Kotwica, J., Schams, D. and Meyer,H.H.D.: Secretion and metabolism of prostaglandin F₂α by endometrial tissue obtained at different days of the oestrous cycle in cattle. Acta physiol, pol., 1908, 39(5-6): 404-490. Two mature heifers were slaughtered on days 3, 6-7, 10-11, 16, 18-19 or on day 21 of the oesterus cycle. Endometrium was incubated in quadruplicates with medium-199 at 37 C and a water saturated gas phase of 95% O₂ + 5% CO₂. Half ml medium samples were taken after 6, 12 and 24 h of incubation for determination of PGF₂α and PGFM. PGF₂α was secreted by endometrium at each stage of the oestrous cycle. Maximal secretion was measured around oestrus (p<0.01) compared with days 6-16 of the cycle. Concentration of PGFM in medium had a similar trend. Highest ability of endometrium for PGF₂α metabolism (indicated by the ratio PGF₂α:PGFM) was on days 6-16 of the cycle. Data suggest that PGF₂α metabolism by the endometrium may depend on ovarian steroids and that this metabolism may also protect the corpus luteum from the luteolytic action of PGF₂α besides reduced production of this prostaglandin during the luteal phase.
Seasonal variation of testicular and epididymal parameters in the smallest deer, the southern pudu Pudu puda Molina, 1782 were related to the circannual fluctuation of plasma levels of its reproductive hormones. The diameter and the length of testes, the diameter of epididymis as well as the diameter and the heights of epithelium of seminiferous and epididymal tubules were measured, Morphological evaluation of spermatogenesis were performed on histological sections of testicular and epididymal tissues. Most of these gonadal parameters exhibit a seasonal variation which is in accordance with the reproductive pattern as well as the variation of reproductive hormones. Seasonal fluctuations of LH and testosterone indicate two seasonal activations of the reproductive system, one in the spring (antler mineralization), the other in the fall (rut), FSH exhibit one prolonged peak (summer to fall) whereas prolactin follows the expected, photoperiodically-dependant time course with peak levels around the summer solstice, The measurements of testicular parameters indicate a prolonged period of gonadal activity in southern pudu but the period of maximal reproductive stimulation is limited to the time around the rut.
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