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M E Samar

Publications and source records attributed to M E Samar.

At least 37 records · Page 2Linked to original sources
PubMed1991

Structural variations produced in vitro by gonadotrophins and steroid hormones on the cell surfaces of the ovarian epithelium of the chick embryo.

The purpose of the present work was to analyze the structural variations produced "in vitro" by hormones on the cell surfaces of the ovarian epithelium of the chick embryo, in relation to the growth of the left ovary and atrophy of the right one. Explants of both ovaries from embryos at 7 to 19 days of development were separately cultured for 4 days in MEM with 10% of fetal bovine serum (control), and plus 17-beta-estradiol, testosterone propionate, progesterone, FSH, LH or hCG added individually to cultures (experimental). The cultures were processed for their structural, ultrastructural and cytochemical study. In control cultures, membrane differentiations and mucosubstances were similar in both ovaries and at all ages to those in ovo. 17-beta-estradiol produced a greater development of microvilli, junctional complexes and mucin in the epithelial cells and interdigitations in the germ cells of the left ovary, while in the right gonad there was cell regression. Testosterone and progesterone evoked in the left gonad a response similar to that obtained with the estrogen, whereas in the right ovary no changes were observed with respect to controls. FSH led to cellular regression in both ovaries. Finally, with LH or hCG the changes produced in the left ovary were similar to those induced by the estrogen, and in the right one an increase of membrane differentiations and of mucosubstances related to them was found in comparison to controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Human lingual organogenesis: histochemical and ultrastructural aspects].

The structural, ultrastructural and histochemical studies of tongues of human fetuses of 8 to 32 weeks development, were carried out to evaluate the possible chronologic coincidences in the differentiation process of the histologic components during organogenesis. From week 8 to 32, the epithelium increased its cellular layers, becoming flat, stratified, with parakeratinized areas, abundant desmosomes, tonofilaments and scarse intracellular granules. Chorionic fibers increased concomitantly, decreasing mucosubstances. Rudimentary papillae appeared on the dorsal surface of the tongue at 8 weeks, the fungiform ones being evident at 12 weeks. Glycoproteins in the basament layer became evident along with the papillary differentiation, reaching their definitive form at 20 weeks. Myoblasts were observed at 20 weeks. Glandular buds were noticed at the early age studied as were rich in glycogen inclusions and transversal striations were at 20 weeks the structural and ultrastructural differentiated acini, with PAS positive, metachromatic and alcianophilic secretions. The cytochemical changes observed are indicative of the cell differentiation process and tissues participating in the histogenesis present a similar rhythm of differentiation and growth.

Cell Differentiation↗
PubMed1990

In vitro effects of gonadotrophic and steroid hormones on the interstitial cells of the chick embryo ovaries.

The embryonic gonads produce and secrete the steroid hormones that induce secondary sex differentiation in different species. The production of estrogens, testosterone and progesterone by interstitial cells of the chick embryo ovary has been demonstrated in experiments in ovo and in vitro. Estrogens would be responsible at the 7th day of in ovo incubation, of the evolution of the functional left ovary. According to Gasc, only the cells of the germinative epithelium of the left ovary possess receptors for estrogens, thus originating the formation of a cortex in this functional gonad and not in the right one. On the other hand, extragonadal factors, such as gonadotrophins, would participate in gonadal differentiation. Involvement of the hypophysis in the morphological and functional differentiation of the ovary in the chick embryo, has been considered in several studies. Woods and Week established the functional hypophysealgonadal axis at 13 days of in ovo incubation. However, the effects of individual gonadotrophins on the interstitial cells of the chick embryo remain unclear. Avila et al. and Grassi Milano observed that when the female gonads were cultured without steroid or gonadotrophic hormones at the start of differentiation an hermaphrodite left ovary and a male right one were formed. Kyparissi and Vakolopoulu observed that the inoculation in ovo of FSH at the end of embryonic development led to an increment in the number and size of follicles in the left ovary. Pittini and Grassi Milano added FSH and LH to cultures of 15 days-old chick embryos testicles and ovaries and found that only male gonads developed similar to normal embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Acute pancreatitis induced by bile trypsin: structural and ultrastructural study].

The early lesions induced in the pancreas of dogs by the intraductal injection of bile-trypsin were studied. Histological, histochemical and electron microscopic techniques were used. The primary lesions analyzed thirty three minutes after the induction of pancreatitis consisted in cell alterations, blood stasis and oedema. At first, the affected acinar cells showed enlargement of the rough endoplasmic reticulum cisternae, later they were disrupted and then appeared vesicles with ribosomes adhering to the external surface. Mitochondria were swelled and showed cristae disrupted which finally appeared destroyed. The zymogen granules lost density, decreased in size and number and later disappeared, Ducts maintained the normal structure and their cells were still observed in areas where the tissue was greatly destroyed. the results obtained suggest that: 1) The experimental acute pancreatitis induced by bile-trypsin is characterized by primary and severe damage in the acinar cells, with secondary ischemia due to stasis and intravascular coagulation. 2) Cellular rests and probably endogenous enzymes invade the periacinar spaces, then would penetrate into the vascular system producing the generalization of lesions.

Acute Disease↗
PubMed1989

[Granulosa cells of the chick ovary: evolution studied during embryo development].

The ovary of the chick embryo starts differentiation from the 7th day of development. The left ovary grows progressively, whereas the right one undergoes involution. With the purpose of determining the degree of regression of the right ovary in relation to the diverse types of granular cells that form it, an ultrastructural study was made of embryonic ovaries of 7, 11, 15 and 19 days old. Three types of granular cells are described: A cells, similar to granulocytes, with phagocytic functions, B cells with semi-dense granules and functionally active C cells with granules of low electronic density. During development, A cells remain in the right ovary until 19 days. Nevertheless, there is not an increase in their amount in the involuting ovary. B cells diminish in the right ovary from 7 to 19 days; however, no modifications are found in the left ovary. These cells are considered precursors of the C cells due to the transition forms found in both cell types. C cells are seen in similar proportions in both ovaries at all the embryonic stages studied. It is important to note that there is a difference in the mechanism of hormonal induction at the level of these cells in the ovary that progresses as compared to the one that undergoes atrophy. Precursor B cells would be destroyed in the right ovary before undergoing a complete functional differentiation. These observations would indicate that both B and C cells are involved in the hormonal control of differentiation and estrogen secretion in both ovaries. With respect to type A cells, further studies are needed to establish their function.

Animals↗
PubMed1989

[Structural, ultrastructural and cytochemical study of interstitial cells of the chick ovary during embryo development].

It has been established that differentiation of the female gonad of the chicken is different in the right and left ovaries. Whereas the left ovary differentiates into the adult functional ovary, the right one suffers regressive changes and does not participate in the production of ova. Hence, we considered of importance to study the structural, ultrastructural and cytochemical characteristics of interstitial cells, which secrete estrogens in the left ovary and in the right one that undergoes atrophy, which has not been yet analyzed in this aspect. Chick embryos at 7, 11, 15 and 19 days of incubation were employed. The techniques used were H/E, Sudan IV, 3 -beta- hydroxysteroid dehydrogenase and transmission electron microscopy. At the light microscope these cells were clearly identified in the medullary cords, grouped in nests circumscribed by connective tissue, since 11 days of incubation. With H/E they exhibited a cytoplasm of foamy aspect and clear vacuoles of variable size. The amount of cell nests increased with the ages of the embryos. Besides, we found accumulation of sudanophilic granules and an enzymatic activity that increased during the course of development. At the ultrastructural level these cells contained an abundant smooth endoplasmic reticulum with tubules and vesicles, mitochondrias with tubular cristae and a considerable number of lipidic inclusions. The above mentioned elements confer to these cells and steroid-secreting activity. It is noteworthy that in the ovary that regresses interstitial cells do not disappear. In conclusion, we may point out that the right ovary would be rudimentary in ova formation, but would remain active with respect to hormonal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[In vitro development of the female gonads of chick embryos].

Having studied the functioning left ovary and the atrophic right ovary of the chicken during its in ovo embryogeny, we decided to study its development in vitro. For that purpose the explants of left and right ovaries of 7 at 19 days of in ovo development were cultured in Eagle medium, supplemented by bovine fetal serum and lated processed for structural and ultrastructural studies. At every ages the left ovary showed a cortex and a medulla while the right ovary had no cortex. Epithelial cells were observed in the cortex, encircling ovocytes having typical Balbiani's bodies formed by mitochondria, Golgi aparatus and centriole. Some nuclei were in the meiotic prophase. The right ovary and the medulla of the left ovary failed to show the lacunar aspect characteristic in the ovo study. Conversely, cell cords were found, formed by epithelial cells and ovocytes which being very close to each other, gave the cord a compact aspect. Among the cords, groups of interstitial cells could be seen, which were more frequent in the cultures of older ova and in both ovaries. The left and the right ovaries, therefore, developed according to the genetic pattern. Notwithstanding, the left ovary medulla and the right ovary would be modulated by extragonadal factors which would be inactive when the gonads are not in their natural environment.

Animals↗
PubMed1987

[Structural and histochemical characterization of a struma ovarii].

We have studied the thyroid tissue present in a cystic ovarian teratoma with the purpose of characterizing its structural and histochemical components. The methods of hematoxilyn and eosin, PAS, PAS/sialidase, Alcian blue at pH 2.5 and 1.0, were used, as well as, blocking reactions, Cason's thrichromic, and toluidine blue at pH 3.8. In the tissue we observed zones with follicles of normal appearance that varied considerably in size. The epithelium was constituted by cuboid cells surrounding a colloid substance of uniform aspect, that was strongly acidophilic, PAS positive and with variable reactivity with toluidine blue and weakly alcianophilic. With the thrichrome method, the different follicles stained in different tones. Parafollicular clear cells, bigger and less basophilic than follicular ones, with a nucleus having a lax chromatin, were identified. Cystic follicles were observed in whose cavities were conspicuous histyocytes surrounding rests of colloid substance, with metachromatic and PAS positive granules in their cytoplasm. Some groups of follicles were rudimentary, scarcely differentiated, and mostly without colloid. Others, with a greater degree of differentiation, showed diminutes follicles with intensely basophilic and PAS positive colloid. Beasides, follicular groups with excessive content of colloid appeared very distended and lined by a flat epithelium. According to the characteristics analyzed it may be concluded that: 1) it is a highly differentiated monoblastic teratoma, in which it appears non-encapsulated thyroid tissue; 2) the tumor resembles in different areas, either normal thyroid tissue, thyroid adenoma of the macrofollicular type, fetal or microfollicular and solid or embryonary adenoma, and follicles with the pattern of "thyroiditis".

Adult↗
PubMed1984

Cytochemical characterization of mucosubstances in the chick glandular stomach during embryonary and postnatal development.

The chick stomach is composed of two parts: glandular or proventriculus and muscular or gizzard which are morphological and functionally different. Since characterization of the mucosubstances in the adult stomach and its comparison with the embryonary stomach have not been made, we performed the study of the cytochemical characteristics of mucosubstances in the chick glandular stomach during the embryonic and post-natal periods, to obtain information on changes produced in these components during functional differentiation. In this work we established that during development, the epithelial cells of the superficial layer content predominantly glycoproteins and the glycosaminoglycans of the glands decrease when they begin to secrete other compounds, such as proteolytic enzymes necessary for digestion. This sequence of mucosubstances appearance is concordant with the increase of carbonic anhydrase, which reaches its highest specific activity from 15 to 20 days of incubation. In this period hydrochloric acid secretion increases and therefore, glycoprotein secretion becomes necessary to protect the mucous membranes.

Animals↗
PubMed1984

Acid phosphatase activity in the chick ovary during embryonic development.

Acid phosphatase activity was studied in the left and right ovaries of the chick during embryonic development. The cytochemical study indicated that local enzymatic activity is localized mainly in germ and somatic cells. From the results obtained in the study on the specific activity of this acid hydrolase, it can be inferred that the higher concentration of this enzyme in the right ovary would be determined by a decrease of total proteins in the total homogenate and in the cellular fractions of this organ. Besides, a decrease in the enzymatic activity of this ovary is not observed, but it occurs in the left ovary. This finding would indicate a lack of enzymatic segregation that could be related to the phenomenon of ovarian atrophy. Finally, the electrophoretic study indicated that it would apparently exist only one molecular form of the enzyme. Our results support the hypothesis that acid phosphatase would be involved in the atrophic processes of the right ovary during embryonary differentiation.

Acid Phosphatase↗
PubMed1983

Cytochemical study of the ovary cells in the chick embryo.

In the present work, cytochemical studies of mucosubstances, 3-beta-hydroxysteroid dehydrogenase and lipids in the different cellular types of chick embryo female gonads were performed, at 7, 11, 15, and 19 days of embryonal development. Oocytes from the cortical zone of the left ovary were characterized by the presence of a juxtanuclear cytoplasmic cap, which was basophilic, PAS positive, alcianophilic and acidophilic and was related to Balbiani's vitelline body. These staining characteristics either decreased or disappeared from 15 days in oocytes of the normal left ovary medulla as well as in oocytes of the atrophic right ovary.

3-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

[Morphohistochemical development of mesenchyme in human fetal labial glands].

The structural and histochemical patterns of the salivary mesenchyma were analysed in relation to the epithelium of the labial glands during the embryonic development to correlate the structural and histochemical characteristics in both tissues during the histogenesis. Samples of human fetal lips were analysed using H/E, PAS, Cason, Alcian blue, Toluidine blue and Methenamine/silver. The process of glandular histogenesis begun between 8 to 10 weeks. The mesenchyma surrounding the glandular buds had PAS positive granulations which were also alcianophilic, metachromatic and periodatoreactive. Periodatoreactive collagenous fibrillae, reticular cells and nervous fibers of considerable diameter were observed. Basement membranes were PAS positive, alcianophilic and discontinuous. At 12 weeks the mesenchyma differentiated as loose connective tissue which produced a delicate periglandular capsule with fibroblast and collagenous fibrillae. From 20 to 24 weeks the acini were structurally and histochemically differentiated as serous, mucous and mixed. It was postulated that the periglandular mesenchyma would play and important role in the morphogenetic process in relation to the histochemical identification of molecules which have a specific biological functions in the epithelium-mesenchyma interactions during organogenesis.

Histocytochemistry↗