Effects of heat on the centrosomes of Chinese hamster ovary cells.

Chinese hamster ovary cells were heated either at 45.5 degrees for 15 min or at 42 degrees for 1 hr and then were either fixed immediately or allowed to recover at 37 degrees for intervals of up to 12 hr. In addition control cells and cells heated at 45.5 degrees for 15 min were immediately subjected to a cell fractionation procedure that yielded partially purified centrosome preparations. In 100% of the cells fixed and examined immediately after heating, the centrosomes were damaged. The osmiophilic cloud increased in density and became aggregated. The majority of the pericentriolar particles or virus-like particles disappeared, and in some cases the tubules of the wall of the centriole appeared disrupted. These changes were also noted in the much more abundant population of centrosomes in the partially purified cell fraction. Furthermore, in those cells heated at 45.5 degrees for 15 min, no recovery of the centrosomes or return of virus-like particles occurred even after incubation at 37 degrees for 12 hr.

Development of the implantation chamber in the pregnant bitch.

Uteri taken from 25 bitches at various times during the early stages of pregnancy were studies cytologically to determine how the implantation chamber developed and how fetal-maternal relations were established. On day 13 after the end of estrus, knobs of trophoblastic syncytium formed and became wedged between cells of the uterine luminal epithelium. The syncytium quickly spread along the uterine lumen and into the mouths of the glands, dislodging and surrounding maternal cells. As invasion continued trophoblastic villi, consisting of cores of cytotrophoblast covered by a continuous layer of syncytium, penetrated deeper into the endometrium. The syncytium spread to surround maternal vessels and decidual cells. By day 26 the trophoblast had extended down to the large lacunae. Here syncytial trophoblast covering tips of the villi degenerated, leaving cytotrophoblast exposed to the necrotic zone. These cells possessed characteristics of absorbing cells. Hematomas were formed by focal necrosis of fetal and endometrial tissue at the poles of the implantation sites. Large pools of extravasated blood accumulated and red blood cells were phagocytized by surrounding trophoblastic cells. Therefore, the endotheliochorial relationship in the canine placenta appeared to be established by syncytial trophoblast invading a cellular endometrium. In the necrotic zone and hematomas, cellular trophoblast may have lost its syncytial covering, but elsewhere maternal vessels and decidual cells in the placenta were in direct contact only with syncytial trophoblast.

Development of the endometrium during the estrous cycle in the bitch.

The endometrium of 40 cycling bitches was studied using cytological, cytochemical, and morphometric techniques. Two principal phases of growth and differentiation can be discerned. Phase one begins at the end of anestrus as serum estrogen levels begin to rise and is completed just prior to estrus. It is characterized by growth of the crypts and differentiation of the glandular epithelial cells into well-developed, mucus-secreting cells. Growth, initially rapid, gradually slows. The second growth phase does not begin until the middle of estrus as serum progestin levels rise and lasts nearly a week. Both hypertrophy and hyperplasia of the glandular epithelium and growth of the basal glands characterize this stage. The gland cells develop many well-defined characteristics of absorptive and secretory cells. Another phase of growth occurs in pregnant animals at the onset of implantation. During the third week of metestrus in non-pregnant bitches, the uterus begins to involute. Acid phosphatase and the number of lysosomes increase dramatically in the epithelial cells particularly in the basal glands. Cells lining the lumen and crypts accumulate numerous large lipid droplets. The data are discussed in relation to the clear separation of two distinct uterine functions: (1) sperm transport and maintenance and (2) production and secretion of nutritive uterine milk. Extended periods of follicular development, breeding, and preimplantation in the bitch probably impose this separation.

Estrogen-induced differentiation of the oviductal epithelium in prepubertal dogs.

PIP: 24 prepubertal 6-8 week old Beagle dogs were injected intramuscularly every other day either with 150 mcg/kg estradiol-beta valerate (14), or progesterone respositol (5), or used as controls (5) to determine what effect estrogen and progesterone had on cytodifferentiation. Light and electron micrographs of the oviductal epithelium of the ampullae of the controls and hormone-treated dogs were studied. The epithelial cells in the controls were uniformly low cuboidal with a high nucleocytoplasmic ratio. After 36 hours of estradiol treatment there was nuclear and nucleolar hypertrophy; an increase in the numbers of cytoplasmic polyribosomes and numerous mitotic figues were apparent. Ciliogenesis began and 2 cell types were distinguishable after 3 days of estradiol treatment. Basal bodies in various stages of formation were randomly distributed throughout the apex of many cells. In others, more mature basal bodies were aligned at the apical border or cilia were evident. 6 days of estradiol resulted in complete ciliation of approximately 60% of all epithelial cells. The remaining cells possessed abundant cisternae of rough endoplasmic reticulum (RER) and appeared to be differentiating into mucus-secreting cells. After 10 days, these cells possessed a large Golgi apparatus, large dilated cisternae of RER, and abundant periodic-acid-Schiff positive granules at their apex. Progesterone treatment alone produced no hypertrophy of the oviductal epithelium. In fact, cytomorphometric measurements indicate that progesterone had an opposite effect, causing atrophy (p less than.05) and increasing the nucleocytoplasmic ratio. It is concluded that estrogen alone was capable of producing complete cytodifferentiation in the oviduct of the prepubertal dog.^ieng