Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 3

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  pecherzyki przedjamiste
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
No offspring have yet been obtained in horses either from oocytes collected from preantral follicles or other ones maturing in vitro. The available literature does not provide any detailed description of the ovary with respect to distribution and morphology of the ovarian follicles. The purpose of the study was to define the location and histomorphology of preantral follicles in the mare ovary in order to find if it is then possible to isolate and cultivate it. The investigations were carried out on some histological samples of longitudinal and transversal sections of mare ovaries which were collected from a 6-year-old anoestrus mare at 10 minutes after slaughter. From among 821 preantral follicles, wihich were located and evaluated, 567 came from transversal sections and 256 from the longitudinal ones. The preantral follicles were found in all parts of the ovary stroma. In a single histological preparation from a transversal section an average number of 70,5 preantral follicles were found and in a longitudinal one there were 84.7 preantral follicles the size of 35.2 and 45 µm, respectively. The follicles mostly occured singly (54.7%) or in groups of 2 to 7 (45.3%). Among all the preantral follicles 31.2% were defined as artretic, 30.6% were found in the group of the primordial ones and 63.6% in the secondary ones. The percentage of artretic follicles increased with the stage of follicular development. Isolation of the follicles from ovary, their culture and in vitro maturation still remains a problem. The present study indicates that samples collected from any part of the ovarian stroma can be used for this purpose.
The aim of the study is to present current knowledge on the mechanisms regulating puberty in mares and the possibility of shortening the intergenerational period in horses through modern animal reproduction biotechnology. The study discusses fetal sex recognition in horses by means of ultrasound, pre- and postnatal development of mare gonads, oogenesis and folliculogenesis, as well as the process of selection and elimination of oocytes. It also describes the role of gonadotropins, ovarian hormonal activity and morphological changes occurring during sexual maturation. It has been shown that about 37% of mares attain sexual maturity in the first year of life. It has also been documented that one-year and two-year-old fillies produce normal embryos that can be used for transplantation and give offspring. It has also been proved that embryos can be produced in vitro from oocytes of juvenile mares. There is hope that acquiring preantral follicles from the ovary and their in vitro culture until the oocyte reaches full maturity for fertilization will permit us to obtain embryos and offspring from mares, including those sexually immature. These methods, combined with in vitro fertilization and embryo transfer techniques, have already made it possible to obtain normal embryos and even live-born offspring in other mammals.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.