Histological and histochemical study of the uropygial gland of chimango caracara (Milvago chimango vieillot, 1816).

The uropygial glands of birds are sebaceous organs that contribute to the water-repellent properties of the feather coat. We studied the histological and histochemical characteristics of the uropygial gland of chimango caracara using hematoxylin and eosin (H & E), Gomori´s trichrome, orcein, Gomori´s reticulin, periodic acid-Schiff (PAS), Alcian blue (AB) and a variety of lectins. The gland is composed of two lobes and a papilla with 20 downy feathers. It is surrounded by a capsule of dense connective tissue that contains elastic, reticular and smooth muscle fibers. The papilla is delicate and has two excretory ducts. The gland mass relative to body mass was 0.143%. Both adenomer cells and their secretions were stained with Sudan IV, PAS and AB, and were positive for numerous lectins that indicated the presence of lipids and carbohydrates. Immunohistochemical techniques to detect PCNA confirmed cell proliferation in the basal stratum of the adenomer cells. The lipids and glycoconjugates secreted by the uropygial gland serve numerous functions including protection against microorganisms.

Morphology, morphometry, histochemistry and lectin histochemistry of the vagina of the plains viscacha (Lagostomus maximus).

The aim of the present work was to describe the morphology of the vagina in Lagostomus maximus and to characterize its epithelial cells using morphometric and histochemical techniques (variations of PAS, Alcian blue and lectin histochemistry). Thirty-five sexually mature adult females were captured in their natural environment during four periods of the year and their genital organs were dissected. The vaginal wall of the viscacha has three tunics: mucosa, muscularis and adventitia or serosa according to the region. The epithelium is stratified in both cranial and caudal regions, but its characteristics vary depending on the physiological state. In anestrous, nonpregnant females have a stratified epithelium of two to three cellular layers with columnar PAS-positive superficial mucous cells. During the follicular phase, the epithelium of the vagina is stratified squamous and cornified. Females at early, middle and term pregnancy have a columnar stratified epithelium with mucous cells. Glycoproteins in the mucous cells were detected using PAS, PA*S, KOH/PA*/BH/PAS; and Alcian blue, pH 0.5, pH 1, pH 2.5 and 0.006 M). Lectin histochemistry showed that UEA-I and RCA-1 lectins reacted strongly or moderately with epithelial cells in all stages analyzed. These results indicate the presence of L-fucose and ß-galactose. Binding with other lectins was variable.

Chorioallantoic and yolk sac placentation in the plains viscacha (Lagostomus maximus) - a caviomorph rodent with natural polyovulation.

OBJECTIVES: Reproduction in the plains viscacha is characterized by the polyovulation of hundreds of oocytes, the loss of implantation and the development of 1-3 offspring. Our goal was to determine whether placental development was affected by these specializations. STUDY DESIGN: Thirteen placentas from early pregnancy to near-term pregnancy were analyzed using histological, immunohistochemical and transmission electron microscopy. RESULTS: An inverted, villous yolk sac was present. Placentas were formed by the trophospongium, labyrinth and subplacenta. A lobulated structure with a hemomonochorial barrier was established early in pregnancy. Proliferating trophoblast that was clustered at the outer border and inside the labyrinth was responsible for placental growth. Trophoblast invasion resulted from the cellular trophoblast and syncytial streamers derived from the subplacenta. Different from other caviomorphs, numerous giant cells were observed. CONCLUSIONS: The principle processes of placentation in caviomorphs follow an extraordinarily stable pattern that is independent of specializations, such as polyovulation.

Development of compensatory hepatic hyperplasia in mice carrying the hepatocellular carcinoma ES12a.

In a previous paper we reported that the presence of the hepatocellular carcinoma SS1K in host mice resulted in an earlier appearance of the hepatocyte mitotic peak during liver regeneration after a partial hepatectomy as well as in an increase in the amplitude of that mitotic wave. In the present work we analyse the effect of another hepatocellular carcinoma, the ES12a (HCES12a). Adult male mice of the C3H/S strain standardised for circadian-periodicity analysis, were used. One group received a subcutaneous graft of the HCES12a tumor, while another group served as control. Fifteen days later, all animals were submitted to a partial (70%) hepatectomy at 10:00 h and beginning at 16:00 h lots of between 5 and 9 host and control animals each were sacrificed at 4 h intervals until 16:00 h on the third day thereafter. All mice were injected with 2 microg/g colchicine 4 hrs before killing, and samples of livers were processed for hematoxylin-eosin staining. We determined the hepatocyte mitotic index for each animal and the mean value +/- the standard error of the mean for each lot. The peak of mitotic activity in the tumor-bearing animals took place four hours earlier than in control mice but the average values of hepatocytic mitotic activity were similar in both groups

Effect of partial and sham hepatectomy on the growth of a hepatocellular carcinoma.

We examined the effect of partial hepatectomy on the proliferation of hepatoma ES12a grafted into C3H/S mice compared to tumor growth in sham-hepatectomized controls. The animals were sacrificed every 4 hrs during three days from the 6th to the 78th h following each type of surgery. Unoperated tumor-bearing mice were likewise killed as controls, but only during one complete circadian period. All animals received 2 microg of colchicine per g of body weight intraperitoneally 4 hrs before decapitation. Measurement of mitotic indices in hematoxylineosin-stained tumor samples revealed a decrease in proliferation and a modification of the diurnal mitotic-activity profile in the hepatectomized and sham-operated animals from the first day after surgery. These differences persisted by the third postoperative day only in the hepatectomized animals. Thus, although surgical stress may initially affect tumor growth, the latter results must be the effect of the influence of the hepatic regeneration.