Expressions and localizations of Bax/Bcl-2 proteins during metamorphosis of Pelophylax ridibundus.

Bcl-2 and Bax proteins are expressed in cells of the tails of Pelophylax ridibundus larvae. We investigated the levels of these proteins in tails undergoing apoptosis. Apoptotic cells were observed in the epidermis, muscle and notochord of tails of different lengths. The apoptotic cells in epidermis exhibited the typical features of apoptosis. Amorphous masses and irregularities in striated muscle tissue undergoing apoptosis and apoptotic remnants in the notochord also were observed. In general, Bax staining in the epidermis, subepidermal fibroblast layer, muscle and notochord cells increased, while Bcl-2 staining decreased as the tail regressed. Our results suggest that during tail regression due to metamorphosis, Bcl-2 and Bax proteins play key roles in the apoptosis of tail epidermis, subepidermal fibroblast layer, muscle and notochord cells.

Effects of a DNA demethylating agent--5-azacytidine--on testicular morphology during mouse embryo development.

DNA methylation is an epigenetical mechanism that plays crucial roles in cellular differentiation and tissue development in embryogenesis. The aim of the present study was to determine the effects of a demethylating agent, 5-azacytidine, on testicular development during embryonal life in mouse. Ten pregnant mice were administered 5-azacytidine (5-azaC) (i.p. 2 mg/kg of agent dissolved in 0.1 mg/ml PBS) during 8th (Group 1), 11th (Group 2), 14th (Group 3) and 18th (Group 4) days of pregnancy periods and male siblings of these animals were obtained (experimental groups) whereas the control group animals received no treatment and siblings of this group were also obtained. Testicular tissues from all groups were taken 20 days after birth and examined at the light and electron microscopical levels. All pregnancies were terminated in Group 1 animals, therefore no observations could be done in this group. While Group 2 and 3 siblings showed distinctive kongenital abnormalities such as; anancephaly, growth failure, cleft palate, extremity abnormalities, supernumerary ribs and whirled shaped-tails, no such abnormalities were observed in Group 4 when compared to the control group. Microscopical examination of testicular tissues in groups 2 and 3 demonstrated cellular disintegration of spermatocytes in seminiferous tubules. In addition, cytoplasmic vacuoles and thickening of the basement membrane were also evident in both groups 2 and 3. Apoptotic-like cells were seen especially in group 2 and rarely in group 3. There were no structural alterations in group 4 animals, except a decreased number of spermatocytes in seminiferous tubules when compared to the control group, possibly indicating the completion of embryogenesis in this group. In conclusion, it could be suggested that the demethylating agent 5-azacytidine may trigger an unknown gene reactivation during early embryogenesis possibly affecting the cell and tissue differentiation in developing mammalian embryos.

Comparison of the effects of vasectomy and experimental cryptorchidism in rats: I. Testicular histology.

The effects of cryptorchidism, one of the most important congenital malformations resulting with the defects in testicular structure thus infertility, is the best known subject in male reproduction. Those best known effects make the usage of cryptorchidism as a second control criteria when the effects of other male infertility reasons are attempted to be determined. Therefore the persistency or reversibility of the effects of vasectomy on testicular structure have been compared to the testicular features following experimental cryptorchidism and to the control group findings. To do this, rats were divided into 3 groups. While the control group animals were sham operated, the experimental group animals were undergone either vasectomy or experimental cryptorchidism procedures. Testicular histology of the control and experimental groups was determined using convenient staining methods at the light microscopical level. The comparison of the findings from the control and experimental groups showed that the testicular features of the vasectomized group were similar to those seen in the control group in contrast to the experimental cryptorchidism group which had irreversible testicular alterations. Results of the present study indicated the convenience of the usage of vasectomy in male contraception.

Blastocyst implantation in rats: a morphological approach.

Very complex cellular events take place at the morphological and molecular levels both in the maternal and embryonic sites during blastocyst implantation. Although the morphological alterations in the gestational stages of the implantation site are well-known, mechanisms of the interaction between blastocyst and endometrial epithelium (apposition and adhesion stages) and penetration of the blastocyst into the endometrium have not yet been fully described. Therefore the present study was designed to determine these events morphologically throughout the implantational stages. To do this the endometrial tissues containing implantation sites from pregnant rats were taken 5 and 8 days after fertilization. In addition, non-pregnant rat endometrial tissues were also obtained in order to use as control. Tissues were processed for light and electron microscopy. Semi-thin and ultra-thin sections were stained using appropriate staining methods, and were evaluated under light and electron microscope. In the present study, interaction between trophoblast and luminal epithelium, penetration of the blastocyst into the endometrium, differentiation of germinal layers in the blastocyst and tissue alterations such as decidualization in the maternal site have been demonstrated morphologically. In conclusion, while blastocyst was implanted into the endometrium, distinct morphological changes occurred both in maternal and embryonic sites. The following stages of implantation were the development of germinal layers in the embryo and morphological changes in the maternal site leading to the placentation.

Comparison of the effects of vasectomy and experimental cryptorchidism in rats: II. Epididymal histology.

Vasectomy is a male contraception method that its side effects and reversibility rate are still controversial. Effects of vasectomy on epididymal morphology and function, which plays a crucial role in sperm maturation and storage, have not yet fully described. Therefore the present study was planned to find out the effects of vasectomy on epididymal structure, and comparisons of these effects were also made with the effects of a persistent infertility model, experimental cryptorchidism. To do this, 15 male Swiss albino rats were divided into 3 groups. While 5 animals were sham-operated, the rest were undergone either vasectomy (5 rats) or experimental cryptorchidism (5 rats) procedures. Epididymal tissue samples were collected prepared for light microscopy. Tissue sections were stained using appropriate staining techniques and evaluated under the light microscope. While there were distinct alterations in the epididymal morphology following experimental cryptorchidism, vasectomized rat epididymal features seemed similar to those seen in the sham-operated group. In conclusion, it could be suggested that the vasectomy might be a convenient method for male contraception.