light and electron microscopy in the mouse. Although two types of secretory cells, designated as type A and type B, comprise the glandular epithelium in fully developed glands, the time of neonatal appearance is different between the two. Type A cells first appear on the 5th day of age, while type B cells appear around the 7th day corresponding to the time at which porphyrins are first detected. Results of the investigations suggest that the porphyrins in the Harderian gland of mice may be synthesized mainly by type B cells.

Effect of loss of mechanical distension on collagen degradation in the mouse uterus.

In unilaterally pregnant mice, loss of mechanical distension induced by artificial removal of fetuses from the pregnant uterus was followed by oedema in the endometrium. No endometrial oedema was found in the non-pregnant uterine horn, which did not experience the loss of mechanical distension at parturition. Ovariectomy on the last day of pregnancy did not prevent the appearance of endometrial oedema on the day of parturition. These histological results indicate that collagen degradation following the loss of mechanical distension of the uterine wall is attributable to formation of oedema in the endometrium.

Collagen degradation and mucosal mast cell in endometrium of mouse uterus during early postpartum period.

On the morning of the day of parturition, several parts in the endometrium showed edema in which collagen birefringence was not observed, indicating that collagen degradation occurs firstly in the endematous area. Undegradated collagen might be redistributed wholly in the endometrium on postpartum day 1 when the area of endometrium has diminished. The number of mucosal mast cells in the endometrium did not fluctuate in parallel with the endometrial collagen-degrading process, suggesting that mucosal mast cells do not participate in the collagen degradation during the early postpartum period.

Removal of collagen bundles in murine uterus during postpartum involution.

The localization of collagenolytic activity within the tissue compartments of the mouse uterus was investigated during postpartum involution. The rate of collagenase activity was measured by analysis of tissue levels of hydroxyproline from the day of parturition to the 10th postpartum day. Collagen bonding was analyzed by viewing birefringence induced by the picrosirius red-binding technique. An attempt was made to interrelate quantitative analysis with the histologic distribution of collagen during postpartum days 1-10. Histologic and quantitative evidence indicated the following: 1) The collagenous compartments of the endometrium and myometrium differ in their response to the postpartum rise in collagenase activity; collagen degradation occurs primarily in the endometrium, that is, the myometrial collagen remains, but much of the endometrial collagen is removed. 2) Endometrial collagen is degraded particularly in the immediate subluminal compartment.

Elimination of old or worn red blood cells in the senile murine spleen.

After amyloid had deposited in the perifollicular area, cells contained iron disappeared in the red pulp but remained in the lymphoid follicles. Red blood cells must pass a slit of amyloid in the perifollicular area. Red blood cells become mechanically more fragile as they age. Hemoglobin in the serum is not engulfed by splenic macrophages. Disappearance of cells contained iron in the red pulp indicated that old or worn red blood cells are eliminated more by mechanical stress than by phagocytosis of macrophage in the senile spleen having amyloid deposition.

Fine structure of melanocytes and macrophages in the Harderian gland of the mouse.

The presence of dendritic cells containing melanin granules has been demonstrated employing silver impregnation and electron microscopy in the interstitial tissue of the Harderian gland of the mouse. Two types of melanocytes, either with or without the various developmental stages of melanin granules, were found in the gland. Cells with developing granules were more dendritic and contained a large number of cytoplasmic organelles. The other cells were ellipsoidal or slender in shape and contained few cytoplasmic organelles and a large number of fully melanized granules, but no developing granules. In general, the granules of the Harderian gland melanocytes resembled granules from other organs (particularly the skin of the eyelids). The general size range of the granules was 0.2-0.9 micron. Each granule was enclosed by a membrane. The Harderian gland macrophages contained fully pigmented melanin granules of various sizes. The granules were enclosed by a membrane either singly or in groups. Some of the melanin granules within the phagosomes showed signs of degradation, revealing the underlying matrix.

Effects of endocrine glands and hormone replacement on the mast cell count of the Harderian gland of mice.

There are marked sex differences in the Harderian gland of the C3H/He mouse strain, the females having a larger number of mast cells than the males as one of the major differences. Mast cell counts of the Harderian gland were made on male mice subjected to combinations of adrenalectomy, gonadectomy and administration of sex steroid hormones. Castration alone caused a significant increase in the count resulting in about three times the number found in intact males. Castration plus adrenalectomy increased the count over 6-fold, to levels close to those found in female mice. Administration of testosterone or estrone to the mice which had been castrated and adrenalectomized prevented the increase, while progesterone treatment had no effect on the count. Although the number of mast cells in the male Harderian gland was necessarily small compared to either the female gland or that of castrated and adrenalectomized males, no obvious dimorphism could be found microscopically.

Effects of lighting conditions and of hormone replacement on the level of porphyrins in the rat Harderian gland.

The effects of lighting conditions and/or gonadal secretions on the porphyrins of rat Harderian glands were studied. In female rats, exposure to constant light (= LL) induced a 50% decrease of porphyrin in the Harderian gland. Ovariectomy in these animals caused an increase to levels comparable to those found in intact controls. In males, exposure to constant darkness (= DD) produced a marked increase in the glandular porphyrins together with greatly decreased weights of accessory sexual organs. Further, orchidectomy remarkably increased porphyrin levels in rats kept under conditions of LL or DD. Administration of testosterone propionate to castrated male rats significantly decreased the porphyrin contents in the gland, although estradiol benzoate and progesterone treatments had no effect on the levels. Similar results were obtained in female rats.

Collagen concentration and mast cell in perinatal murine uterus.

Edema was found in the uterine tissue on the day of parturition. The number of mast cells was increased significantly on this day, indicating that the time of appearance of the edema is identical to the time of a significant increase in the number of mast cells. These results suggest that mast cells induce the high vascular permeability that permits passage of collagenase-activating proteases to the uterine tissue from the serum.

Hydroxyproline concentration in soluble and insoluble material from serum treated with trichloroacetic acid in postpartum mice.

The hydroxyproline concentration in both the soluble and insoluble material from trichloroacetic acid-treated serum from postpartum mice was determined. The hydroxyproline concentration in the insoluble material increased, but that in the soluble material did not increase during the uterine involuting period.

Ultrastructural evidence for estradiol synthesis in the ovary of persistent-estrous rats exposed to continuous illumination.

The relation between sex hormone levels in blood and ultrastructural changes of ovarian follicles was examined in persistent-estrous rats exposed to continuous illumination (LL) for 100 days. Plasma LH showed a tonic level secretory pattern, and circulating estradiol and estrone concentrations were relatively high, while both levels of FSH and progesterone were low. Various stages of growing and degenerating follicles were observed in the ovary of the LL-exposed rats. The early stage of antral follicle did not seem to possess the ability of steroidogenesis. Theca cells around mature antral follicles contained prominent Golgi apparatuses, plenty of smooth endoplasmic reticulum (ER), abundant free ribosomes and many round-mitochondria. A few newly formed lipid droplets were seen in some of theca cells. Granulosa cells contained much distended rough ER, well-developed mitochondria, several lipid droplets and microfilaments. The theca cells of abnormal follicles with hyperplastic and infolded layers of granulosa cells contained many lipid droplets. However, the development of the smooth ER became hindered with increasing lipid droplets in the theca cell. On the other hand, granulosa cells of abnormal follicles contained greater numbers of lipid droplets than those of antral mature follicles, and were equipped with well-developed cytoplasmic organelles as were those of mature antral follicles. Theca interna cells of abnormal follicles may be more involved in the secretion of androgen, which has already been accumulated in the lipid droplets, than the cells involved in the active synthesis of the hormone, while the granulosa cells may convert its androgen to estrogen. The present findings suggest that both follicles of mature and abnormal types in the LL-exposed rat retain enough capacity of estradiol production and participate in the continued elevation of circulating estradiol, probably resulting in the stimulation of the theca cells by the tonic level of LH and of the granulosa cells by the levels of FSH, which are lower than the basal values during the normal 4-day estrous cycle.

Intraocular 6-hydroxydopamine prevents the persistent estrus induced by continuous light.

Following the intraocular injection of 6-hydroxydopamine, which can destroy the retinal dopaminergic neurons, female rats showed a normal estrous cycle in LD 12:12 but not a persistent estrus in continuous light.

Correlation between number of placental detachments and amount of postpartum uterine involution in mice.

Both the uterine weight and total hydroxyproline content augumented in parallel with the number of placental scars on the day of parturition. In the uterus having any number of placental scars, the time of half loss of the organ weight and the total hydroxyproline content, respectively, was the same. These results suggested the amount of postpartum involution increases as the number of placental detachment becomes high.

Constant number of immunogloblin G positive plasma cells around the penicilli in murine spleen with increasing age.

The splenic lymphoid tissue of mice reared in a conventional environment regressed with increasing age. Immunogloblin G positive plasma cells gathered along the penicilli in the senile spleen as well as in the adult control spleen. The number of plasma cells around the penicilli showed no difference in the senile spleen as compared to the adult spleen. Since mature plasma cells remain in the lymph node for a short time only and seldom divide there, our results indicate that the transformation from B lymphocyte to plasma cell is not affected by age.

Effect of ethylenediaminetetraacetic acid on postpartum collagen degradation: collagen-bound collagenase.

Collagenase occurs in animal tissues in at least two molecular forms; free enzyme and collagen-bound enzyme. This study was undertaken to investigate which form is principal during the postpartum collagen degradation. Ethylenediaminetetraacetic acid, which depresses the calcium concentration in the serum, did not affect the postpartum collagen degradation. Histological study shows that the serum containing inhibitor such as alpha 2-macroglobulin was widely scattered within the endometrium on the day of parturition. Since the calcium is necessary for collagenase to bind collagen and that the collagen-bound collagenase together with or without alpha 1-macroglobulin is activated to a same level by protease, these results suggested the principal molecular form of collagenase during the postpartum involution is collagen-bound enzyme.