Fenprostalene-induced luteal regression in the beef cow : histological and ultrastructural characterization.
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1987.
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| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy |
| Abstract: | Brahman-cross cows (day 11 or 12 of the estrous cycle) were used to study the effects of prostaglandin-induced luteolysis on the corpus luteum (CL). Four cows (0 h controls) were injected (sc) with saline while 16 cows were injected (sc) with a prostaglandin F[subscript 2α] analogue, fenprostalene (FEN). The CL-bearing ovary was excised at 0 (n=4), 4 (n=4), 8 (n=4), 12 (n=4) and 24 (n=4) h post-injection. Portions of the CL were stored at -20° C for analysis of progesterone (P4) concentration or fixed in either 10% formalin or 2% glutaraldehyde for evaluation by light or electron microscopy, respectively. P4 concentration in luteal tissue decreased (p<0.05) from 0 h (58.19 ± 16.85 μg/g) to 8 h (20.86 ± 2.44 μg/g) and CL weight decreased (p<0.1) from 0 hr (4.82 ± 0.3 μg/g) to 24 h (2.8 ± 0.3 μg/g) post-injection. Cell type shifted from predominantly Type I cells at 0 h to predominantly Types III and V 24 h later. Cell Type I decreased (p<0.05) from 0 h (57.20 ± 1.20% of luteal cells) to 12 h (34.15 ± 7.85%). Type V cells constituted the smallest percentage of luteal cells at 0 h (10.47 ± 2.36%) and increased (p<0.01; 33.12 ± 4.21%) by 24 h post-injection. Cell diameter decreased (p<0.01) from 0 h (30.00 ± 1.98μm) to 4 h (25.62 ± 1.61μm) and nuclear diameter decreased (p<0.01) by 8 h post-injection. The percentage of cell volume occupied by the nucleus at 0 h (4.68 ± 0.89%) was similar (p>0.01) across all time periods. The nucleus occupied a greater percentage (p<0.01) of small (<30.00μm; 7.58 ± 1.36%) than large cell volume ([greater than or equal to] 30.00 μm; 1.78 ± 0.24%). The number of lipid droplets in the plane of section increased (p<0.01) by 24 h post-injection, while lipid droplet diameter increased (p<0.05) by 4 h post-injection. Interval after FEN injection was inversely related to percentage of cell Type I (r=-0.78; p<0.05), CL P4 concentration (r=-0.58; p<0.05) and CL weight (r=-0.41; p>0.1). CL weight and P4 concentration were not related (p>0.1). CL P4 concentration was positively related to cell Type I (r=0.51; p<0.05) and inversely related to cell Type V (r=-0.52; p<0.05). The sequence of luteolytic changes after FEN administration began with a decrease in luteal cell diameter and an increase in diameter of lipid droplets and in CL P4 content. Subsequent decreases occurred in CL progesterone concentration (8 h) and in percentage of Type I cells (12 h). The decrease in CL weight at 24 h coincided with increases in the percentage of Type V cells and in the number of lipid droplets in luteal cells. We suggest that the decrease in CL P4 concentration during induced luteolysis coincides with increased accumulation of lipids and is succeeded by changes in morphological classification of luteal cells. These changes are consistent with the hypothesis that one of the mechanisms of prostaglandin-induced luteolysis may include inhibition of utilization of substrate for progesterone synthesis. |
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| Item Description: | Typescript (photocopy). Vita. |
| Physical Description: | xiv, 119 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 71-88). |