Megasporogenesis and female gametophyte development were investigated in ovules of the everbearing strawberry Fragaria x ananassa Duch. cv. Selva. Observations of thin sections revealed that ovule development starts from the formation of a nucellus and coincides in time with the beginning of receptacle overgrowth. The most characteristic feature during nucellus differentiation is the formation of a multicellular archesporium, beginning from at least two cells. Analysis of female gametophyte development indicated that in addition to the meiotic mode, female gametophytes develop by an apomeiotic mode of Antennaria type. Asynchronous development of female gametophytes of different origin occurs. The mature, eight-nucleate, seven-celled female gametophyte of meiotic origin is cylindrical and slightly curved. It occupies the central part of the nucellus. The egg apparatus, consisting of an egg cell and two synergids, is formed in the micropylar part of the female gametophyte; the opposite chalazal pole is occupied by antipodal cells. Besides the ovule in which only one seven-celled female gametophyte finally develops, ovules with a different number of cells were observed to initiate female gametophyte development. Some ovules contain a nucellus with a tetrad of linearly arranged megaspores surrounded by enlarged cells, each of which has the potential to develop into an apomictic female gametophyte. After degeneration of some post-meiotic cells or developmentally advanced female gametophytes, some of the chalazal cells initiated female gametophyte development.

The aim of the study was to evaluate the effect of repeated low doses of GnRH agonist buserelin once a day for 5 days on follicle development and ovulation in anovulatory dairy cows with follicles growth only to emergence. The study was conducted on 71 anovulatory Polish Holstein Friesian cows. Anovulation with growth of follicles to emergence was defined as small ovaries with follicles of ≤ 5 mm in diameter and without corpus luteum on two examinations in a 7-10 day interval between 50-60 days after parturition. Cows were allocated to one of two group. Cows from group 1 (n = 58) received 0.4 μg of buserelin (Receptal, MSD, Poland) i.m. once a day for 5 days. Control cows from group 2 (n = 13) received saline. Ovarian structures were monitored weekly after the end of treatment by ultrasound for 4 weeks. The diameter of ovarian follicles on the ovaries was measured and recorded. Occurrence of ovulation was determined by the presence of corpus luteum. Overall, ovulation occurred in 46.6% (27/58) of cows treated with repeated doses of GnRH, while no corpus luteum was observed in the control group during the study period. There were significantly (p<0.05) more follicles 6-9 mm in diameter and 10-20 mm in diameter in cows treated with GnRH than in control cows. In conclusion, repeated low doses of GnRH analogue buserelin once a day for 5 days stimulate the development of ovarian follicles in anovulatory dairy cows with small ovarian follicles and led to ovulation in 46.6% of cows during 4 weeks after the end of the treatment.

The aim of this study was to determine how puerperal metritis influences the resumption of estrous cycle in dairy cows. The ovaries of 72 multiparous Holstein cows (38 healthy and 34 metritic – after treatment) were ultrasonographically scanned until the first ovulation post- partum and 7 days after to confirm the ovulation. All 72 cows were divided in to 4 groups: HSO (healthy with single ovulation) (n=29), MSO (metritic with single ovulation) (n=21), HDO (healthy with double ovulation) (n=9), and MDO (metritic with double ovulation) (n=13). The proportion of cows that had DO in the first ovulation postpartum was similar between M and H groups, 38.2% and 23.6%, respectively (p>0.05). There was a difference between HDO and MDO groups comparing the first dominant follicle ovulation postpartum (11.4±2.7 and 20±1 days, respectively p<0.05) and the diameter of the ovulatory follicles (15.3±1.9 mm and 17.3±1.7 mm, respectively p<0.05). The percentage of cows that had double follicle domi- nance in the first follicular wave after first ovulation was higher in the M groups (33.3% (MSO) vs. 6.9% (HSO) (p<0.05) and (69.2% (MDO) vs. 22.2% (HDO) (p<0.05)). The MSO group dominant follicle diameter was bigger for cows which had one dominant follicle (p<0.05). It might be concluded that dairy cows after puerperal metritis need more time until the first ovu- lation. Also, metritic cows have a higher risk for double dominance in the first follicular wave, after the first ovulation.

This study investigated the details of the morphological and anatomical structure of the generative organs of the Subantarctic flowering plant, belonging to the family Caryophyllaceae - Colobanthus apetalus (Labill.) Druce. The research material was collected in hostile natural conditions in Subantarctic regions, and also was grown in the incubators and the greenhouse of the University of Warmia and Mazury in Olsztyn (Poland). C. apetalus forms tufts with soft and grassy leaves and small greenish flowers that are more obvious than in other Colobanthus species. C. apetalus forms open (chasmogamic) flowers in greenhouse cultivation. The flowers most often form five stamens with two microsporangia. Over a dozen pollen grains are formed in each microsporangium. Studies of the plant material originated from natural conditions conducted by means of a light microscope, have shown that the ovules of the analyzed representative of the genus Colobanthus are anatropous, crassinucellar, and the monosporic embryo sac develops according to the Polygonum type (the most common type in angiosperms). C. apetalus plants underwent a full development cycle in greenhouse cultivation and produced fertile, perispermic seeds. During the C. apetalus growth in conditions at increased air humidity, the vivipary was also observed.

This study was carried out to determine the time-dependent changes in the ultrasonographic image of the ovary with computer-assisted analysis programs at certain intervals after ovulation and to determine whether computer-assisted analysis programs and ovulation programs can be managed in cases where the ovulation time is unknown. The study included 40 purebred Arab mares. The study was subdivided into 4 different time periods of 6 (Group 1), 12 (Group 2), 18 (Group 3) and 24 (Group 4) hours following ovulation. In addition, after ovulation and ultrasonographic examination, natural insemination was performed at 6, 12, 18 and 24 hours, and pregnancy examination and follow-up were performed at 15-30-45 days. In the echotexture analysis, mean grayness value (MGV) and contrast (CON) measurements were at different levels according to the time groups (p<0.001). Homogeneity (HOM) measurements were at different levels according to the time groups (p<0.001). A very strong, significant negative correlation was determined between MGV and pregnancy rates (r=-0.91, p=0.01, p<0.05). No significant relationship was observed between HOM values and pregnancy rates (r=0.19, p=0.23, p>0.05). A very strong, significant negative correlation was determined between CON and pregnancy rates (r=-0.92, p=0.01, p<0.05). It was concluded that the use of ultrasonographic echotexture in mares after ovulation provided very important information. In cases where the time of ovulation was not known, by looking at the values of echotexture parameters, it was seen that the highest pregnancy rates were at the 6th hour and the lowest pregnancy rates were at the 24th hour. As the echotexture parameters MGV and CON increased, it was determined that pregnancy rates decreased, but there was no relationship between them and the HOM value.