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C. H. CHEN, D. C. KLEIN and J. C. ROBINSON

The present report is the first in a projected series of investigations on biogenic amine-synthesizing and -degrading enzymes in trophoblast. The work is being undertaken to gain information relating to two questions. First, do the placental enzymes which degrade biogenic amines and related compounds provide an important biochemical barrier which protects the fetus against undesirable stimulation by physiological and pharmacological compounds in the maternal circulation? Secondly, do critical changes in biogenic amine metabolism in the placenta precede or accompany parturition, and might they be involved in the actual mechanism underlying the initiation of parturition?

Catechol-O-methyltransferase (COMT, E.C.2.1.1.6) is an enzyme which inactivates certain catecholamines and O-methylates 2-hydroxyoestradiol-17 β (Ball, Knuppen, Haupt & Breuer, 1971); it has been purified 66-fold from human placenta (Gugler, Knuppen & Breuer, 1970).

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C. H. Chen, D. C. Klein and J. C. Robinson

Summary.

The activity of monoamine oxidase (MAO), an enzyme which metabolizes catecholamines and indoleamines, was determined in rat placenta at various stages of gestation, in human term placenta, and in choriocarcinoma grown in culture. From Day 15 to Day 20 of gestation the specific activity (units/mg protein) of MAO in rat placenta increased at least 3-fold; from Day 20 to the time of parturition, it decreased about 50 %. The specific activity of MAO in human placenta at term was about 8 times higher than that of rat placenta at term. No MAO activity was found in choriocarcinoma grown in culture.

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R. J. REITER, D. C. KLEIN and R. J. DONOFRIO

Removal of the eyes (Reiter, 1968) or of the olfactory bulbs (Orbach & Kling, 1966) slightly delays gonadal maturation in rats. The gonadal inhibitory effect of blinding is prevented if animals are pinealectomized (Reiter, 1968). It was found recently that if weanling male rats have both their eyes and olfactory bulbs removed, the testes are less than half their normal size at 70 days of age; this entire effect is reversed if the animals also have their pineal gland removed. This indicates that another external factor, in addition to the photo-period, may influence directly or indirectly the antigonadotrophic activity of the pineal gland. The experiment was repeated and the following data illustrate some interrelationships between olfaction, photo-period, the pineal gland and reproduction. Sixty-four 21- to 23-day-old
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L A Silva, C Klein, A D Ealy and D C Sharp

This work examined how the conceptus modulates endometrial tissue remodeling and vascular development prior to implantation in mares. A macroscopic uterine examination was completed at day 21 of pregnancy. In situ morphology revealed that the endometrium involved in encroachment is restricted to the dorsal endometrium immediately overlying the yolk sac. The amount of stromal area occupied by blood vessels and the number of endometrial glands were increased during early pregnancy. Endometrial histomorphometry as well as the endometrial mRNA abundance and immunolocalization of VEGF, VEGFR1, VEGFR2, and Ki-67 was completed at days 14 and 21 of pregnancy, at day 10 of the estrous cycle, and during estrus. No obvious differences in VEGF and VEGFR1 protein localization were detected between pregnant and cycling mares but differential staining pattern for VEGFR2 and Ki-67 was observed. VEGFR2 localized to luminal and glandular epithelium of pregnant mares, while luminal epithelium was negative in cycling mares. Ki-67 staining was weak during the luteal phase but exhibited prominent luminal epithelium staining during estrus. In pregnant mares, all endometrial layers were Ki-67 positive. Quantitative RT-PCR revealed a greater abundance of VEGF mRNA during pregnancy. VEGFR2 transcript abundance was greatest in pregnant mares on day 21. This study supports the concept that the conceptus plays an active role in directing vasculogenesis within the uterus and thereby establishing hemotrophic nutrition that supports pregnancy after implantation.

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D Rath, S Barcikowski, S de Graaf, W Garrels, R Grossfeld, S Klein, W Knabe, C Knorr, W Kues, H Meyer, J Michl, G Moench-Tegeder, C Rehbock, U Taylor and S Washausen

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D Rath, S Barcikowski, S de Graaf, W Garrels, R Grossfeld, S Klein, W Knabe, C Knorr, W Kues, H Meyer, J Michl, G Moench-Tegeder, C Rehbock, U Taylor and S Washausen

Pre-selection of spermatozoa based on the relative DNA difference between X- and Y-chromosome bearing populations by flow cytometry is an established method that has been introduced into commercial cattle production. Although several important improvements have increased the sort efficiency, the fertilising ability of sexed spermatozoa based on offspring per insemination is still behind farmers' expectations. The main stress factors, especially on mitochondria, that reduce the lifespan of spermatozoa are described, and new technical as well as biological solutions to maintain the natural sperm integrity and to increase the sorting efficiency are discussed. Among these methods are the identification of Y-chromosome bearing spermatozoa by bi-functionalised gold nanoparticles and triplex hybridisation in vivo as well as new laser-controlled deflection system that replaces the deflection of spermatozoa in the electrostatic field. Additionally, as well as a new nonsurgical transfer system of spermatozoa into the oviduct of cows has been developed and allows a significant reduction of spermatozoa per transfer. Altogether, the improvements made in the recent years will allow a broader use of sex-sorted spermatozoa even in those species that require more cells than cows and sheep.